Tuesday, July 5, 2011
When we’re our own worst enemy
Aviation is loaded with stories about the adventures of airline pilots learning to fly small airplanes, but this is doing airline pilots a disservice. The exact same problems exist for anyone used to flying heavier, larger airplanes, when learning to fly much smaller airplanes. And vice versa. Think about it: You've spent 20,000 hours in cockpits that are 30 feet off the ground, so letting a runway come up to within 10 feet or so of eye level is bound to spark some primordial survival response. The little voice in your brain is going to be squalling, "Pull up! Pull up!"
The reverse is also true: Regardless of what we see in adventure movies, a Cessna pilot in the left seat of a 747 in place of the sick pilot (why do they ALWAYS eat the fish rather than the chicken?) will most likely drive it into the runway. He'll flare too late because that's the way he's used to seeing it: Cessnas aren't meant to be landed at 40 feet.
Examples like the above show that the eye-hand coordination thing is very real, and our eyes are subject to "memory" just as much as our muscles are. We get used to things looking a particular way at a particular time, e.g., during flare, making turns, etc. The visual signals go into our mental processor and come out through our hands in the form of muscle memories, and we wind up having to retrain our eyes as much as we do our hands.
Takeoff Timing And Density Altitude
Throughout aviation's history, muscle memory has played a diabolical role in any number of density-altitude takeoff accidents. Even though pilots know they should wait until the airplane is indicating a proper speed before attempting to lift off, they don't realize how much timing and muscle memory control their reactions until they're faced with a serious high-density altitude challenge. Even when forewarned, they'll often make the same mistakes.
It's not unusual when taking off at high altitude for flatland pilots to line their ever-faithful 172 up on the runway, see 4,000 feet of pavement in front of them, and breathe a sigh of relief. With that much runway, they aren't worried that they're right at gross, or that the OAT may be bumping 100 degrees, and they're at 5,500 feet MSL. On top of that, they didn't lean to peak rpm. A chain of errors borne of a form of muscle memory: This is the way that they've always done it, and they don't recognize that this is a different ball game. Call it mental muscle memory.
Airline pilots who transition to smaller airplanes will be faced with muscle-memory problems, and during landings will tend to flare much higher than they should. Likewise, Cub pilots who move into a much larger airplane will flare too late because they're responding to the sight picture that they're used to.
In these kinds of situations, pilots are letting their habits and muscle memories, which were built up from many prior flat-country takeoffs, overcome what they were told in ground school about these kinds of situations. Intellectually, they know that if it doesn't have the proper indicated airspeed, it's not going to fly. However, they've rolled so much farther than they've ever seen an airplane roll before that they just can't believe that it's not ready to fly. But, it's not, and the results are often tragic.
In the foregoing paragraphs, we've dealt with a rather narrow series of situations, but there are actually lots of scenarios where muscle memory can bite us in the butt. The key to rehabilitating those muscles and making them fit any new situation is to recognize exactly what it is that this particular airplane and this particular situation demand of us. More important, we have to recognize that what we've done in the past may or may not work in this new situation.We don't want old habits to breed new problems.
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