RECONSTRUCTING THE FLIGHT

©Jay Hopkins – All rights reserved

Originally published in Flying April, 2008

 

There are a number of reasons why around 700 people die each year in aircraft operating under Part 91 and Part 135, while Part 121 operations sometimes go an entire year without any fatalities. Airlines have stricter regulations, and operations manuals spell out every nuance of how a flight and the entire airline will be run. When they do have an accident, the flight data recorder and cockpit voice recorder usually allow the NTSB to get a pretty good idea what led to that accident, allowing everyone to learn from that accident and avoid the same thing in the future.

Part 121 operations have one other advantage that a lot of general aviation pilots may not be aware of. All major carriers now have a Flight Operations Quality Assurance program (FOQA) that analyzes the data from the flight data recorders to look for operational trends that might lead to an accident in the future if not corrected. FOQA programs got started in Europe in the mid 1970s when airlines realized there was a wealth of information on flight data recorders that could be utilized to enhance the safety and effectiveness of airline flight operations.

The FOQA programs are not used to “spy” on flight crews. Instead, deidentified data from all flights is analyzed by computers to search for trends that could ultimately result in an accident. In one example cited by Christopher Jesse of the Institute of Industrial Research at the University of Portsmouth, England, an airline FOQA program discovered that its aircraft were often slowing to V2 after takeoff. The flight data showed that pilots were pitching the aircraft too high in the initial climb, resulting in a reduction in airspeed. An engine failure at that point could have resulted in a serious incident or even an accident. The airline could use this information to adjust its training program to address the problem.

The FOQA programs rely on heavy, expensive flight data recorders, putting this type of data analysis beyond the financial means of charter or corporate operators, flight schools, or individual pilots. To overcome this problem, UHL Research Associates (www.uhlflight.com) has spent the last 12 years developing a Flight Reconstruction System (FRS) that weighs less than two pounds and is available for under $3000.

The UHL-FRS has a one pound flight recorder that is a refinement of a system developed by David Ellis to eliminate the need for a barograph on competitive glider flights. It utilizes an internal GPS, a solid state gyroscope and a highly accurate 10 g three axis accelerometer to take a digital snap shot of what the aircraft is doing every tenth of a second. It also includes a less accurate 50 g three axis accelerometer that can record the forces experienced during a crash.

The data is stored in a hardened memory unit that can store up to 8,000 hours of flight data and is typically placed in the tail to enhance survivability in case of an accident. The memory unit is connected by a data cable to the flight recorder, which also has inputs for dynamic and static pressure, gear and flap position, and other aircraft system status information that can be recorded if desired. The flight recorder also has a flash card interface that allows the data from the memory to be extracted for analysis.

The reason the hardware is so simple and inexpensive is that most of the work is done after the data is removed from the aircraft by software developed by Urban Linch, the founder of UHL Research Associates. The software takes about 20 seconds to analyze a one hour flight and produce a three dimensional wire frame reconstruction of that flight with both an external view and an out of the cockpit view. Over 18 other parameters are also available for each data point, including heading, airspeed, altitude, bank angle, and pitch, yaw and roll attitude. The reconstructed flight can be viewed real time, or any specific point of the flight can be analyzed in detail. A blue line shows the path of the aircraft through the air, while a green line shows the path across the ground. Yellow lines are used to indicate desired flight tracks and stabilized approach windows, while white lines show runways.

Linch has been testing and refining the Flight Reconstruction System over the past decade. For example, the US Air Force is very interested and spent 21 hours testing the system on the F-15, F-16 and T-38. They found that the output was 95% accurate when compared with the actual aircraft parameters, and said this was “good enough” for their application. Even better, the software can combine the output from 32 separate aircraft to help analyze air combat maneuvering or aerobatic team performance.

The applications for this system are almost unlimited. While every operator could benefit from the analysis of operating parameters and variances, there are specific benefits for some applications:

Aircraft Manufacturers

Quartz Mountain Aerospace (www.qmaero.com – formerly Luscombe Aircraft) will be equipping every airplane they sell with the Flight Reconstruction System. They found that both the insurance companies and the leasing company they will be selling to are very interested in the system, as it could protect them by showing whether an accident was caused by an aircraft malfunction or pilot error. Quest Aircraft Company (www.questaircraft.com) will be putting the FRS into all the Kodiak single engine turboprops they deliver.

Flight Schools

I am very familiar with the advantage of being able to reconstruct an instructional flight. At SimuFlite we would generate printouts of various maneuvers and approaches to show the pilots exactly how they did. We could also tape the cockpit view during various maneuvers. It is often hard to describe exactly how the pilot was over controlling on an approach. With the FRS, the student can see exactly what he was doing in real time. As they say, a picture is worth a thousand words, and the pilots often couldn’t wait to see the tape after a session to help them understand and learn from the mistakes they had made. I could see how this could even become a marketing factor for schools that equip their aircraft with the FRS, as it would greatly enhance the effectiveness of the debriefing session after an instructional flight, allowing students to progress more rapidly.

The FRS can also help flight schools monitor student solo flights and keep track of how rental pilots are operating their airplanes. One flight school in Malaysia that equipped an airplane with the FRS system was surprised to learn that a student pilot on a solo cross country flight did not follow the intended flight plan but instead wandered off to different areas where he was not supposed to go. This kind of blatant disregard for the rules could easily lead to an accident in the future.

Aerobatic Teams and Military Flight Operations

Since the UHL software can combine the recordings from up to 32 aircraft into one presentation, it would be very useful for an aerobatic team to analyze their performance. The military can use it for training in aerial combat maneuvering, allowing each pilot to see exactly how they flew and the effectiveness of various maneuvers.

Post Accident Analysis

This is where the FRS would really pay for itself. One of the most frustrating issues in general aviation is that many time we have no idea why an airplane crashed. This often leads to complicated litigation with the pilot’s estate blaming the manufacturer and the manufacturer blaming the pilot. An FRS would show investigators exactly what happened, which could reduce expensive litigation and hopefully result in reduced insurance rates for everyone.

Mission Aviation Fellowship (MAF) has already experienced the power of this system. They tested eight demonstration recorders in some of the most difficult flying in the world to verify the accuracy of the units. During the demonstration period, an FRS equipped airplane landed short of the runway in Indonesia at a remote landing strip that requires strict adherence to the specified approach procedure.

Ordinarily it would have been assumed that the pilot had somehow lost his focus and caused the accident. By analyzing the FRS recording for this and other landings at this location, MAF determined that the pilot had done everything right, and that there were dangerous wind gusts at certain times of the day that necessitated going to more conservative wind restrictions at that strip. Dave Rask, the Manager of Aviation Safety for MAF, said they are going to install the FRS in additional aircraft and eventually hope to equip their entire fleet worldwide with this system.

Summary

With any new system that monitors aircraft operation, there is bound to be resistance from pilots and instructors who don’t like the idea of anyone looking over their shoulders at everything they do. Once pilots understand that the data is typically used for deidentified trend and variance analysis to improve flight operations, and that it can exonerate a pilot after an incident or accident that was not their fault, I believe the inherent value in this system will become evident. Over time, the information derived from many flights and accidents could allow us all to learn how to avoid those kinds of accidents in the future, ultimately saving lives by reducing the number of people who die each year in general aviation accidents.

PERSONAL CHECKLIST

©Jay Hopkins – All rights reserved

Originally published in Flying February, 1993

Maintaining good “Situational Awareness” is of the utmost importance for a pilot.  Running out of fuel, encountering “inadvertent” instrument conditions, and colliding with terrain or another aircraft often are the result of at least a partial loss of situational awareness.  And of course landing at the wrong airport by definition indicates a complete lack of situational awareness.  The problem is that this is a fairly nebulous term, making it hard to nail down the exact extent of loss of situational awareness in any accident.  However, there are some specific steps we can take to enhance our capability to maintain good situational awareness and to increase the odds that we will quickly realize when we have lost it.

