Tuesday, February 24, 2009

Internal Combustion

On July 10, 2007, about 0835 eastern daylight time, a Cessna Aircraft Company 310R, N501N, part of the fleet operated by the National Association for Stock Car Auto Racing (NASCAR) corporate aviation division, crashed while performing an emergency diversion to Orlando Sanford International Airport, Orlando, Florida. The two pilots on board the airplane (a commercial pilot and an airline transport pilot) and three people on the ground were killed. Four people on the ground received serious injuries. The airplane and two homes were destroyed by impact forces and a postcrash fire. The personal flight was operating under the provisions of 14 Code of Federal Regulations Part 91 on an instrument flight rules flight plan. Visual meteorological conditions prevailed at the time of the accident.


Few things in aviation are more frightening to contemplate than an in-flight cabin fire, which is what the pilots of this Cessna 310 were apparently attempting to deal with. Most GA pilots don't give much consideration to what parts of the aircraft might provide a source of ignition nor how they would handle an in-flight cabin fire. As with all things in life, forewarned is forearmed and there are some important things to consider regarding in-flight fires. Contemplating the ingredients required for an in-flight fire is a good place to start, followed by knowing if your aircraft is equipped with a fire extinguisher and what type it is, inspecting the fire extinguisher during your preflight, knowing how to remove and use the fire extinguisher, and an awareness of how much time the average GA pilot might have to successfully deal an in-flight fire. To be fair, other factors in the above mentioned accident appear to involve the improper handling of inoperative equipment and circuit breakers, which I'll cover in a future installment.

This just in: To have a fire you need a source of combustible material, an ignition source that will get that material to its kindling temperature, and oxygen. A lot of things inside an aircraft will burn with the most obvious being fuel, but insulation on wiring, circuit boards, and other electrical components will combust when given the right sort of push. Heat from an engine, open flames, bleed air, and electrical sparks and resistance are all possible sources of ignition. Oxygen is widely available at no charge. Once a material reaches its kindling temperature, the source of ignition will probably no longer be required to keep the party going. Even so, the first step in fighting an in-flight fire is to remove the source of ignition. Always follow the checklist procedures in your FAA-Approved Aircraft Flight Manual, but a safe first step is to de-energize the electrical system - Turn off the battery master, alternator and/or generator.

The next step is to extinguish the fire and many, but not all GA aircraft are equipped with at least one hand-held fire extinguisher. If you own the aircraft, you probably know whether or not there's an extinguisher on board. If you are renting an unfamiliar aircraft, take the time to determine if a fire extinguisher is installed. Fire extinguishers are often located between the two front seats, but in some aircraft they are squirreled away in a weird location. Even though AC 20-42C recommends that fire extinguishers be mounted where they are readily accessible, I've seen extinguishers mounted underneath the pilot's seat and in locations that are not only inconvenient, they could be downright dangerous in an emergency when every second counts. And if you aren't following a preflight checklist that includes the fire extinguisher and you can't actually see the fire extinguisher, you're likely to forget about it. Out of sight, out of mind.

Once you've found the extinguisher, make sure it is securely held in its mounting bracket. If you are unsure how to remove the extinguisher, the preflight inspection is a good time to get familiar the process rather than during an in-flight fire. If the extinguisher is mounted in a hard-to-reach location, you may decide to remove the extinguisher to complete the next steps.

Check to see what type of extinguisher you have. Halon (halogenated hydrocarbon, a liquified gas) is the most common type for use in aircraft because it can be used on most types of fires, except when the combustible agent is a metal, such as magnesium or titanium. Halon comes in two basic varieties: 1211 and 1301. If you're interested, the four digits represent (in order from left to right) the number of carbon, fluorine, chlorine, and bromine molecules contained in the product. 1211 is a liquid streaming agent that can be projected over a distance and directed at the source of the fire while 1301 is a flooding agent that is designed to smother hard to reach fires. Some extinguishers contain a mixture of these two agents. The main advantage of Halon is that it can reach fires that you might not be able to see, like behind an instrument panel. Halon will also minimize residue left on electronic components, but fire extinguisher damage to a radio stack may be the least of your worries when the cockpit fills with smoke.

