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<< Greg Nelson wrote: Am I Wrong? Unless I am landing or taking off under extreme conditions (such as hot,
humid, heavy,  SNIP
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Greg, you did put most of the right caveats on your use of groundspeed as a flight/performance reference. Groundspeed is needed to compute how long it will take you from A to B, and indirectly how much fuel you will consume in the process, but is not a valid measurement for any flight performance characteristics about your airplane. Further, GPS groundspeed typically lags the actual groundspeed when changing flight conditions due to the lag/buffers intentionally built in the GPS computer. Admittedly, groundspeed approximates the performance-driving airspeed values closely enough in most cases to be used, but as I have personally observed, the "other 2% can kill you." and more often than that mess up a perfectly good Lancair. I presume your comments about these old terms were made at least partly in jest, but their basis is valid and grounded (pun intended) in hard-learned lessons. While groundspeed is probably the best in-flight/cruise reference for at least part of your planning/use, consider using an airspeed reference for all other flight operations.

Bob Pastusek

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