Originally Posted by
PilotJames
My question is, how could we get to a TAS 45kts in a 50 kt headwind?
Assuming ISA conditions surely the IAS would only ever be a minimum of 50 knots just like on the runway.
Once in the air the aeroplane knows nothing about the ground. It it can fly at 45kts airspeed without stalling then it will do so, and it will then appear to move backwards with respect to a ground-based observer just like a boat going upstream at 10kts in a 15kt river current will actually be travelling down-river.
ISA conditions are an irrelevant distraction.
I'm sure this is a simple problem but I think I may be overthinking it!?
Your help would be appreciated.
Yes, you are over-thinking it - picture trying to swim in a fast-flowing river and all will become clear.
BUT
Be very careful about applying this in practice! In a 50kt wind the windspeed 0.001" above the runway is zero. The windspeed 1" above the runway is about 2kts. It doesn't get to the full windspeed until some distance above the ground - this is called the "wind shear effect". If you mess around at 30 feet flying "backwards" in a strong wind you can easily let the height drop a little, and then your airspeed will drop dramatically while the aeroplane accelerates. This has killed many an unwary pilot; it's one of two cases* where wind direction and speed actually affect the handling of the aeroplane. In strong winds stay well clear of the ground until you need to land, and you are then best advised to fly down the approach significantly faster than normal approach speed, leveling and bleading off the excess speed a couple of feet above the ground to negate the risk of falling out of the sky in windshear.
€0.05 supplied,
* the other beeing when doing steeply-banked turns close to the ground in strong winds in an aeroplane with greater tnan typical aspect ratio. This usually means gliders doing thgeir final turn onto a landing heading. Once pointing back into the wind in the very steep bank the wing nearest the ground may be in air with significantly lower wind speed, making it very reluctant to pick up that wing. This has killed a few people and broken a lot of gliders.