View Full Version : HWC/TWC in Pattern
Speedwinner
5th Dec 2021, 08:31
Guys,
some quick formula how to calculate the TWC/HWC in the pattern in a A320?
Thanks so much
If it is any help, for a Cessna 150 the headwind component is (Cosine of the angle of the wind off your heading) x (the wind speed).
eg 45 degrees off = .7 x wind speed: 90 off = 0: on the nose = wind speed.
I'm sure you can adapt that to an A320?
dixi188
5th Dec 2021, 17:15
Used to have a nice little chart on a clipboard, but I don't suppose you use clipboards these days.
Vessbot
5th Dec 2021, 17:23
Pay attention, he asked for the Airbus version. You don't need a clipboard when the airplane is equipped with a tray!
dixi188
5th Dec 2021, 19:19
Sorry, my clipboard was for a Mk1 Airbus and I had a table facing sideways.:)
If it is any help, for a Cessna 150 the headwind component is (Cosine of the angle of the wind off your heading) x (the wind speed).
eg 45 degrees off = .7 x wind speed: 90 off = 0: on the nose = wind speed.
I'm sure you can adapt that to an A320?
The funny thing is, the math doesn't change and the airplane doesn't care. Cosine of the wind angle x wind speed works every time, no adaptation necessary. The only difference is that in something like a 320, you've got much less time to figure it out than a single-engine Cessna. Operationally, you've got to find a quicker way to figure it all out that is not formula-based - you don't have time to plug in the variables doing 200 to 250 knots. So, use the cosine method described above, and even if you just remember a few of the values as a function of speed you're fine. I've committed every 20 degrees to memory and then add or take off a bit as necessary. It works well enough:
5-degree crosswind equals 99% of the wind speed
25-degree crosswind equals 90% of the wind speed
45-degree crosswind equals 70% of the wind speed
65-degree crosswind equals 44% of the wind speed
85-degree crosswind equals 87% of the wind speed