We can define situational awareness as the accurate perception of all factors and conditions affecting the aircraft and crew during a specific period of time.  This includes being aware of what has occurred in the past in relation to what is going on now, and how all this may affect the future of the flight.  In a previous article we determined that there are up to nine different areas that a pilot has to keep track of during a flight: attitude of the aircraft, location of other aircraft, time, weather, position, systems status, airport/navaid status, maintenance status, and possibly crew and/or passenger status.  If we are to maintain good awareness of all these parameters it is critical that all our sensors are working well.  In the same way that we preflight the aircraft and check the weather before each flight, we should also review our own condition to see if we are ready to take on the responsibility of pilot-in-command.  A good way to accomplish this is to use the memory aid “I’M SAFE”:

Illness – Are you sick or experiencing any symptoms which might distract from paying full attention to your flying duties?  Have you fully recovered from a previous illness?  Somehow pilots seem to only have the flu for one day when everyone else is laid up for at least three days.

Medication – Did you take any medications, and if so, is there any possibility they could affect your flying?

Stress – We all are under stress of some sort in our personal lives, and various types of stress affect people differently.  It is important to assess your stress level as you prepare for each flight.  Has it reached the level where it could distract you or affect your operation of the aircraft?  In particular, has something happened that is especially upsetting to you?

Alcohol – Not only are you legal to fly (eight hours bottle to throttle and below .04% blood alcohol level), but are you free of any influence from alcohol or its after affects?  It has recently been shown that the effects of a hangover can be just as debilitating as the effect of alcohol on our senses and reasoning.

Fatigue – Are you adequately rested, considering the duration of the planned flight and the difficulties you are likely to encounter?

Eating – Have you had enough nourishment, and are you bringing sufficient food along with you?  Many people have a hard time concentrating when they are hungry, so after a long flight it’s a good idea to have a snack before a difficult approach.

Finally, look at the big picture.  It’s very possible to have several of these factors active at the same time.  For example, you may have been sick, and because of this you haven’t been eating or sleeping well, and you have been taking over the counter medications for your symptoms.  There are no easy answers as to whether it is safe to fly, that is up to you as the PIC.  The important thing is to make sure you are aware of all the factors that may be affecting you, and to weigh the possible effect of these factors against the demands of the flight you are about to undertake.  Our standards need to be much higher for a night flight in IMC compared to a local day VFR hop.

It might seem silly to use a memory device to check if you are sick, or if you have had a drink, but I know from experience that it is very easy to overlook any of these items in the midst of preparing for a flight.  At one point I was on call to fill in for a courier if they encountered any problems.  One evening they called just as I was finishing dinner.  I quickly drove to the airport, loaded the aircraft, and took off for Phoenix.  I gradually became aware that I just was not as sharp as I normally was.  Then it dawned on me, just like in the V8 commercials, I had a beer with dinner!  I had not been “drinking” as such, it was just a beverage to go with pizza, so when the call came it never occurred to me that I should not take the flight.  If I had quickly run through “I’M SAFE” I would have BEEN safe!  I also would have been able to spend the evening with my children, instead of flying to Phoenix.

Once we are in flight, becoming aware of a serious loss of situational awareness is difficult because by definition, if we have lost situational awareness, we don’t know what is going on and therefore don’t know we have lost it!   There are twelve warning signs of a loss of awareness which we should tuck away in our brains, ready to alert us whenever necessary:

FIXATION – You realize you have stopped scanning and are just staring at one instrument.

AMBIGUITY – You have information from two independent sources which disagrees and can’t be resolved.

COMPLACENCY – The better you think you are doing, the greater should be your cause for concern.

EUPHORIA – If you are ecstatic about a new baby, a new airplane, or some achievement in your life, watch out!

CONFUSION – Often when we have lost situational awareness we will have a gut feeling that something isn’t right.  We call this feeling a “pinch.”

DISTRACTION – You become aware that your attention is being drawn to an item that is not really all that important.

UNDERLOAD or OVERLOAD – If the flight is so easy it’s boring, you may not be paying attention to important information.  If you are so busy you can’t think, it is very likely you are overlooking something.

POOR COMMUNICATIONS – Difficulty communicating with ATC or a crew member may indicate someone doesn’t know what is really going on.

FAILURE TO MEET TARGETS – If you are reaching checkpoints significantly early or late, or if your speed or fuel consumption is very different from what you planned, you need to find out why.

IMPROPER PROCEDURES – If you catch yourself doing something wrong, you need to look around for other errors you may have committed.

UNRESOLVED DISCREPANCIES – Things just don’t add up.

NO ONE FLYING THE AIRCRAFT – This is a prime indication that things have gotten out of hand.

Typically our first clue to a loss of situational awareness will be an uneasy feeling we can’t really put our finger on, based on one or more of the symptoms listed above.  Often it is manifested as a vague sense of confusion, a gut feeling that something isn’t right, which we refer to as a “pinch.”  Unfortunately we often ignore or dismiss these early warning signs until things get so bad we can’t miss the problem.  The key to quickly identifying and responding to a loss of situational awareness is to focus on the uneasy feeling and to verbalize to ourselves and any crew members that “Something isn’t right!”  The act of putting your feelings into words will help you to focus your thoughts on reviewing the situation and finding out what is going on.

One of the best examples of this happened to me at the end of a long training flight in a Lear 35.  I was the instructor, copilot, and safety pilot for three pilots who had just received their Learjet type ratings in a Phase II simulator.  The purpose of the flight was to give each person a chance to fly a typical Learjet flight profile, including a number of approaches.  My job was to keep us alive.  We departed Dallas Love Field on runway 13R and had just enough time to climb to altitude before it was time to descend for the approach into Amarillo.  We did a missed approach and several more practice approaches before landing to stretch our legs and switch seats.  Of course I didn’t get to switch seats.  I was stuck in the right seat for the duration of the flight.

We flew a similar profile to San Angelo, and after switching seats again were on our way back to Dallas with the last pilot getting his chance in the left seat.  As we got close I monitored the ATIS and was sure I had heard that runways 13 left and right were still the active.  Of course, the reciprocal is 31, so the chance of a mistake was not insignificant for a very tired instructor/copilot who had spent four and a half hours in the right seat, almost none of it straight and level.  It was one of those marginal VFR days due to haze, and as we were being vectored I began to get that funny feeling in the pit of my stomach that something wasn’t right – the “pinch”.  It was taking too long to get on final, and the headings we were getting didn’t make sense.  But because of my fatigue I just sat there “fat, dumb and happy” until the controller suddenly told us, “Turn right, intercept the localizer, cleared for the ILS 31 right approach.”  With my situational awareness snapped into focus, I knew we were totally unprepared for the 31R ILS, so I finally did something smart and declared a missed approach to ensure we didn’t conflict with any traffic for 31 left.  If I had verbalized my uneasy feelings earlier on the approach, we could have reviewed our understanding of the situation and probably would have realized our mistake.

OPERATIONAL DISTRACTIONS

©Jay Hopkins – All rights reserved

Originally published in Flying September, 1993

The commuter airline crew was very experienced in the Beech 99, with over 7,000 hours (captain) and 3,000 hours (copilot) in that type aircraft.  Yet as they flew the approach into Spokane they descended below the MDA and hit a hill 4.5 miles from the end of the runway.  The NTSB determined that this was probably due to the DME being held on the Spokane VORTAC rather than indicating the distance to the runway from the localizer DME transmitter.  The NTSB further surmised that the crew had been distracted by the landing gear warning horn and light which may have come on just as they were about to reposition the DME selector switch.

Accident investigators are hampered in their analysis of small plane accidents by the lack of a cockpit voice recorder or a flight data recorder.  If we were able to hear what was really going on in the cockpit just prior to an accident, we would probably find that in many cases some sort of distraction was a factor.  The problem is that although it may seem like we can be doing several things at once, in reality we can only concentrate on one item at a time.  Anything that catches our attention, even casual conversation, can divert our attention from the task at hand.

Another problem is that as we initiate a procedure we first do it mentally.  If something distracts us in the moment between thinking about doing something and actually doing it, we may have mentally checked that item off as accomplished, even though it wasn’t.  In the case of the Beech 99, one of the pilots could have stated that it was time to change over the DME and started to do so when the gear warning horn and light activated.  The normal response at that point would have been to cancel the warning horn and if appropriate, extend the gear.  By the time that was accomplished, they may have gone on to other tasks and forgotten that the DME selector switch had not been taken out of the hold position.

