Joe Horton wrote: > First off I was just pondering the requirements to get into the "real pilots" lounge....
Sorry about that. That sounded a bit pretentious. I think most folks on this list, and certainly Joe Horton, qualify as real pilots. My point was that just because a guy managed to get a pilot's license, doesn't necessarily mean that he managed to assimilate the differences in IAS, TAS, and GPS speed. I'm not even sure the acronym GPS is even allowed in the standard version of flight instruction. I plowed through my FAA written exam by buying a Gleim manual and cramming for three straight nights, and taking the test on the fourth day. It's not that I'm a procrastinator, but I got wind of the written test being given four days later, and I only had that much time to study. I made a 98 on it, and the only question I missed was the most obvious...something like "the AWOS is reporting wind at 195 degrees, so do you take off on runway 180 or 360?" I'll chalk that one up to checking the wrong box. But my point is that I managed to get all the way through flight training in a C-172 and the subject of TAS vs IAS never came up. So during first flights I too wondered why the airspeed indicator was reading slow at higher altitudes. I was not a "real pilot" yet, and had (still have) a lot more to learn. Anybody that's flown with me knows that I still have a problem figuring out the runways when I arrive at a new airport, although I now have a lot more information at my fingertips while airborne, and make a point of studying the runways while planning a flight. Another point on IAS is that if your ASI is off on the low end, there's often nothing that can be done about it. Mechanical gauges in particular likely have that limitation, and even the iEFIS in my plane lacks enough calibration points to deal with the low end adequately. I'd venture to say that most airplanes are off by 5% or more on the low end of the ASI scale. Mine's off way more than that. Cosine error of the pitot tube's angle of attack could account for 3.5% of it at stall. OK, I'm back to brakes, wheels, and tires... Mark Langford ML at N56ML.com http://www.n56ml.com
