The pterodactyl, a lizard turned bird that soared on huge leather- skinned wings above the swamps and marshes of prehistoric times, may well have been the first creature to experience IFR flight. Be- cause the earth was frequently covered with clouds of noxious gases from the volcanoes that dotted the landscape, it’s a good bet that the pterodactyls on occasion ignored their VFR-only limitations and flew into IFR conditions. Of course, no one was there to prove it, but quite likely they had an instinctive reaction to counter the sudden loss of visual clues; they were probably able to set their wings for an opti- mum glide speed, maintain direction with some primitive vestibular gyroscope, and keep going until they broke out of the clouds. It’s just as likely that some of them didn’t make it; this theory is supported by the discoveries now and then of pterodactyl remains on or just be- low the summits of mountain peaks.
The blind-flying capabilities of our feathered friends extend to many of the birds we know today — ducks, pigeons, geese, and oth- ers have been known to successfully navigate through the clouds to safety. Humans have not fared so well, requiring some sort of help from artificial references to maintain their spatial orientation. But any- one who has flown Cubs, Airknockers, and the like knows that if things really get bad, they could always close the throttle, roll the trim all the way back, keep the turn needle centered with the rudder, and at least come out of the situation right side up.
When aviation pioneers turned their efforts to making money with airplanes, they soon realized that they would have to figure some way to overcome what appeared to be the insurmountable 29
Chapter Three
problem of flying all the way through clouds — halfway just wouldn’t do. A frightening number of our departed predecessors tried it on guts and confidence, but it all boiled down to the necessity of substi- tuting some kind of instrumentation to replace the natural horizon when it disappeared. Early attempts included “playing it by ear,” lis- tening to the sound of the wind in the ample wires and stays that held those old airplanes together, watching the flutterings of pieces of cloth tied to the struts, and even Mason jars half-filled with oil that were supposed to indicate whether the airplane was banking or in level flight.
None of these early methods worked very well, but with the ad- vent of gyroscopic devices, a whole new world of airplane utility was introduced. When Jimmy Doolittle proved that a pilot could take off, navigate, and land an airplane using no outside visual references, he introduced a method of instrument flight that we use essentially un- changed to this very day.
Whether you took flying lessons yesterday or 30 years ago, one of the first things you learned was that when the curve of the engine cowling, or the top of the instrument panel, or some other reference showed a certain relation to the horizon, and when you had the en- gine wide open, the airplane would climb at a predictable airspeed and vertical speed. You learned that when, at a given airspeed, the airplane was banked until the center post of the windshield formed a particular angle with the horizon, the airplane turned at a certain rate. The substitution of a miniature airplane fastened to the instrument case and moving about a gyro-stabilized bar in the same direction and to the same degree as the actual movement of the real airplane merely transfers to an artificial horizon what you used to see outside. If you set up your old familiar climb attitude with outside references and at the same time notice what you see on the attitude indicator, you can forget the outside clues and rest assured that anytime you put the miniature airplane in the same place, with the same power set- ting, you’re going to get the same old familiar climb performance. That, in a very small nutshell, is attitude instrument flying. It’s basic, reliable, and really very simple to accomplish.
But the attitude indicator can’t do the job alone. Although it’s the heart of the system, you must refer to the other instruments to deter- mine what is happening when you select a pitch attitude that’s 3 de- grees above the horizon, or a 20-degree bank, or a combination of the two. In other words, you must reason to yourself, “I will place this lit- tle flying machine in the attitude that I think will produce a standard- rate climbing turn to the right, and then check the other gauges to see if I was right. If the needles and pointers aren’t moving the way they 30
should, I will change the attitude a bit to get the results I want.” It’s easy to see that, if all the variables are held constant, the same attitude will give the same condition of flight every time. Now, in a manner of speaking, you can set your wings just like the birds and have confi- dence that certain things will take place.