Anything related to the flight operation which diverts our attention from the task at hand is called an operational distraction.  Even a normal, required function can be deadly if it distracts us from critical safety of flight awareness.  In a NASA study of airline flight operations, the leading operational distraction was found to be reading checklists.  Obviously the checklist is there to help ensure we complete all required items, but some thought must go into how it is used.  The bottom line is that the checklist can’t fly the airplane, but it can distract us from doing so, or from monitoring another pilot during critical flight operations.

Since it is usually up to us to decide when we will accomplish checklist items, sit down with your checklist and see what you can do to move as many items as possible to non-critical periods of the flight.  For example, the Taxi Checklist should contain only items which must to be checked while under way.  These include brakes, turning indications on navigation instruments and the thrust reversers on jet aircraft.  Everything else should be moved to either the Before Taxi or Before Takeoff Checklists so they can be checked when the aircraft is stationary.

The same philosophy holds on approach.  Everything possible should be completed before the final approach point on an instrument approach, or before entering the pattern on a visual approach.  It just doesn’t make sense to be involved in the most critical phase of the flight with the pilot or part of a crew reading a book!  This is especially true in bad weather.  In one example of the dangers of distraction, a corporate S-76A collided with trees during a night landing at a company helipad.  The weather was reported as partial obscuration, 200 feet broken, visibility 1 mile with fog and rain.  The wind was calm.

The crew flew a VOR approach monitored by radar.  The copilot spotted the pad and called it out to the pilot, who started a steep descent.  If ever there was a time for the copilot to be monitoring the approach this was it.  But he diverted his attention inside the cockpit to complete the Landing Checklist.  Suddenly he sensed that the helicopter had a nose high attitude and looked out.  The aircraft appeared to be moving backward and down so he yelled, “Where are we going?”.  The captain added power but it was too late and the aircraft entered the trees, ruining the rotor blades and causing a hard landing that seriously injured one of the pilots.

In another case involving a King Air, an ATP rated pilot was checking out another commercial rated pilot in the aircraft.  As they were making a takeoff from a touch and go, the commercial pilot became distracted looking for the flap control and allowed the aircraft to descend into the water.  Why didn’t the other pilot in the right seat realize what was happening and take corrective action?  He was looking in his flight bag for some charts and didn’t realize they were losing altitude until just before they hit the water.

When faced with an operational distraction, we have four choices in selecting how to deal with it.  We can either ignore it, delay dealing with it, delegate responsibility to someone else, or handle the problem.  Radio communication problems usually fall into the ignore column.  I once took off in a Cessna 172 only to discover that at low altitude over congested areas both radios were picking up broadcast stations.  After I determined that there was nothing I could do to get rid of it and that I could still hear ATC over the public stations there was nothing I could do except ignore the problem.  A door opening on takeoff also falls into the ignore category.  In many aircraft there is not much you can do in flight to resolve the situation, yet over and over people crash, land gear up, etc. all because of a problem that essentially needed to be ignored until they were safely back on the ground.

Almost anything that occurs during a critical portion of the flight such as takeoff and landing, needs to be delayed.  In jet aircraft, the response to an engine fire light on takeoff depends on where in the takeoff the aircraft is.  Below decision speed, an engine fire light elicits an immediate abort.  A few seconds later, that same light should result in nothing more than a simple statement noting that it is on, and the command, “Continue the takeoff!”  Many aircraft have been destroyed by crews who got so distracted by the fire light or some other light on takeoff that they forgot to fly the aircraft.  The only priority at that point is to get the aircraft up to a safe altitude where the emergency can be handled.

Occasionally there are operational distractions which can be delegated to someone else.  Even someone flying as single pilot with one or more passengers may find an opportunity to get some help from a passenger.  Almost anyone can help hold a chart or write something down.  With only a little training, most people can learn how to select a frequency on the radio.  I remember one instance where I should have asked for help from a passenger but didn’t.  I was flying a Cessna 414 back from Mexico to Tucson with the CEO as the only passenger.  He actually had a private pilot’s license but didn’t normally express any desire to sit up front.

It was one of the few night IFR flights I had experienced in that part of the world, which almost never has bad weather.  As I was approaching the border I began to smell smoke in the cockpit.  Soon I could actually see smoke coming up from the circuit breaker panel on the left side of the cockpit.  I began to isolate the various buses and soon determined that the problem was with the cockpit lighting circuit breaker.  The good part was that I had not lost any critical flight or navigation instruments.  The bad part was that I was reduced to flying with the regulation D cell flashlight in my mouth part of the time as I tried to keep the plane right side up and headed in the right direction while getting ready for and completing the approach.

As he exited the airplane in Tucson, my passenger, in the ultimate understatement, asked me, “Did you have a little trouble tonight Jay?”  I would have answered but my mouth was still stuck in the shape of an “O” from holding the flashlight.  Although it was my responsibility to fly the plane, if I had requested that he come up in the cockpit my life would have been a little simpler, and my mouth a lot smaller!

Finally, there are some operational distractions that simply have to be handled right now.  The second item on the NASA study of airline operational distractions was malfunctions, and there certainly are a significant number of problems that need attention right now.  However, no problem will be improved by flying into the ground, so be very careful that you don’t get so fixated on solving the problem that you forget to fly the aircraft.

NEVER RELAX

©Jay Hopkins – All rights reserved

Originally published in Flying September, 2007

It is one of the dreams that pilots dream. An airplane, a full tank of gas, a clear sky, no where in particular to go and no schedule to get there. Head out to the airport, “kick the tires and light the fire.” Just you and a friend enjoying the view and the freedom, escaping at least for a few hours from the madcap rat race rushing in every direction below you.

Cory Lidle and his flight instructor learned that dreams can turn into nightmares in less than a moment, just as just as thousands of other pilots have learned before them. The NTSB has not completed their study of this accident, so it is too early to try to analyze every detail of how this accident might have happened. However, the NTSB has released preliminary information that can help others avoid the same tragic outcome.

At this point we know that they had taken off from Teterboro, NJ, and were flying along a VFR corridor around Manhattan that lies beneath the Class B airspace over New York. Aircraft in the corridor generally have to stay below 1,100’ MSL, so the overcast ceiling at 1,800’ should not have been a factor, and the 7 miles visibility made it a fine day for a sightseeing flight around the New York City area.

The NTSB reports that Cory and his instructor had already flown over the Statue of Liberty when they turned north up the East River. Eventually they reached the end of the corridor where they had to turn around to avoid entering controlled airspace. Doing a 180 degree turn in a small airplane is usually no big deal—coordinated aileron and rudder, with a little back pressure to compensate for the loss of lift in the turn, and pretty soon you are headed the opposite direction. But Cory and his instructor were not flying at a normal cruising altitude with no obstructions. They were flying 800’ above a river with tall buildings on both sides of the river.

Preliminary information shows that they were flying up the east side of Roosevelt Island when they began their turn to the west, giving them a radius of only 1,700’ in which to complete the turn while remaining in the corridor. The NTSB has calculated that this would have required a bank angle of 53 degrees at their cruising speed of 93 knots, producing a load of almost 2 Gs on the airplane. The airplane did not successfully complete the turn, lost altitude and struck a building along the river.

We will probably never know how much planning they did before this flight. On similar sightseeing pleasure flights that I have made in the past, the planning was minimal. Part of the pleasure of this kind of flight seems to be the ability to experience the joy of flying without all the course plotting, weather analyzing, weight and balance computing and flight plan filing that precedes a “serious” flight.

There is a tool called AESOP we can use to carefully assess the possible risks on even a local sightseeing flight without taking much time or reducing the relaxed atmosphere of the day. AESOP helps us take a moment to focus on the various risk possibilities of the flight and plan an appropriate risk mitigating response:

Aircraft – What is the performance of the aircraft we are going to fly? Are there any mechanical problems? Is there sufficient fuel on board?

Environment – What is the current and forecast weather along our planned route? If the weather is marginal, is there a good fall back location in case things go sour?

Obstacles – Is there anything else that could cause us a problem doing this flight with this equipment?

Personnel – How are all crewmembers doing? Did anyone not get a good night’s sleep? Is anyone not feeling well? Has everyone had a meal recently?

