Even without having ever been in a functional airplane, Leonardo Da Vinci observed, For once you have tasted flight you will walk the earth with your eyes turned skyward, for there you have been and there you will long to return.
Flying in a small airplane, whether as the pilot or as a passenger, is an experience worlds apart from anything else in human existence. Da Vinci’s incomparable imagination made an attempt to appreciate what one could see, feel, and do in the skies, but even his incomparable imagination was circumscribed by a lack of aerodynamics, meteorology, and, yes, even mechanical engineering knowledge. Despite all that, he was spot on about how even one such flight grabs you and keeps you looking upward.
In this discussion we will consider small planes, (often called “private planes” or “light planes”), as the typical four-seat, single-engine airplane that most people use when they are learning to fly. In fact, these small miracles of engineering give all of us an even better, more interesting experience than the larger, clunkier, heavier aircraft that tend to be used more in commercial aviation.
You may be surprised to know that some of these very special, aviation-related experiences are pleasant but others may be considered unpleasant.
Visual Experiences and Optical Illusions
Perhaps the majority of special experiences fall into the visual realm. Some of these are just unusual things one may see, but others are optical illusions that occur only in aviation. A considerable part of training for pilots tells them about these optical illusions and gives them experiences with them so that, when they are encountered, the pilot is on top of things and not fooled.
The Zoo at the Airport
As noted in other CalAero blogs, the pilot and passengers may see animal surprises like rabbits scurry across the runway while an airplane is taking off or even landing. By the way, those critters almost always make it across, but it does tend to startle passengers who have the privilege of seeing out the front window.
Finding an airport at night
If you have the chance to go for a night flight with a night-current pilot, check this out: in urban areas that have lots of illumination, a pilot will often see a long, large dark spot in the ground. That’s because the runway and taxiway area of an airport will not have a lot of illumination. So to find an airport in an urban area, look for where there does not seem to be anything.
Where are We Landing?
While passengers typically assume that the airplane lines up with the runway as it descends for a landing, there are many sets of conditions where the pilot must point the nose of the airplane away from the runway. What’s really happening is that the pilot is adjusting for a crosswind, which is wind that is not blowing right down the runway. This can look confusing for a passenger unless he or she (or you) understand this technique.
Hey, look at all those swimming pools!
It is so common as to be predictable that when a first-time passenger is taking off in a small plane, and if the flight is in a predominantly urban area, the passenger will be very surprised at how many people have swimming pools! Driving by houses doesn’t really tell you what’s behind them, but when flying over them, very little can be hidden unless it’s under the roof of the house.
There’s a truly-funny scene in the movie, Rat Race, where a jealous helicopter pilot flies over her boyfriend’s house and spies him with another woman in the backyard. It provides an unanticipated, pretty wild ride for the passenger in the aircraft.
To the Mountaintop
For example, when approaching a mountain crest, particularly in dusk conditions, it will very often look like you are too low: like you are about to fly right into the side of the mountain. As you get closer, the mountain crest appears to descend, so you can see that you are at an altitude where it is completely safe to cross that mountain crest. Pilots know the proper altitudes because they have aeronautical charts that show them high spots and different altitudes, so you don’t really need to worry about it. Enjoy the show.
The False Horizon
A “cloud deck” is an extremely-wide layer of clouds. Sometimes these decks can extend as far as the eye can see. People who are stuck living on the ground usually don’t even realize this happens, but cloud decks are very often not horizontal. Many of them sloped upward or downward or off to the side, depending on the direction you are flying. Non-pilots are used to the horizon being more or less level. A pilot must ignore this illusion and use his or her instruments to identify where the actual horizon is. Otherwise, you might end up climbing or descending or tilting in a direction or you thought you were flying straight and level.
When an airplane first penetrates fog (goes into a cloud) it will often seem like the airplane is beginning a fast climb, with the nose pitching upward. That is not what’s really happening, but it is an overwhelming illusion until you’re used to it. Again, the pilot knows about this and does not react inappropriately.
The Inversion Illusion
When an airplane is climbing and changes immediately to straight and level flight, so the climb has now been completed, it can feel like the airplane is tumbling backward. This is because of the way the inner ear operates, and the illusion is virtually unavoidable. Thank heaven for pilot training!
Runway Visual Illusions
If you are standing on an airport or park near it and watch airplanes come into land, it will seem to you like they all landed more or less on the same spot on the runway and that it’s a simple thing to do this. Well, there are multiple illusions that can make runways look different to a pilot, and he or she must take that into consideration to do proper landings. For example, if a pilot is used to landing on the runway of a certain width, say 150 feet wide, and then comes into land on a very wide runway, say, 500 feet wide, it will appear to the pilot that the airplane is much too low. There are many illusions of this type, but, fortunately, pilots are trained to be aware of them and handle them. This is one where the passenger probably would not be aware of any difficulty or illusion since the passenger has not had visual training, but these illusions can affect unwary pilots.
Somatosensory (Feeling-Related) Experiences in Aviation
So far, we’ve considered mostly-visual phenomena. Another interesting level of uniqueness in aviation involves the sensors other than the eyes: The body’s ability to sense motion, for example.
Winds ‘R’ Us
Unlike being held in an extremely large metal tube such as an airliner, when you are flying or a passenger in a small plane, you are much more in touch with nature. That means that if there are small winds, you get to feel being blown in whatever direction the winds are going. So bumpiness and other forces that move the airplane a little, rather than being scary or uncomfortable, should be fascinating. After all, you’re now hand-in-hand with nature rather than fighting it.
Why Did it Get Bumpy Just Before We Landed?
Winds interact with structures, whether “natural” (like mountains or lakes) or manufactured (like hangars, offices, and other structures not too far from the runway). The best way to understand this is that air “splashes” onto structures just as water would. Pilots are aware of this and may make changes to their approaches to counteract adverse winds near the runways.
Penetrating Temperature inversions
Particularly interesting is flying into or out of a temperature inversion. If you are descending from a high-altitude into a temperature inversion, what you’ll notice is that the temperature gets slightly warmer as you descend, and then, when you hit the inversion (which is often very visibly obvious since you were flying in clear air and all of a sudden you hit smoke or smog or basically junkie air), all of a sudden the temperature shoots up 10 or 15°. It is an amazing an obvious change in temperature. Then as you continue to descend pass the actual inversion, the temperature will go down again. It’s a fascinating way to experience weather phenomena very first-hand.
Tip of the Aeronautical Iceberg
There are literally hundreds of possible illusions and other phenomena that can affect flights, in some cases simply making them more interesting and in others making them more technically-challenging.
You may wish to talk with a pilot about these; most have interesting stories of their experiences with illusions. You may wish to do a YouTube search for Aviation Visual Illusions to see and learn about some of these.
Mr. Matthew A. Johnston has over 23 years of experience serving various roles in education and is currently serving as the President of California Aeronautical University. He maintains memberships and is a supporting participant with several aviation promoting and advocacy associations including University Aviation Association (UAA), Regional Airline Association (RAA), AOPA, NBAA, and EAA with the Young Eagles program. He is proud of his collaboration with airlines, aviation businesses and individual aviation professionals who are working with him to develop California Aeronautical University as a leader in educating aviation professionals.