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Passing planes and other whoosh sounds

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207 points zdw | 2 comments | 17 Apr 25 05:53 UTC | HN request time: 0.46s | source
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roygbiv2 ◴[17 Apr 25 08:36 UTC] No.43714351[source]▶
We have planes pass overhead at about 6000ft. When the conditions are right they'll make a completely different sound, I've always assumed it's the Doppler effect mixed with the valley we live in but I'm always very curious when it does happen.

They make their usual sound but then there's a second sound that arrives, a lot higher pitched. Sounds like they've struck it in reverse or something (they haven't they're just doing a normal decent).

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1. oe ◴[17 Apr 25 09:51 UTC] No.43714747[source]▶
I think it’s some engine type that makes the sound at some specific speed / throttle setting. But I can’t remember the specifics. Some planes passing us make the sound, most don’t.
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2. LargoLasskhyfv ◴[17 Apr 25 23:24 UTC] No.43723313[source]▶
Could also be FOPPs, or both combined! (Fuel Overpressure Protection) https://aviation.stackexchange.com/questions/23701/what-caus...

Some do it at certain airspeeds, others don't. Depends on their shape, and can be mitigated/eliminated, which is sometimes done, other times none.