If you're worried about the in-flight effects of Halon on you, AC 120-80 advises that Halon discharged in confined spaces may result in dizziness, impaired coordination, and reduced mental sharpness. Since a fire requires a source of ignition, a source of combustible fuel, and oxygen, the goal is to remove the source of ignition, extinguish the fire and then ventilate the cabin. The effects of Halon, if any, should be short-lived if the fire is extinguished quickly and besides, you don't really have many other options.

One issue with Halon is that halogenated hydrocarbons harm the earth's ozone layer and the production or importing of Halon in the US has been prohibited since the Clean Air act went into effect in 1994 (as part of the Montreal Protocol). Though production of Halon is banned, possessing or discharging Halon is not prohibited nor is it against the law to sell a new unit or recharge an existing Halon fire extinguisher. In case you're wondering, discharging a Halon extinguisher just to test it is a really dumb idea: It's bad for the environment and it's expensive, too. In spite of the manufacturing ban, Halon continues to be available because it is recycled from used extinguisher systems. It's been estimated that about 40% of the remaining supply of Halon exists in the US, though the limited supply has certainly driven up the cost. Replacements for Halon will have to be identified eventually.

Virtually all hand-held extinguishers have a safety pin to prevent accidental discharge. Locate the pin and verify that it is in place. The safety pins will usually be held in place by a thin plastic tie that must be broken before the pin can be removed.

If the extinguisher has a pressure gauge, it should be reading in the green. Not all extinguishers have a pressure gauge in spite of the fact that this is the primary way to know if the extinguisher is operable, short of actually pulling the pin and discharging it. If the extinguisher has a service tag, check when it was last serviced and when it is next due for service. If you have removed the fire extinguisher from its bracket, you can also try this test: Note the position of the pressure indication, then turn the extinguisher upside down and right side up five times, then verify that the needle is in the same position. If the needle has moved, have the fire extinguisher serviced.

The standard method for using a fire extinguisher is often summed up with the acronym PASS: Pull the safety pin, Aim the fire extinguisher nozzle or hose at the base of the fire, Squeeze the handle, and Sweep the extinguisher's stream back and forth. This sequence may sound simplistic, but if you start squeezing the handle as you're trying to remove the safety pin, the pin may not come out freely if at all. An in-flight fire behind the instrument panel will make it impossible to accurately aim the extinguisher's stream. Some extinguishers don't have a hose, they just have a nozzle. Many fire extinguishers are marked with instructions saying that you should hold the fire extinguisher upright while discharging or you may reduce the effectiveness.

A Halon extinguisher is well-suited for situations where you can't see the source of the fire. When I used to fly freight, we had a single, large canister Halon extinguisher, equipped with a hose, and mounted between the pilot seats. Since there was no air-tight barrier between the cockpit and the freight area, the procedure for a fire in the freight hold was to 1) don the oxygen mask 2) pull the safety pin on the extinguisher 3) aim the hose back toward the freight area 4) discharge the entire contents of the extinguisher 5) declare an emergency and land as soon as possible. As always, if in doubt, follow the instruction in your aircraft's FAA-approved Flight Manual.

As for how long you have to control an in-flight fire and get on the ground in a GA aircraft, my research only uncovered survivability data for transport category aircraft. In these aircraft there was an average of 17 minutes from the first indication of a fire until the results became fatal. For smaller aircraft, one would assume that even less time would be available.

In the next installment I'll discuss recommendations for handling tripped circuit breakers and the importance of properly dealing with inoperative equipment.

Tuesday, February 17, 2009

Model Behavior


When pilots talk of stick and rudder skills they tend to downplay fancy instruments, instead emphasizing courage and seat-of-the-pants flying skills using the primary flight controls. In fact, I recently heard a claim that the advent of glass cockpit training aircraft is resulting in a new breed of pilots who aren't adept at physically controlling their aircraft. This out-of-hand argument against glass panel aircraft rings hollow to me because the important part of the training equation has always been the pilot and the instructor, not so much the aircraft.