Situation – Even though the “S” is in the middle of AESOP, it is referenced last as an assessment of the overall situation. Are we:

            “Green – Good to go?”

            “Yellow – Ragged edge?”

            ”Red – No go (or stop)?”

A pilot pausing for a moment to do AESOP before a sightseeing flight around Manhattan in conditions similar to those experienced by Cory would probably not come up with any risk factors until reaching Obstacles. At that point, the pilot might realize that it was important to consider how to maintain clearance from the controlled airspace, and how to reduce the risk of maneuvering within tight corridors surrounded by buildings. This discussion would hopefully cover the importance of keeping the speed slow during a course reversal to minimize turn radius, while starting the turn on the downwind side of the corridor to maximize the distance available by turning into the wind.

It appears that Cory would have had an additional 400’ turning radius if he had started his turn over the extreme east shore of the river. This would have provided almost 25% more space to accomplish the turn. A much tighter turn radius would have been possible if the airplane was slowed to a comfortable margin over stall with about ten degrees of flaps. Even more space would have been available if the turn was made from the other shore into the 13 knot east wind.

It is easy to get complacent on any flight, particularly a local sightseeing flight. The beauty of AESOP is that it helps to maintain your focus without taking an excessive amount of time. In the minute or two it takes to run through AESOP, you will have an opportunity to confront the possible risks that have led to accidents when other pilots failed to consider them, such as:

  • High density altitude in relation to high gross weight
  • Potential changes in the weather
  • Endurance in relation to headwinds
  • Not having sufficient rest or food before the flight
  • Potential icing or mountain turbulence

AESOP is also a powerful tool a pilot can use to “buy a minute” when unanticipated events occur and things seem to be spinning out of control. In a situation like that, it is easy to make a snap decision without carefully considering all the options. There may not be much time, but usually the pilot can take at least a minute or two to use AESOP to assess all the risks he is facing and the resources available to respond to those risks. Often the use of AESOP will lead to an awareness of risks the pilot had not thought of or resources he had not considered. AESOP is such a powerful tool that many of my corporate Error Prevention clients such as Lockheed Martin Space Systems require their personnel to use a modified version of AESOP before any task or operation.

Flying just for the fun of it is a wonderful experience, but the risks inherent in flying do not go away just because you are only there to have a good time. In fact, a relaxed situation often leads to a loss of situational awareness, which in turn can lead to disastrous consequences that can spoil the fun of any flight, or worse. Before every flight and when anything unanticipated happens, use AESOP to assess the risks and the resources available to deal with those risks. You will likely come up with something almost every time you use it, and every once in a while it will literally “save your bacon.”

MASTER OF ILLUSIONS

©Jay Hopkins – All rights reserved

Originally published in Flying September, 2002

Everyone loves a magic show. For some reason, the idea that things aren’t really as they seem, that we can be fooled by our senses, is exciting to most people. However, for a pilot an illusion can be serious business. With at least thirteen different illusions working to fool us into thinking things are different than they really are, it is important that a pilot be the master of each of these illusions, so that he won’t be fooled into making the wrong response or even into losing control of the aircraft.

Most illusions can be traced to the relationship between our three sensory systems. The motion sensing system of our inner ear, the visual system and the position sensing system which uses the nerves in our skin and muscles all work together to tell us what our body is doing and which way is up. As long as we are firmly attached to terra firma these systems work well together to provide us accurate information about what our body is doing. In flight, however, we are subjected to forces we don’t usually experience on the ground. Add in restrictions to visibility which knock out the information from our visual system, and we are sitting ducks for illusions.

Our susceptibility to illusions has been put to beneficial use in advanced simulators equipped with a motion base. Many people assume the simulator is replicating the motion of the plane. This is actually not true. The simulator moves in ways to make you feel what you would feel if you were in the plane doing whatever you are doing. The visual system in the simulator completes the illusion. For example, as the pilot advances the thrust levers for takeoff, the simulator immediately begins to tilt back and rise vertically. The pilot inside the simulator can’t tell what it is doing and this motion pushes him into the seat and makes him feel like he is accelerating down the runway. Similarly, when the pilot is braking after landing, the simulator tilts forward to throw him against his harness and make him feel as if he were slowing down in an aircraft.

GRAVEYARD SPIN

The fact that the first two illusions start with the word “graveyard” gives you some idea of the typical outcome after falling prey to these illusions. They both are a result of the fact that in a prolonged spin or turn, the fluid in the semicircular canal of the pilot’s ear aligned with the axis of the spin or turn will stop moving. In the graveyard spin, the deceleration that occurs when the pilot recovers to level flight starts the fluid moving again, giving the pilot the illusion he is spinning in the opposite direction. The disoriented pilot will return the aircraft into the spin he just recovered from.

GRAVEYARD SPIRAL

The loss of motion in the canal during a constant rate descending turn can cause a pilot to think he is in a wings level descent. When the disoriented pilot pulls back on the controls to stop the descent, he tightens the spiral and increases the rate of altitude loss.

CORIOLIS ILLUSION

Once again, the eventual lack of motion in the canal, in this case during a prolonged constant rate turn, is the instigating factor. If a pilot makes an abrupt head movement, he may start the fluid in more than one of the canals moving, making him feel like he is turning or accelerating in a different axis. The disoriented pilot will attempt to “recover” from the perceived rotation, and in doing so may put the aircraft into a dangerous attitude.

INVERSION ILLUSION

If a pilot makes an abrupt change from a climb to level flight, it can make him feel as if he is tumbling backwards. The disoriented pilot pushes the aircraft into a nose low attitude, which can intensify the illusion.

ELEVATOR ILLUSION

If an updraft causes an abrupt vertical acceleration, it can make a pilot feel like he is in a climb. The disoriented pilot will push the aircraft into a dive. A downdraft can create the opposite effect, with the disoriented pilot pulling the aircraft into a climb or even into a stall.

SOMATOGRAVIC ILLUSION

The rapid acceleration during takeoff or a go-around can make a pilot feel as if the aircraft is in a nose high attitude, causing him to push the nose down with disastrous results near the ground. Likewise, a sudden deceleration caused by a rapid reduction of power can cause the pilot to pull back on the wheel.

FALSE HORIZON

A number of visual conditions such as a sloping cloud deck, a dark night with ground lights and stars, or even just an obscured horizon can cause a pilot to attempt to level the aircraft with a false horizon.

AUTOKINESIS

If a pilot stares at a stationary light, after a short period of time the light will appear to move. The disoriented pilot can lose control of the aircraft if he attempts to keep the aircraft aligned with the light.

One example of the disastrous results of falling for one of these illusions occurred when the captain of a commuter airliner initiated a missed approach in poor visibility while still looking out the window to try to spot the runway. The somatogravic illusion caused him to feel like the aircraft was pitching up excessively and he pushed forward on the control wheel to “correct” for the nose high attitude. Even though the copilot tried to warn him, they were at such a low altitude that they impacted the ground a few seconds later.

There are a number of ways a pilot can avoid falling prey to these illusions. We are at risk primarily at night and in instrument conditions when the visual element of our orientation is eliminated. The most basic rule is to avoid getting into instrument conditions unless you are instrument certified and current. When in instrument conditions, keep a good scan going and fly as smoothly as possible. Don’t make any control inputs unless you are looking at the attitude indicator. Keep all turns at or below a standard rate turn and make gentle pitch corrections. Also try not to make any sudden head movements, especially down or to the rear. If you have a reliable autopilot, engage the autopilot before looking for charts or doing anything else that might distract you from your scan and allow an illusion to play its tricks on you.

VISUAL ILLUSIONS

If you were keeping track, you have noticed that I have only covered eight illusions so far, even though I said there are thirteen. The final five illusions are strictly visual illusions associated with landing.

RUNWAY WIDTH ILLUSION

Each pilot has a mental image of what a runway should look like based on the size of the runways he normally operates from. When approaching a runway significantly narrower than what he is used to, the pilot will feel like he is higher than he actually is and may fly a dangerously low approach. On the other hand, a much wider runway makes the pilot feel like he is lower than he really is and can result in a high approach, a high flare and a hard landing.

