A question for Jetstar drivers into Avalon

[Buster Hyman]

I'm trying to find out if there is a name or term used by Jetstar crew (or anyone else for that matter) when they are at a particular point in their approach to Avalon.

The location would be roughly parallel to the northen tip of Tulla as it passes below on your right. It seems that there is a reduction in engine power & that is accompanied by a unique sound as this happens.

I'm also curious as to your rough altitude at this point too.

Cheers :ok:

[metrosmoker]

Yes.
Its called Melbourne airport. You get descent to 6000ft until you are clear of the traffic pattern. Then you get descent to 3000ft for the ILS. The reduction in engine power is probably just that, guys use the level off to slow down instead. There shouldn`t be much of a noise reduction as you should be at or close to flight idle during the descent. As for the other unique sounds, that is a company secret and I can `t discuss it here. But lets just say, REG lives near by.

[Mustangbaz]

maybe spoilers?

[Buster Hyman]

Thanks metro. I'm doing a risk assessment for my CFA Brigade & wasn't sure what height you passed over us at. The noise bit was out of curiosity. :ok:

Thanks Baz. It's definitely an engine type noise I hear, sort of like when machinery powers down however, as my qualifications fall a little short on the "engine-y type noise" identification, I'll accept any hypothesis! :ok:

[uncle8]

I live NE of YMML under the approach for RWY16 where jets inbound to Melbourne are at 5000-8000ft. The A320s often, not always, have this distinctive noise which comes from the speed brakes/spoilers, I think.
Seems to be more prevalent with Tiger.

[Buster Hyman]

Well, that is interesting uncle8. You & Baz have the same thoughts on that sound. I would never have imagined it to be spoilers/speed brakes but, you're never too old to learn.

Cheers. :ok:

[Keg]

It might be the first stage of flap being selected and changing the airflow sound.

[Chief galah]

Same thing happens on the WAREN-MONTY track about 20nm out, always with A320's. More aerodynamic than mechanical in sound.

[Buster Hyman]

I'd record it for you all, but I don't think the microphone will reach...

;)

[Kiwiconehead]

I'm in Sydenham and hear the JetStar DeathStars go over all the time, sounds areodynamic, after many years around the Mighty Dozer of the Sky, the BAe146, it does bring back disturbing memories.

[training wheels]

I'd record it for you all, but I don't think the microphone will reach...

;)

Can you use a laptop? I'm quite curious as to what this sound could be.

[Its the Pleats]

The unusual sound you hear sometimes from A/C overhead - especially A320s - is the speed brakes being RETRACTED... apparently!

[ozblackbox]

Man.... I was going to post about that sound about 2 years ago when we moved to Melbourne Eastern suburns. Thought that if I posted that I would be sent to the looney bin.

We live under the WAREN STAR and we get this sound numerous times a day and only from the A320... be it Jetstar, Tiger or Air New Zealand.

Even my 3 year old son runs outside when he hears this sound and tells me to run outside quickly as "Jepstar" are flying over.

I have been paying attention over the last few weeks and it seems to only be when they are on a high speed descent - this made me think that it must be aerodynamic. I'm pretty certain that it's not an engine spooling down during a high speed descent to slow the aircraft down to 250KIAS.

I'll try and have my mobile ready to record it the next time it happens - just difficult to catch as the sound comes and goes quite quickly.

[ARFOR]

If it is the same sound I am thinking of, it will make you look-up because it sounds like it is coming towards you. Sort of like air rushing in a window only just cracked open, but it starts off with a low grumble and quickly rises in tone then disappears. Bit like a suction type sound :confused: hmmm, struggling to describe it better than that.

Wing geometry, flaps, spoilers ,device movement to/from the stowed pos?

Only ever hear it from the A320's

I fondly remember years ago, watching [from under shortish final] 727's and 9's landing. If the conditions were right, the aircraft would scream over head, only to be followed some 10 - 15 seconds later by a ripping air whoosh sound of the wing tip votices running outa puff. The 727 was the most pronounced. I always think of those sights and sounds whenever thinking about wake turbulence.

[Buster Hyman]

Don't forget the crackle they made on take off ARFOR! Ahh, memories & ear aches! :ok:

[Keg]

It appears that we're all describing a similar sound although I've heard it from other aircraft types- including most Boeing types. Last time I heard it the a/c was over flying at 6000' on a cross wind from the pacific to land on 34L at Sydney.

(How do I know it was 6000? Because that's the altitude I've always been at as I crossed over my place when flying that particular approach). :ok:

[PyroTek]

Though I have not heard the noise, but from ARFOR's description, could it possibly be the sound of the air just making it in between the gaps between the flaps and the spoilers? Or possibly between the leading edge flaps and the leading edge of the wing? - just like opening a window :ok:

[ARFOR]

:ok: Owen, indeed :)

Buster too right mate. Those early LB JT8D Pratt's were the real deal :D

I miss seeing and hearing those beautiful machines [727] :( Best looking Boeing ever made IMHO

If the truth be known, this is my desktop wallpaper B727 N800AK DALLAH AL BARAKA on Flickr - Photo Sharing! (http://www.flickr.com/photos/shanair/4036618255/)

A RR Tay powered Super27 beauuuuuuuuutiful :ok:

Pyro I reckon it must be to do with a certain configuration of wing devices. Last few A320's I have heard make that sound have been at around 10-15NM to run to touchdown

[PyroTek]

Now getting even more .. scientific... Could possibly be a mix of the wing flaps extended and spoilers extending. - the gap between them increases, creating a vacuum of sorts, thus airflow in between the trailing edge flaps and the spoilers is momentarily increased - to equalise pressure? Or am I going too in depth? - could only happen on the A320 (and similar types) because of how the flaps/spoilers are configured?

[Buster Hyman]

PyroTek...you're lucky this isn't JetBlast! They'd run you outta town for a technical answer like that! :ok:

In all seriousness, it's fascinating to read the theories here. I really thought I had it sussed & would never have considered it an airflow sound. :ooh: I'm really going to have to record the noise now...better check those schedules!

[ARFOR]

It will be interesting to hear, if you can catch it. :ok:

[BULLDOG 248]

About 2 years ago I stayed at a nice little B+B about 15nm from Gatwick Airport in the UK. Heard the same sound many times through the day on Airbus and 737 types. The B+B was owned by a retired airline pilot and saw me looking up at this noise and asked if I knew what it was??? Having never flown a jet, I said I had no idea???? But guessed maybe flap selection???He said it was at the point on fast approaches where the engines were reduced to idle and was an engine/fan/air noise??? I just took that as gospel and believed him.
Reading these posts I'm now not convinced.
Am I right in saying the wooshing sound seemed to stop quite quickly.

[ozblackbox]

Don't mention the B727.... it's like mentioning the war! Last flew the beautiful old gal in 2006 on the AAE contract.

I'll ask a few of my A320 driver compadres. They may not even know as it's nice and quiet up front.

The sound is like a loud howling sound that decreases in pitch as the aircraft approaches (I'm sure it's on high speed descents >250Kts) and then suddenly it's gone.

I'm actually slowly tending to change my opinion to it being engine fan noise as BULLDOG 248 mentioned.

[Buster Hyman]

The AN A320's with the CFM's had that God awful buzz that reverberated through the cabin Oz...not as quiet as the V powered ones.

In general, I've never heard anything more excruciating than the old TE DC8F's. Fair dinkum, I was poking my ear that hard I swear I felt my other finger!!! http://illiweb.com/fa/i/smiles/affraid.gif

[boofta]

When the flaps whatever, are running the exhaust from the demand
hydraulic pumps goes overboard. Thats the noise your all hearing!