Some instructors tend to emphasize the parts of training they personally find enjoyable or challenging. Precision landings, slips, stalls, pilotage and dead reckoning are just a few examples of possible fixations that can eclipse other important training. It's easy to imagine that some instructors might want to focus on the intricacies of G1000 operations just as it's easy to imagine an instructor spending too much time on power-off approaches to landing. Training fixations can be more directly related to the instructor's biases (or career goals) than to the training aircraft or the student. Professional instructors should strive to provide a well-rounded training experience and that means taking inventory of one's own biases and how they might be affecting the pilots you're training.

Instructors who suffered through the Fundamentals of Instruction remember the Law of Primacy, which states that a student pilot's early experiences will make a strong and memorable impression. A related concept is the Law of Intensity, which posits that vivid experiences are more easily retained and remembered than boring, tedious experiences. Put these two concepts together and it's easy to see why early training tends to shape the way a pilot will fly for the rest of their life, for better or for worse.

I often fly with pilots whose aircraft control is unrefined and this is not because they are incapable of flying smoothly, it is because they were never taught to do so. I believe poor aircraft control can often be traced to a sink-or-swim style of flight instruction: The instructor sits in the right seat and may give directions, offer suggestions, or shout orders, but basically refuses to touch the controls unless the plane and its occupants are in imminent danger. I guess the intent behind this approach is that it will build the student's confidence and self-reliance, but the reality is that there is no single way to successfully teach someone to fly. What the student actually learns in the sink-or-swim environment is pretty much limited by the student's personality, values, and their reaction to the training because a crucial item is missing: The instructor is failing to model desirable piloting behavior and technique, which are two important components of the adult learning process.

I remember taking on a student pilot with a susceptibility to motion sickness. His previous instructor's approach to dealing with this was a seemingly never-ending diet of slow flight, stalls, and even spins. The brute force approach had actually made things worse and this pilot was on the verge of abandoning aviation altogether. We spent many hours in the air and on the ground discussing techniques for dealing with adverse reactions to flight and (gasp!) talking about his feelings and emotions during different aspects of training. A testament to this pilot's determination and courage was that he stuck with aviation, found creative solutions to his roadblocks, and ultimately passed his check ride.

Instructors are pilots, too, and we are not immune to the profound effects of our own initial training: Many instructors teach flying exactly the way they were taught. My own decision to become an instructor was precisely the result of some of the hideous training I endured. Not all the instruction I received was bad, but I felt it was possible to do better. Later, I was fortunate to fly with pilots, many of who weren't even instructors, who had considerably more flight and life experience and who provided excellent examples of airmanship. Learning from other pilots is actually quite easy provided you pay attention, watch what they do, ask questions, and then have a chance to model their behavior. Monkey see, monkey do. It sounds crude, but it can be a very effective way to learn and is a cornerstone of adult learning.

Training aircraft with glass panels are a relatively new phenomenon and many instructors out there learned to fly with steam gauges or maybe in an aircraft that didn't even have any radios at all. Learning new technology can be a challenge for these instructors since they have to overcome their own initial training and (I'm going to be brutally honest here) their own fear of equipment they don't understand. Furthermore, the complexity of these glass panel aircraft requires a more sophisticated and academic approach to training than the old sink-or-swim or monkey-see-monkey-do techniques. Like it or not, we are heading squarely into an age where average, run-of-the-mill aircraft are going to be equipped with GPS, autopilots, and more.

The FAA has long recognized the need for a standardized way to evaluate piloting skill, which is why there is a set of Pratical Test Standards. These standards are used by Designated Pilot Examiners when they administer a practical test for a certificate or rating. No system of standards can cover every eventuality, but the FAA's set work pretty darn well. Some argue (correctly, I think) that the PTS defines a minimum set of standards. An accomplished pilot should eventually be able to perform beyond those standards, whether the aircraft has a glass panel or steam gauges.

Training to proficiency, improving one's skills, and deepening one's mastery of the aircraft doesn't happen overnight, it should be a life-long goal. Instructors play an important role in this on-going process as does continuing education for pilots and instructors alike. Glass panels don't make or break the pilot, but a thorough, proficient, and technologically savvy instructor can.