Unusual noise after a plane lands

Grandeeod · 10-01-2013 05:48PM #1

Hi folks.

Quick question. I live in the Canary Islands. Planes pass over my house at about 500 ft on approach. After they have passed over there is a funny kind of noise in the air like a wind of some sort. Can any of you explain it. Cheers.

H3llR4iser · 10-01-2013 05:54PM

First thing coming to mind is reverse thrust ...essentially, after and airliner touches down the pilot(s) can deploy a device that redirects the engines air jet forward, helping the wheel brakes slow the aircraft down.

In order to slow down more efficiently, the engines spool up a bit when the reverse thrust is applied - this, combined with the mechanical device that redirects the airflow, produces sort of a "whoooosh" sound that's probably the one you hear

phonypony · 10-01-2013 06:00PM

Could it be you are hearing the wake vortex created by the aircraft's wings? It basically leaves turbulent air behind which descends to the ground, it has a sort of whirring/whistling sound.

smurfjed · 10-01-2013 06:02PM

One of the effects of a wing generating lift, is circular wind patterns behind the wing, they are called wingtip vortices. They sound cool, but are dangerous to the following aircraft. Google the term and you will find some pretty cool pictures of the cloud or smoke showing the effect.

smurfjed

debabyjesus · 10-01-2013 06:04PM

phonypony wrote: »

Could it be you are hearing the wake vortex created by the aircraft's wings? It basically leaves turbulent air behind which descends to the ground, it has a sort of whirring/whistling sound.

Its the wake alright. More noticeable with bigger aircraft. Its just air turbulence

Grandeeod · 10-01-2013 06:06PM

Its definetly a whooshing/whipping sound in the air about 20 secs after the aircraft has passed over.

Grandeeod · 10-01-2013 06:23PM

Just looked and listened to the wake vortex on youtube. Thats the sound alright. Thanks for the help folks.

bluecode · 10-01-2013 07:41PM

Yes the wake vortices. A whipping and cracking sound. Rather spooky at times.You must live pretty close to the airport.

A few years ago my wife and I booked a short holiday in Rhodes, really cheap. On the brochure there was a small innocuous comment: 'May be aircraft noise'. They weren't kidding. As I stepped off the coach. I looked up to see a 757 heading directly towards us. When I got to our room, I stepped onto the balcony noting the view was a familiar one. Essentially finals to the runway but a little low. The PAPIs were red. When the jets flew over the sound of the vortices hitting the roof was incredible. They weren't too many flights during the day. No they tended to arrive early in the morning, very very early.:eek:

But oddly enough we soon got used to it and would sleep through it. Which was more than can be said for the damm cockerel in a farm nearby. If I only had a gun!

Lying by the pool during the day was great fun. If you were a plane spotter you were in heaven.

JD93 · 10-01-2013 08:04PM

Yeah Ive heard that noise when I was working last summer in Club La Costa in Tenegrief. Like a swooching noise after big planes like 767s came gliding in.
A guest did tell me its waked turbulences made by the wing and slow speed of the plane before landing.
He said that small planes had to wait 3 minutes before being in the same place in the sky??

The resort is so close to the runway you can feel the power taking off and when they hit the reverse after touchdown. I dunno how the golfers felt!!
Last summer daydreaming and watching the planes got me hooked.

Grandeeod · 10-01-2013 08:20PM

JD93 wrote: »

Yeah Ive heard that noise when I was working last summer in Club La Costa in Tenegrief. Like a swooching noise after big planes like 767s came gliding in.
A guest did tell me its waked turbulences made by the wing and slow speed of the plane before landing.
He said that small planes had to wait 3 minutes before being in the same place in the sky??

The resort is so close to the runway you can feel the power taking off and when they hit the reverse after touchdown. I dunno how the golfers felt!!
Last summer daydreaming and watching the planes got me hooked.

You were near me so. I'm on the Golf near Aerpeurto Sur. Had to finally ask the question after too many visitors asking me!

LeftBase · 10-01-2013 11:47PM

The front rugby pitch at ALSAA is a famous location for kickers to have their kicks messed about by the tip vortices of the aircraft passing overhead landing in Dublin.

arctan · 11-01-2013 01:25AM

while on the topic ..... under the flightpath for dublin and numerous times I've heard planes "woosh" out of knowhere

usually you get a gradual build up of noise, but on cloudy nights, you hear a sort of "fffeeerrrrrnnnnnnnnn" then the normal jet noise as it goes overhead then

what is this ?

seven_eleven · 11-01-2013 01:22PM

https://www.youtube.com/watch?v=xaPZeDQ4pyQ

H3llR4iser · 11-01-2013 01:26PM

Are you sure the sound isn't like this, OP?

http://www.youtube.com/watch?v=sqSFGVL6XhA#t=0m45s

(ehm, not the cows!)

I'm not saying that what the others propose is wrong - quite the contrary. The wake turbulence is a very likely candidate and I simply didn't think about it in the first place. It's just that I feel like asking because I have a very similar memory from my childhood; Essentially where I lived (Naples) there was and still is a shopping centre directly underneath the descent path to the runway. I would bug my parents to go there on a Sunday just to stand in the car park and watch all the civilian and military jets land; With civilian airliners, after they disappeared behind the motorway bridge that obstructed the visual to the runway, you'd clearly hear the engines spooling back up as they engaged reverse thrust.

Of course we're talking mid '80s here, the planes were mostly DC-8s, DC-9s and 737 Jurassics with much noisier engines than current liners.

phonypony · 11-01-2013 01:46PM

arctan wrote: »

while on the topic ..... under the flightpath for dublin and numerous times I've heard planes "woosh" out of knowhere

usually you get a gradual build up of noise, but on cloudy nights, you hear a sort of "fffeeerrrrrnnnnnnnnn" then the normal jet noise as it goes overhead then

what is this ?

I may be wrong but I think this is a doppler effect created by the position of the aircraft relative to the listener, similar to the changes in pitch you would hear as an ambulance siren moves towards and then away from you. The engine pitch of the aircraft seems to surge and then lessen.

Just an edit to add that cloud (moisture) can do odd things to sound too, including changing the speed at which it travels and the frequencies absorbed/reflected. Often you wouldn't hear an outdoor gig from a few miles away on a clear night, but with cloud it can be pretty loud.

The Idyl Race · 14-01-2013 12:43AM

Grandeeod wrote: »

Hi folks.

Quick question. I live in the Canary Islands. Planes pass over my house at about 500 ft on approach. After they have passed over there is a funny kind of noise in the air like a wind of some sort. Can any of you explain it. Cheers.

Did you break wind and blame it on the dog, who was upstairs at the time? Shame on you.

Unusual noise after a plane lands

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