I have actually never met anyone that put McCready value of over 3.5 on their computer. Many summer days in the west, you will have your choice of 5 to 17 knot thermals, never taking anything less than 7 knots. The pilots I have compared notes with even while flying in these conditions rarely if ever put in a McCready of over 3 perhaps 3.5.

So I am asking in practical terms. Yes, i now about McCready theory, but do not know anyone that follows it moe than a very rough guideline. So back to the original question...


On Friday, February 12, 2016 at 1:56:00 PM UTC-8, Alex wrote:
The idea of speed to fly indicators is to show you the speed to fly. That counts in sinking air as much as it does in rising air - the theory remains valid also for rising air. By principle it does not make sense to fly slower than you stf indicator tells you. The only exception is of course if the lift is higher than you MC-setting in which case you must thermal. In situations where the STF indicator tells you to thermal it can be an option to slow down in straight flight flight or s-turning instead of flying circles.. I sometimes do this if I don't want to thermal even if it makes sense theoretically - for example if I am close to cloud base or under a cloud street where I can get to cloud base without circles.

On my first flights with a fully ballasted ASG29 it took some getting used to that best glide is at almost 130km/h and it makes not sense to slow down to 95km/h whenever there is a bit of lift.