DUSint
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737-200 "horn" Sound

Tue Jun 04, 2013 9:02 pm

On my flight with the Aviogenex 732adv there was a very distincitve sound to be heard on final.
You can notice it here at seconds 00:16, 00:36 and very clear at 00:47.
http://www.youtube.com/watch?v=zvSwy7bqdaE
It was quite loud and resembled the horn of a train in a funny way.
Is this sound common on the 732? Can someone please identify the source of it?
Thanks!

Other than that the flight was very pleasing, it was my first one on a 732.
There might have been some in my childhood but I can't remember...
I always imagined the JT8Ds would be much louder in the cabin (like in the DC9/MD80) - actually to me they seemed even less noisy than the CFMs, at least while taxiing. The engine start up was hardly noticeable at all.
 
stratosphere
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RE: 737-200 "horn" Sound

Wed Jun 05, 2013 10:01 pm

I have flown on 737's and have never heard that before. It could be that carriers alert to flight attendants but usually it is a chime. Maybe someone else on here can shed a better light on it.
 
BoeingGuy
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RE: 737-200 "horn" Sound

Thu Jun 06, 2013 12:06 am

Quoting stratosphere (Reply 1):
I have flown on 737's and have never heard that before. It could be that carriers alert to flight attendants but usually it is a chime. Maybe someone else on here can shed a better light on it.

I don't recognize it either. I was expecting it to maybe be a Config Gear warning or one of the rarely selected altitude tones for the GPWS landing altitude callouts (as opposed to the voice callouts), but he's in the passenger cabin, not the flight deck. Also, it's not likely the crew would be chiming the flight attendants that low on approach. At that point the cabin should be secure, the flight attendants safety seated and the Pilots fully attending to business up front.
 
tb727
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RE: 737-200 "horn" Sound

Thu Jun 06, 2013 1:07 am

The PNF owes the PF a beer. That's the gear horn.
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spudsmac
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RE: 737-200 "horn" Sound

Thu Jun 06, 2013 4:37 am

Apparently, a lot of transport category aircraft have horns to get the attention of ground crew. This could just be a case of one of the pilots activating it for whatever reason.
 
KELPkid
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RE: 737-200 "horn" Sound

Thu Jun 06, 2013 5:45 am

Quoting tb727 (Reply 3):
The PNF owes the PF a beer. That's the gear horn.

Might have been on purpose. Looks like the bird is holding altitude during the entire length of the clip...you'd burn a lot of extra gas to do that with the wheels out. Of course, if you're skipping checklist items, that would be a big no-no. Seems a little low to be cruising around with the wheels up to me   Of course I'm 100% back seat driver (by quite a few rows) in this instance...  
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
DUSint
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RE: 737-200 "horn" Sound

Thu Jun 06, 2013 1:18 pm

Quoting tb727 (Reply 3):
The PNF owes the PF a beer. That's the gear horn.

Thank you!
Never thought such a signal could be that loud.

Quoting KELPkid (Reply 5):
Might have been on purpose. Looks like the bird is holding altitude during the entire length of the clip...

This could be.
As far as I know the 732 has to fly a special approach (and departure) "slope" because of noise regulations (in the EU). As I am no expert I won't try to elaborate this further but maybe this has something to do with it?
 
tb727
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RE: 737-200 "horn" Sound

Thu Jun 06, 2013 2:08 pm

Quoting DUSint (Reply 6):
Thank you!
Never thought such a signal could be that loud.

It is pretty loud, some are louder than others in the same fleet. I was coming up the aft airstairs on a 727 just yesterday and the FO was testing the fire warning and I could hear it all the way back there even with all the noise that was going on.

Quoting KELPkid (Reply 5):
Of course, if you're skipping checklist items, that would be a big no-no. Seems a little low to be cruising around with the wheels up to me   Of course I'm 100% back seat driver (by quite a few rows) in this instance...

They may have been getting vectored around, told to slow, noise sensitive areas or whatever but it didn't look out of the ordinary at all to me. And yes, some guys will pull it back enough to get the horn to go off and say you owe me a beer, then do it again a minute later and say it again. We do it to the FE all the time. It will go off at any altitude in my airplane, so when we start the top of descent and start pulling power off, you say "coming back" and usually the FE or sometimes the PNF will grab it before it goes off. Some found that the old tic tac box will fit perfectly under the gear horn handle but I forbid anyone from trying that trick if I am on the airplane. That horn is there for a reason.
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Jetlagged
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RE: 737-200 "horn" Sound

Thu Jun 06, 2013 9:19 pm

Quoting tb727 (Reply 7):
It is pretty loud, some are louder than others in the same fleet. I was coming up the aft airstairs on a 727 just yesterday and the FO was testing the fire warning and I could hear it all the way back there even with all the noise that was going on.

