The problem with winter, combined with the lack of a night rating, is that I either have to go flying on an extended lunch hour or on the weekend. Since I work 20 minutes from the airport but live an hour from the airport, weekend flying doesn’t happen very often. So lunchtime it is. But that means that I can’t fly for very long or I’d be gone half the day. Which in turn means I can’t fly very far, so the flights start becoming a bit repetitive.
One way to alleviate the boredom is to do some experimentation, so on today’s flight I did just that. We all (are supposed to) know how to compute actual winds aloft from ground speed, track, airspeed, and heading. And we all learned how to compute our ground speed and track by plotting our progress on a map. If you have a GPS of course, you can read ground speed and track directly off the display.
But if you have a GPS, there’s an easier way to measure the winds aloft. All it takes is two minutes, one subtraction, and a division by two. Here’s how:
- First, set your GPS to a page that simultaneously displays ground speed and track.
- Fly a constant-airspeed rate-one turn (180 degrees per minute) while checking the ground speed and track every few seconds. Watch for traffic!
- Make a note, on paper or in your head, of both the fastest and slowest ground speed you achieved during the turn, and what the track was at those times.
The difference between your fastest and slowest ground speed, divided by two, is the wind speed. The direction you were going the slowest is the wind direction (the direction the wind is coming from). As a sanity check, the direction you were going the fastest should be the reciprocal heading of the slowest direction.
Not rocket science, but useful nonetheless.
Date: 2007-Feb-23
Aircraft: C-GCVY, DA20-A1
Passenger: None
Route: CYKF - CYKF
Flight Time: 1.1h
Takeoffs and Landings: 1
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