RUNWAY/TERRAIN SLOPE ILLUSION

In an effect similar to the runway width, a pilot approaching an upsloping runway will think he is higher than he actually is, while a downslope will have the opposite effect.

FEATURELESS TERRAIN ILLUSION

A pilot approaching a runway at night over water or a dark area with no lights may feel that the aircraft is higher than it actually is and fly an approach below the normal glide path.

ATMOSPHERIC ILLUSIONS

Atmospheric haze creates the illusion that the pilot is farther from the runway than he really is, while rain on the windscreen makes the pilot feel like he is at a higher altitude. In either case the pilot may fly a lower than normal approach. As the pilot penetrates a fog layer on the approach it can make him feel like he is pitching up and cause him to steepen the approach.

GROUND LIGHTING ILLUSIONS

A pilot approaching a runway at night with few or no lights in the surrounding area can be led to believe he is closer to the runway than he actually is. Also, straight lines of lights along roads can be mistaken for a runway.

The key to avoiding these visual illusions, besides maintaining a general awareness of how they work, is to carefully familiarize yourself with all available information about the airport and to make use of all available navigational aids to improve your situational awareness. Once again, it is important not to make any sudden or abrupt control inputs. Finally, if it becomes evident that you have fallen prey to an illusion, go around and then use the information you have gathered to compensate on the next approach.

LOST COM

©Jay Hopkins – All rights reserved

Originally published in Flying January, 1997

It has probably happened to every pilot at least once. My turn came during a time when I was flying charter in Learjets. So many of our flights were at night that I was beginning to think Learjets couldn’t fly in the daylight. On this particular flight we were on our way back to Houston from Atlanta at 3 am. At that time of the night there isn’t a lot of chatter on the radio, so it is possible to go quite a while without hearing anything. Still, as we cruised peacefully through the night skies, it gradually occurred to me that it had been a long time since we had heard anything. Finally I decided to give ATC a call to make sure the controller hadn’t fallen asleep. His response shocked me. During our last transmission our mike button had stuck. Ever since that transmission we had been jamming the frequency, and we had been totally out of communication with center.

When most of us think of loss of communications, we probably think of the classic situations like a radio failure, a total loss of electrical power, or a stuck microphone. Analysts at NASA’s Aviation Safety Reporting System examined the causes and effects of a loss of communication capability, and published their findings in an ASRS Directline report. It turns out there are many ways pilots can find themselves out of communication with ATC. For example, the pilot can set-up the audio panel incorrectly. The volume control on the radio can be set too low. During a change of frequency, the controller can assign the wrong frequency, the pilot can tune the wrong frequency, or the pilot can forget to switch to the new frequency. The pilot can use the wrong radio. The ATC facility can experience radio failure. The frequency can be so congested the pilot can’t get though. And of course, the pilot can fall asleep. Pilots have been incommunicado for as long as an hour, but the average length of time is about 7.5 minutes.

Over half of all interruptions to communications occur because the pilot didn’t set the radio or audio panel correctly. Digital radios with their flip/flop frequency selection are a great tool for the pilot, but they also introduce a new level of complexity into the cockpit which can lead to errors. One pilot switched radios because of a loud noise on the radio he was using. In the process of switching he inadvertently left the approach control frequency on the preselect side of the radio he was switching to. The controller had to delay seven other aircraft during the time it took the pilot to realize his mistake and call approach.

An instructor reported a loss of communication due to congestion on the frequency. “There were many calls at the same time to other aircraft by the tower, so I turned off the speaker switch to tell the student to descend to pattern altitude.” The speaker was only supposed to be off for a moment, but the instructor got busy looking for traffic and forgot to turn it back on. Finally aware it was far too quiet in the cockpit, the instructor discovered the speaker switch was still off. The tower controller reported he had been calling them for five minutes.

Aircraft radio problems or complete failure of the radios were the second most prevalent cause of a loss of communication, accounting for one third of all reported cases. Radio problems were particularly prevalent in general aviation aircraft, which often have older radios. Hand-held portable radios were used on several occasions to reestablish communications after radio failure. However, one pilot discovered that the digital frequency windows contain a trap for the unwary pilot. He experienced total electrical failure, and after trying to get his radios back, he remembered that he carried a portable transceiver for just such an occasion. He pulled it out, connected the headset, and attached the radio to the external antenna cable. You can imagine his disappointment when he went to enter the desired frequency and realized that it was unavailable due to the inoperative radio panel. He tried 121.5 but got no response, so he waited until he broke out into VMC and then located an airport visually. His handheld unit was useless because he hadn’t written the frequency down.

A blocked frequency due to a microphone, radio transmitter or audio selector panel stuck in the transmit mode accounted for about 15% of all communication problems. In this situation there is an additional factor—everything being said in the cockpit is also being transmitted over the frequency selected and pilots in the throes of a communication failure may not use the best language. After a pilot reestablished contact following a stuck mike, the controller asked the pilot to contact the facility supervisor by telephone. It seems that the pilot had made some comments about his aircraft and radios while he was in the process of figuring out the problem. The supervisor stated that they had to go to a backup frequency because of the pilot’s language!

One interesting aspect of this problem is that the phase of flight in which the loss occurs varies greatly between general aviation and air carrier operations. For airline pilots, the problem is intimately tied to the boredom experienced during the long periods of time spent in cruise flight and the reduced levels of attention this may produce. Perhaps the ultimate example of this was the crew of three who were eating dinner and failed to hear repeated calls from ATC, including some relayed from other aircraft. They managed to arrive overhead Atlanta (their destination) still level at 35,000 feet!

General aviation pilots don’t have as many communication problems during cruise flight, perhaps because they often fly single pilot and thus must maintain a much higher level of awareness than crew members who fall prey to the Copilot Syndrome and assume someone else is listening to the radios. It is during the increased workload of the approach and landing phases that the general aviation pilot is more likely to experience communication problems. It was also discovered that, as with accidents, the pilot with low time in type is much more likely to have a problem with communications. It is very easy to picture the inexperienced pilot being able to handle the radios during the low workload of cruise flight but making mistakes during the high workload of the approach and landing phase.

Since over half of all communication problems are related to pilot error in operating the radios, and since many of these are related to inexperience in the aircraft, we can have a significant impact in reducing these types of problems. The first and most obvious advice is not to operate an aircraft until you are completely familiar with the audio system. Pilots are known to jump in an unfamiliar aircraft without an adequate checkout, and even if the pilot does spend some time getting familiar with the aircraft, he may not dedicate much of that time to the radios. After all, radios are basically all alike. You turn them on, you tune them, and then you push the mike button. However, throw in an audio panel and some digital frequency swapping radios, and all of sudden things are not as easy as they seem, especially in a high traffic environment with lots of frequency switching required.

Proper flight planning is critical in the communications arena. The more frequencies you can note ahead of time and have available for instant access, the less time you will waste scrambling through charts trying to find the frequency you need. As the pilot who couldn’t retrieve his frequency after a power failure discovered, you should write down each frequency you use in the order you use them. I simply write the frequencies in a column, starting with my original clearance. Each time I receive a new frequency I add it to the bottom of the list, so I always have the current and previous frequency available.

Finally, it is important to maintain an adequate level of situational awareness. Tuning radios may not be the most exciting thing we do as pilots, but the consequences of a mistuned radio or audio panel can be serious, both for ourselves and the aircraft around us. Even when things get really busy, take the time to focus on the task of getting the proper frequency into the correct radio and then check to make sure it is right. And remember that if your communication problem is due to a stuck mike, every word you are saying is being transmitted for everyone on the frequency to hear.

LEARNING HOW TO DO NOTHING

©Jay Hopkins – All rights reserved

Originally published in Flying June, 1994

It was a beautiful Kentucky morning as the pilot and three passengers arrived at Bowman Field in Louisville for a flight to Athens, Georgia.  The light from the rising sun illuminated the bottom of the broken clouds at 7000 feet.  The temperature was 53 degrees, cool enough to be invigorating but temperate enough to be comfortable, with a gentle breeze flowing almost directly down the active runway.  In short, it was the type of morning that makes you glad that you are going flying.

