Insights

Are You Using All Of Your Senses?

I will give away my entire aviation library before I'll part with my copy of Stick and Rudder, Wolfgang Langewiesche's (Long-gah-vee-shay) timeless book about flying airplanes that was first published in 1944.

Chapter four, "The Flying Instinct," explains how you sense what Langewiesche's calls buoyancy. He states, "For this is perhaps the most hard-to-get-at skill in the whole art of flying - the sensing of 'lift,' the gauging of the firmness of one's sustentation, the 'feel' a pilot must have for his ship's angle of attack, the ability to know how close the ship is to the stalled condition: This is what pilots used to call the flying instinct."

Modern flight training with its emphasis on integrated instruction and instrument reference often ignores the factors that Langewiesche discusses - factors that are not inconsequential. They are critical for competent airmanship. Ignoring them explains why we continue to see stall/spin accidents and why flight training may be increasingly difficult and frustrating for many student pilots.

The proper use of your physical senses is the concern, and hearing is the first consideration. Airflow noise past doors or windows and through air vents is a direct indication of airspeed. Engine noise is a direct indication of engine power. Using a modern headset diminishes these sensory inputs, particularly if it is a noise-attenuating headset. Still, like most pilots I prefer the advantages that today's headsets and boom microphones provide compared to cockpit speakers and handheld mics. And even though external sounds are muted by headsets, I can still hear clues that tell me what the airplane and the engine are doing.

Students will tell me they prefer one airplane over another identical model because the two airplanes "fly differently." I ask if they use the same descent power settings in both airplanes when landing, and the answer is always yes.

If I set 1,400 rpm in both of those airplanes for descent power, I will likely note that the engine noise is not the same. Engine power differs even though both tachometers read 1,400 rpm, and this would certainly cause students to think that one airplane flew differently than another. Small power changes produce noticeable performance changes, and tachometers are not that accurate.

Control feel is an indirect indication of airspeed. As airspeed decreases, control resistance decreases; as airspeed increases, control resistance increases. Rudder and elevator feel can be misleading because they are influenced by the propeller slipstream when power is applied, but that is not the case for aileron feel. Control position is an indirect indication of angle of attack. If the yoke is well aft, the angle of attack is larger than it would be when the yoke is well forward at the same power setting. Control response is an indirect indication of controllability. Making slight, momentary control inputs when flying at approach speeds yields important information. If attitude response is positive, you have an airspeed safety margin. If attitude response to control inputs is sluggish, the safety margin is minimal.

At the end of the chapter, Langewiesche asks two questions: "But what about the airspeed indicator? Can't you always tell by the airspeed indicator how far you are from the stall, how much buoyancy you have?"

He goes on to answer his own questions. "The answer is neither a straight yes nor an outright no. The airspeed indicator is indeed the pilot's most important flight instrument. As our airplanes are now equipped, it is the only instrument that indicates anything at all concerning buoyancy, angle of attack, closeness to the stall. But it is not a simple and straightforward instrument. In the first place, it can develop mechanical trouble. In the second place, it has some peculiarities that must be understood before it can be used as a buoyancy meter or a stall-warning device. Ignorance of its peculiarities has cost many a pilot his life."

Fly safe and stay safe by learning to use your physical senses to back up the airspeed indicator.