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# HWC/TWC in Pattern

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# HWC/TWC in Pattern

5th Dec 2021, 09:31

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HWC/TWC in Pattern

Guys,

some quick formula how to calculate the TWC/HWC in the pattern in a A320?

Thanks so much
5th Dec 2021, 13:37

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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?
5th Dec 2021, 18:15

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Used to have a nice little chart on a clipboard, but I don't suppose you use clipboards these days.
5th Dec 2021, 18:23

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Pay attention, he asked for the Airbus version. You don't need a clipboard when the airplane is equipped with a tray!
5th Dec 2021, 20:19

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Sorry, my clipboard was for a Mk1 Airbus and I had a table facing sideways.
9th Dec 2021, 17:20

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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

Last edited by +TSRA; 9th Dec 2021 at 17:20. Reason: Removed a spurious bullet point
10th Dec 2021, 17:56

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Ah, never mind.

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