Soon the preflight of the Beech Sierra was completed and everybody was onboard.  The pilot taxied to the end of runway 19 and at 7:29 am was cleared for takeoff.  He smoothly added power and the aircraft accelerated quickly in the cool morning air.  At just the right moment he gently pulled back on the control wheel and the aircraft lifted easily into the air.  Suddenly the familiar flow of events was shattered by a popping noise followed by the loud rush of flowing air.

The right door had come open.  A minute after being cleared for takeoff the pilot radioed the tower and reported, “Bowman we have a door open.”  The tower cleared them to land on any runway and gave the winds.  It appears that the pilot couldn’t hear the tower over the noise of the open door, because 20 seconds later he again told them he had a door open and the tower repeated the option to land on any runway.  Several witnesses observed the aircraft flying at about 150 to 200 feet above the ground when it banked steeply to the left towards the approach end of runway 24.  It then struck the top of a large tree and continued to the ground in a left wing low, nose down attitude.  Only one passenger sitting in the right rear seat survived.

We will never know how often doors pop open on takeoff.  Most of the time it is merely an inconvenience and maybe an embarrassment to the pilot as he has to return to the airport to close the door securely.  But the records show that at least 50 times between 1982 and 1988 a door opening on takeoff resulted in an accident and 14 of those involved fatalities.

The best way to avoid a crash from an open door is to make sure the door is securely closed in the first place.  In our rush to get going our minds are usually on checklists, runways, routes and weather.  Something as mundane as closing and checking the door can easily become a ritual response completed without any care or attention.  Some passengers may try to be helpful by closing the door themselves and it may even look like they know what they are doing.  But unless they are pilots they usually will not know how to work the handle for the primary latching mechanism, and won’t even be aware of secondary latches.  So make sure only you handle the door closing responsibilities and slow down enough to pay attention to what you are doing both as you close the door and as you check it for security.

Even the most careful pilot may still find his takeoff interrupted by the loud rush of air as a door pops open.  The door usually opens at the most critical moment during the takeoff just as the pilot is rotating to the takeoff attitude or shortly after leaving the runway.  The sudden loud noise is very distracting and on top of that the pilot may immediately start thinking about how it could have happened and how he can quickly rectify the situation so the flight can proceed with minimum delay or embarrassment.  Since the least impact will occur by closing the door in flight, some pilots do not consider immediately aborting the takeoff even if sufficient runway remains to safely stop.

One of the most harrowing incidents I ever had in an aircraft involved an aborted takeoff due to an open door.  I was flying a Seneca II for a corporation and was departing Aspen during the winter.  The Seneca has a known problem with the nose baggage door opening on takeoff.  One reason is that as the door handle is turned, it will get very stiff and appear to be latched before it is fully engaged.  Because of this I had a standing rule that no one was to touch the nose baggage door except for myself.

On this particular day I had already loaded the nose baggage compartment and ensured that the door was securely closed.  One of my passengers had neglected to give me a briefcase and decided to put it in the nose baggage compartment.  I was occupied elsewhere and had no idea he had opened and shut the door himself.  We were just rotating for takeoff when the nose baggage door flung open.  Fortunately, there was sufficient runway remaining to abort the takeoff, but the brakes were so hot I could smell them as we came to a stop close to the end of the runway.

If the pilot does not abort the takeoff, the alternative course of action is to do absolutely nothing.  This has to be the hardest thing for a pilot to do.  We are trained to react instantly to a problem.  Instructors are famous for closing the throttle or simulating some other problem and then expecting an immediate and correct response to the situation.  The simple fact is that some problems are best handled by inaction or very little action.  Except for multi-engine aircraft that may become unflyable after a nose baggage door opens in flight, most light aircraft exhibit no drastic deterioration in performance or controllability from an open door.  The typical operating handbook states that the flight characteristics of the airplane are not affected by an open door except for a reduction in the rate of climb.  The pilot is also usually advised to ask a passenger to hold onto the door after landing so it doesn’t swing open and get damaged.  In the case of the Beech Sierra, a Beechcraft Safety Communique was issued advising only shallow turns not to exceed 30 degrees bank.  It also states that airspeed and altitude indications just above stall may be in error on the high side.

Accident reports indicate that pilots typically spring into action as soon as the door opens.  In one typical case, a surviving passenger who had been in the right front seat stated that as soon as the door opened the pilot leaned across him and tried to close the door.  This is with the aircraft only about 50 feet above the ground!  Anyone that close to the ground has no business doing anything except flying the airplane, and the distraction of trying to close the door could easily result in loss of control and impact with the ground.  Worse than that, in many planes any attempt to close a door in flight is useless due to the suction on the outside of the door.  That’s why it popped open in the first place.

Once the pilot realizes he is not going to be able to close the door, he typically will decide to return to the airport and land.  Since this is going to delay the flight he wants to get it over with as soon as possible, so he does the worst possible thing and initiates a steep turn at low altitude.  In the case mentioned above, as soon as the pilot realized he couldn’t close the door he announced to the passengers that he was going to return to the airport.  Then, having achieved all of 200 feet above the ground he banked sharply to the right followed immediately by a steep bank to the left as he attempted to do a crop duster turn.  The airplane crashed just after he started the left turn.

So if one of your takeoffs is interrupted by the loud rush of air and there is sufficient runway remaining to safely stop the aircraft, abort the takeoff immediately, exit the runway, stop and carefully close the door.  If there is not sufficient runway remaining when the door opens, just continue the takeoff straight ahead.  The only change to your normal procedures should be to keep your speed slightly above normal, and this is primarily to ensure you don’t get slow.  It is important to climb to pattern altitude and to fly a normal pattern.  Although you may want to get back on the ground as soon as possible, there is absolutely no operational reason to do so.  In fact, since your usual routine has been broken and you are probably somewhat distracted by the door, take a little extra time to be sure you complete all checklists.  That way you can avoid the embarrassment of the pilot who did everything right when the door opened in flight except that he forgot to lower the landing gear when he returned for a landing!

KNOW YOUR AIRPLANE

©Jay Hopkins – All rights reserved

Originally published in Flying January, 2001

The pilot and photographer took off in a Twin Comanche from Greenville, North Carolina, at about 11 A.M. for an aerial mapping flight at 8,000 feet just north of the Greenville airport. As you would expect for an aerial photography flight, the skies were clear. Two hours later the job was done and the pilot prepared to return to the airport. Because he was only ten miles from the airport, he decided to lower the landing gear to facilitate their descent. When he placed the landing gear switch in the down position, the amber gear up light went out, but there was no increase in noise or drag, no pitch change to indicate the gear was extending, and the green gear down and locked light did not illuminate.

The pilot tried the switch several more times with no success. He also checked the circuit breakers and confirmed that the instrument lights were not on, causing the gear indication lights to dim. The pilot next got out the normal checklist and confirmed that he had followed the correct procedure. Finally he referred to the emergency gear extension procedure on the emergency checklist. As instructed by the checklist, he removed the gear access door between the pilot and copilot seats, “removing the handle that would be used to pump the landing gear down.” He also raised the red handle to disengage the motor from the shaft, observing that the motor was quite warm to the touch. He observed that when he raised the red handle, the shaft that it was mounted on moved freely.

The pilot reported that as he “pumped the gear down, the shaft would move laterally in the compartment along with some up and down movement. The pressure on the hydraulic pumping mechanism would at some times be hard and other times quite easy to move. The green light never did come on. I must have pumped the gear handle 200 to 300 times in an effort to assure that the gear was down and locked.”

All this time the pilot was also in contact with the FBO for technical advice, and he did a fly-by four times to try to determine the position of the landing gear. The people on the ground reported that as he pumped the emergency gear handle they could see the gear moving up and down, but that it never went all the way up or down. With less than half an hour of fuel remaining, the pilot decided to attempt a landing and requested that the fire department be standing by. While on base leg, the pilot had the passenger unlock the door and push it open slightly to preclude the door jamming on landing. The final approach was normal, with the gear switch in the down position but no green light. As he started to flare he brought the throttles to idle, feathered the propellers, and pulled the mixtures to idle/cutoff.

As the plane touched down,  the gear collapsed and the aircraft settled to the runway. They slid down the center of the runway, drifting off to the left slightly. As they were sliding down the runway, the pilot turned off the battery and magneto switches. As soon as the plane came to a stop, he instructed the photographer to deplane and immediately followed him. Neither the pilot nor the photographer suffered any injuries.

At first glance it would appear that this pilot handled the failure of the gear to extend about as well as anyone could. He made sure he was flying the airplane at all times, he referred to the checklist and carefully worked his way through the emergency gear extension procedure. When that did not seem to be successful and he was running short on fuel, he carefully planned and executed a successful gear-up landing. There was only one small problem. The Twin Comanche has an electric, not a hydraulic, landing gear system. The last step of the emergency landing gear extension procedure is to push the handle all the way forward to fully extend the gear. The pilot fell prey to something I call Strength of an Idea. It is evident that he had experience with aircraft with hydraulic landing gear systems. When he took out the emergency gear extension handle, he even referred to it as “the handle that would be used to pump the landing gear down.”

With the idea that he was dealing with a hydraulically activated landing gear system firmly in mind, the numerous inconsistencies he encountered never had a chance at opening his eyes to the truth. When he removed the emergency gear extension access panel, he saw a small electric motor, a few wires and a drive shaft, not hydraulic lines. The emergency extension handle was inserted into a crossbar that transmitted the force of the gear motor to the landing gear. It in no way resembled a hydraulic pump. Each time he pushed and pulled on the handle it would get hard and then easy to move. This is because each time he pushed on the handle he was extending the gear, and every time he pulled back on the handle he was raising the gear. He must have been exhausted after raising and lowering the gear over 200 times!

Now for the rest of the story. The pilot had recently been hired by the aerial photography company. He had about 9,000 hours total time, 6,000 in multiengine aircraft, with ATP and CFI ratings. However, he had just over seven hours in the Twin Comanche, all acquired in the previous thirty days. Most of the rest of his time involved instructional flying. It is obvious that this individual either did not spend much time studying the Twin Comanche systems, or he skipped the part on the landing gear. Thus it was easy to miss the fact that the last step in the emergency landing gear extension procedure is to push the emergency extension handle forward as far as it will go, not to pump the handle. While his arms got a good workout, it was all in vain.

Unfortunately this story taken from the pages of the Comanche Flyer, which is published by the International Comanche Society, is not unique. Even though the Comanche has an extremely simple landing gear system and emergency gear extension procedure, pilots manage to land Comanches gear up with sickening regularity. The previous issue of the Comanche Flyer contained a similar story, only in that case it involved an instructor with 14,000 hours but no recent Comanche experience providing transition training to a 500 hour pilot with no complex aircraft experience. They experienced a total electrical failure due to the alternator switch being in the off position and couldn’t get the gear down. Another issue told the story of a pilot who had the engine fail due to fuel starvation and crashed into a clearing in the woods only a mile short of the runway with over 2.5 hours of fuel in tanks other than the one he had selected.

What is the common link in many of these stories? The pilot was new to the aircraft, often with less than ten hours in the aircraft, and he didn’t take the time to adequately learn everything he needed to know. Bill Turley of Aircraft Engineering in Bartow, Florida, confirms this astounding lack of systems knowledge. “Seventy-five percent of the owners can’t tell you how the gear works. I’ll ask them, ‘Is it hydraulic or mechanical,’ and they say, ‘Hell, I don’t know!’”

Flying an aircraft, whether you own it or rent it or get paid to fly it, carries with it certain responsibilities. While flying may be just an enjoyable hobby to many pilots, that does not eliminate the time and effort required to acquire and maintain the necessary knowledge and skills to be a safe pilot. Last month I talked about maintaining competency to match your type of flying, or limiting the conditions you fly in to match your skill level. There is no way to “adjust” your use of aircraft systems to your skill level. You will need to use most or all aircraft systems on every flight, and there is no way to predict when you may have to deal with a system problem or failure. Next month’s article will detail a plan for learning and refreshing the information and skills necessary to safely operate any aircraft, from a simple two seat trainer to the most complex pressurized twin.

JUMPING THE GUN

©Jay Hopkins – All rights reserved

Originally published in Flying October, 1998

It is amazing the impact one little word can have. Take a clearance and add the word “expect” to it and it is no longer a clearance at all. The significance of that one word can be lost, leading to unexpected actions on the part of the pilot. Originally the word “expect” was added to the controller’s handbook in a well intentioned effort to provide pilots with information about what would be coming up ahead of time so they could plan their actions in advance. It was typically used with specific information, as in “expect 7,000 in 10 minutes”. While this type of communication undoubtedly did achieve its intended purpose of alerting the pilot ahead of time, it also contributed to a large number of altitude deviations as pilots mistook the expected clearance for the real one. This problem is particularly dangerous because this type of communication is typically used when the pilot and controller workloads are highest and the potential for a traffic conflict is greatest.

The controller’s handbook now encourages the controller to inform the pilot about when he can expect a climb or descent without actually stating the altitude but instead using the phrases “expect higher” or “expect lower”. While this has helped to reduce the confusion resulting from these types of communications, the word “expect” is still often used with specific information in a manner which allows the pilot to mistake an expected clearance for a real one.  A report in the ASRS Directline listed some of the more common phrases such as: expect vectors; expect visual approach; expect ILS Runway two-seven; expect departure after two more landings; expect no delay; expect a certain altitude ten minutes after departure; expect to hold at; etc. Pilots are also frequently told to expect certain altitudes, headings or speeds on instrument charts such as Standard Instrument Departures (SIDS) and Standard Terminal Arrivals (STARS). These communications can be especially confusing when they contain both mandatory and expected values.

Altitude deviations are still one of the most common results of misinterpreting a communication containing the word expect. One aircraft was cleared to descend to flight level 390. The pilot asked the controller if the descent was at his discretion. The controller responded that it was and added that he could expect to cross the next intersection at 11,000 feet and 250 knots. The flight crew misinterpreted this as a clearance and started their descent resulting in a loss of separation with an aircraft at flight level 370. While the controller was trying to be helpful, he could have avoided the chance of a misinterpretation by not mentioning the expected clearance until the opposing traffic had passed.

Traffic conflicts can also result from a misunderstanding about whether an aircraft has been cleared for a visual approach. In a typical scenario, the controller asked the crew of a descending aircraft if they could accept a visual approach. The pilot responded in the affirmative, believing he was actually accepting a visual approach clearance at that time. He was told by the controller to descend to 4,000 feet and report the runway in sight. The pilot attempted to report the runway in sight to the controller but was delayed in doing so by other radio traffic on the frequency. He finally got through to the controller as he were approaching 3,300 feet in his descent towards the runway. The controller told him to climb back to 4,000 feet to avoid traffic at 3,000 feet.

It is interesting that in this case the copilot correctly interpreted the communication and tried to inform the captain, who was flying the aircraft, that they were descending below their assigned altitude. He called out “4,000 feet” as they approached that altitude, and as they continued to descend, informed the captain that they were cleared to 4,000 feet. Even after a call from approach about their altitude and another attempt by the copilot to convince him that they were below their assigned altitude, the captain was so sure he was cleared for the visual approach that he told the copilot to inform the controller they had the field in sight.

The combination of a clearance with expected clearance information can be especially confusing. One STAR says to “cross GLAND at 250 knots and expect clearance to cross at 10,000 feet.” Both the pilot and the copilot of an aircraft misread this as, ” expect clearance to cross GLAND at 10,000 feet and 250 knots.” The crew reported that when the controller cleared them to cross GLAND at 10,000 feet without any stated speed restriction, they discussed the clearance and decided that, “since the controller did not give them a speed restriction, none was required.” When they checked in with the approach controller his first question was about their airspeed, which was forty knots too fast.

These types of miscommunications can also happen on the ground. A plane was holding short of Runway 17R at DFW Airport. The pilots reported later that the tower controller was “extremely busy giving continuous run-on instructions with no gap to allow for acknowledgements.” They thought he told them to taxi into position and hold behind the air carrier aircraft on the runway. Shortly after they taxied into position the controller said, “Now you are cleared into position and hold—I told you to expect position and hold”.

The safety of our air traffic control system is predicated on pilots doing what controllers expect them to do. Anytime an aircraft deviates from its clearance the potential for catastrophe is there. This being the case, effective communication between controllers and pilots is essential, yet reports of deviations submitted to the ASRS cite communication problems more than any other cause. Hopefully controllers are continuing to work on developing standard phraseology which minimizes the chances of misinterpretation. Obviously the word “expect” needs to be used with care and perhaps even restated for emphasis whenever it is used.

Pilots need to be alert for communication traps like these. Anytime you hear or see “expect” take a few extra seconds to make sure you are clear in your mind exactly what you are supposed to do. This is especially important when information about what to expect is combined with a mandatory value. If there is the slightest bit of doubt in your mind about your clearance, ask the controller to confirm it. If his response doesn’t help or muddies the waters even more, ask again. If you realize you are going over the clearance in your mind trying to determine what to do, or if you are discussing it with a crewmember, then it is time to call the controller and get accurate information right from the source. If anything about a  clearance doesn’t make sense then you need to confirm it quickly

Be especially careful when there are other factors which might make a miscommunication more likely such as fatigue, being in a hurry, heavy traffic, inexperienced crewmembers, or bad weather. Distractions such as these are often mentioned in ASRS reports detailing mistakes arising from miscommunications. Give the controller a quick call confirming what you are doing, especially when there has been a delay between the clearance and the action. A good example of this is a clearance to do something at pilot’s discretion. We are already required to report leaving an assigned altitude, but it is a good practice to also report any other significant changes in speed or direction of flight. At the very least you will enhance the controller’s situational awareness, especially if for some reason he has lost track of what you were supposed to do. But occasionally this extra little communication may alert the controller to a misunderstanding and allow him to clear things up before you deviate from your clearance.

Finally, carry a supply of ASRS Reporting Forms (available from ASRS, P.O. Box 189, Moffett Field, CA 94035) with you and send one in anytime there is a significant miscommunication. Even if you didn’t deviate from your clearance or cause a loss of separation, the information you provide, combined with the reports from other pilots, will help researchers identify and do something about the communication traps that affect every pilot’s safety.

INVISIBLE MENACE

©Jay Hopkins – All rights reserved

Originally published in Flying January, 1998

 

The assailant strikes without warning. The victim, which was humming along in perfect health, suddenly is sputtering on the edge of death. Without prompt action, the end is swift and final. Then the perpetrator melts away and leaves no trace of its presence, making this the perfect crime. The AOPA Air Safety Foundation’s General Aviation Accident Analysis Book lists 193 accidents between 1982 and 1988 that involved this assailant—carburetor icing. The study also lists 902 accidents due to “Power Loss For Unknown Reason.” Over 75% of these occurred in single-engine fixed-gear aircraft which are most likely to have engines susceptible to carburetor icing.

Carburetor icing has been a problem ever since the early days of aviation, yet even with the accumulated knowledge of years of experience with this phenomenon, pilots still fall prey to it. The major problem is that there is no way to predict when carburetor icing will occur. We can only list certain parameters which make it possible for ice to form in the carburetor. One key ingredient is moist air with a relative humidity of at least 50%. Since humidity that high is very rare here in Arizona, carburetor icing is not much of a problem for us. In other areas where the humidity rarely drops below 50%, carburetor icing is a constant threat.

The other variable is temperature, with carburetor icing possible anywhere from 20 degrees to 90 degrees F. It might seem counter intuitive to be worried about ice forming  on a hot day, but the design of the carburetor can reduce the temperature of the air as much as 60 degrees. This is caused by both the vaporization of the fuel and a venturi effect within the carburetor. However, even though carburetor icing is possible over such a wide range of conditions, it is most likely at temperatures around freezing with a relative humidity above 80%.

The indications of carburetor ice formation also vary widely. The pilot of an aircraft with a fixed pitch propeller may note a gradual reduction in RPM combined with a loss of airspeed. An engine with a constant speed propeller will experience a decrease in manifold pressure, again followed by a loss of airspeed if the condition is not corrected. As the ice continues to form, the engine may begin to run rough, although it is also possible for no symptoms to appear until the engine suddenly can barely run.

An example of the rapidity with which carburetor ice can form with catastrophic results occurred to a student pilot taking off on a beautiful spring day with a temperature of about 50 degrees. Engine start, taxi, and run-up all proceeded normally. The pilot took off and was climbing through 300 feet when the engine suddenly began to sputter. After checking everything else, the possibility of carburetor ice occurred to the pilot so he pulled on the Carburetor Heat knob. He then experienced one of the traps of carburetor icing—when the carburetor heat is applied, it starts to melt the ice into water which is drawn into the engine and makes it run even worse. In most situations when you do something that makes things worse, you want to immediately reverse that action. If pulling on the carburetor heat makes things worse, all you can do is hang on and hope that the ice melts while you still have enough altitude to recover. If you turn off the carburetor heat, the engine is going to quit soon anyway, and once it quits you won’t have any heat to melt the ice.

The effects of carburetor icing are more commonly felt upon closing the throttle for descent or after the plane has been descending for a while. If ice has been forming without any noticeable effect, when the throttle is closed the additional restriction in airflow from the ice will seriously affect engine operation or even cause engine failure. Ice is also much more likely to form and to be more serious with the engine at reduced power settings.

While the student pilot was able to recover full power before he ran out of altitude, another pilot was not so fortunate. He departed Santa Ana, California in a rented Cessna 150 bound for Catalina Island. The temperature was 69 degrees with a dew point of 49 degrees. These conditions can produce moderate carburetor icing at cruise power and serious carburetor icing with reduced power for descent. The NTSB reported that the pilot had flown to Catalina Island at an altitude of 4,500 feet with flight following from Coast Approach. As he approached the island, he was cleared to descend and advised that radar services were terminated.

Several minutes later the approach controller received a call from the pilot to “Catalina Traffic” that he had engine trouble and was trying to make it to the airport. The controller asked the pilot for his position. The pilot replied, “Position…I’m on the ah…side.” The controller asked the pilot for his destination airport and he replied “Catalina.” There were no further responses from the pilot.

A witness stated that he heard intermittent sounds of an engine accelerating, sputtering, and cutting out. A second witness observed the plane turning to try to clear high terrain. He lost sight of it as it descended behind a ridge line. A few minutes later another pilot reported a brush fire approximately two miles west of the airport. Fire department personnel found the wreckage of the aircraft on fire. The pilot had not survived the crash.

Carburetor heat is usually supplied by a heat exchanger which draws air from an alternate source across a portion of the exhaust system. With the engine at climb or cruise power there is plenty of heat to melt off any ice which has formed, even if it takes a little while to accomplish the task. With the power reduced for descent there is not nearly as much heat. Once the ice builds to the point that additional power is not available, there may not be enough heat to melt off the ice. The results can be particularly devastating after a simulated engine failure if the problem is not discovered until power is added at low altitude. At that point the simulated engine failure becomes a real one!

The key to effective use of carburetor heat is to always use full heat before a significant reduction in power, and to keep the heat on while the throttle is at or near idle. Even here in Arizona, with air so dry the probability of carburetor icing is nil, we still pull on the heat every time before we close the throttle. The use of partial heat should be avoided unless your aircraft is equipped with an induction air or carburetor air temperature gauge. It is actually possible to raise the temperature just enough to cause ice to form in conditions when it ordinarily wouldn’t be a problem.

If you experience any indication of loss of power or engine roughness, get the carburetor heat on immediately. If it makes things worse that means it is working, so fight the temptation to turn it off again. Even without any ice present, carburetor heat typically reduces the output of an engine by about 15% and may also cause the engine to run rough due to a richer mixture. If available, the power can increased to make up for the loss of rpm or manifold pressure, and the mixture can be leaned. There is no limit to how long carburetor heat can be used except that it generally should not be used for a prolonged period of time at takeoff or climb power settings as it may cause detonation or damage to the engine.

Be especially careful on long descents. Even with the carburetor heat on, check the response of the engine occasionally to make sure there will be power available when you need it. Unless you have a safe landing spot within gliding range, get the power back on at an altitude which will allow you to deal with any hesitation or lack of response. Always remember how unpredictable carburetor icing is and how fast it can strike, even when it is least expected.