It is loud, but the gear warning on the 737 (and the 727) is much lower pitched than that. As the OP said it sounds like a train whistle.

Here's a video shot in a 737 classic full flight simulator. At 07:14 the gear warning horn sounds when flap 1 is selected. Totally different sound to the one in the OP's video.

http://www.youtube.com/watch?v=zvSwy7bqdaE
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
David L
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RE: 737-200 "horn" Sound

Thu Jun 06, 2013 9:59 pm

Quoting Jetlagged (Reply 8):
Here's a video shot in a 737 classic full flight simulator. At 07:14 the gear warning horn sounds when flap 1 is selected. Totally different sound to the one in the OP's video.

http://www.youtube.com/watch?v=zvSwy...bqdaE

Um... that appears to be the same video as in the OP.  
 
tb727
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RE: 737-200 "horn" Sound

Fri Jun 07, 2013 12:47 am

Quoting Jetlagged (Reply 8):
It is loud, but the gear warning on the 737 (and the 727) is much lower pitched than that. As the OP said it sounds like a train whistle.

Fly them for a living, guarantee that's the gear horn. You owe me a beer!
Too lazy to work, too scared to steal!
 
AA737-823
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RE: 737-200 "horn" Sound

Fri Jun 07, 2013 7:21 pm

Quoting tb727 (Reply 10):
Fly them for a living, guarantee that's the gear horn. You owe me a beer!

Our 732's didn't have such a horn, or at least if they did, I (as the mechanic) never heard it. You'd get a "TOO LOW - GEAR!" from the EGPWS, or (I thought) a takeoff config horn (WOMP WOMP WOMP), but I've never heard this noise come out of any 737.

So, assuming it's a difference in cockpit aural warning equipment, the question now is WHY it sounded briefly twice, and then for a longer period the third time? Or why it sounded three times at all...
 
mandala499
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RE: 737-200 "horn" Sound

Sat Jun 08, 2013 4:54 pm

Quoting Jetlagged (Reply 8):
It is loud, but the gear warning on the 737 (and the 727) is much lower pitched than that. As the OP said it sounds like a train whistle.

I've heard that sound before, albeit slightly lower. The gear horn is lower pitched, if you're in the cockpit. Once you get into the cabin, the lower frequency sounds from the horn gets muffled... but only heard it that high in the cabin once.

The other possibility is the Altitude Alert Horn, the standard ones aren't that high, but heard non-standard altitude alerter horns that go that high... but not that loud that it can be heard in the cabin like that. Not sure if Aviogenex had a mod done to their 732s...
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barney captain
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RE: 737-200 "horn" Sound

Sat Jun 08, 2013 9:03 pm

If it were the gear horn, why is it intermittent?

Look at the LED's - they are in the full extend position which means the flaps are beyond 10. If memory serves, the only way to silence the gear horn in that situation is to lower the gear.
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Tristarsteve
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RE: 737-200 "horn" Sound

Sun Jun 09, 2013 3:18 pm

I remember the 732 from when I last did hangar work on them in 1986.
I can't remember a gear horn, but we had an indication of gear not down. With the throttles at idle, and the gear up, the main gear red unlock lights come on, and stay on until the throttles are advanced, or the gear lowered. I found this out the hard way when I first did gear retraction tests in the hangar, and thought the red unlock lights were a fault. I was really running around until the next shift arrived, and he pushed the throttles fwd.
 
barney captain
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RE: 737-200 "horn" Sound

Sun Jun 09, 2013 6:41 pm

You will get the gear horn in that situation (gear up, thrust levers idle) when you select flaps. This can be silenced with the horn cut-out just below the flap lever. However, this cut-out only works on flaps 1-10. At flaps 15 and beyond, regardless of thrust lever position, the gear horn will sound and cannot be silenced.

Which brings us back to the video.

AFAIK, the only way that could be a gear horn is;

The gear is up

The Flaps are 10 (LED's are fully extended)

And the thrust levers are being brought to idle from above idle 3 times.

The problem with that explanation is there doesn't appear to be any change in sound wrt the thrust. It seems very constant, and doesn't explain why the horn was not cut-out. Every 737 driver learns quite fast where that cut-out button is and usually hits it within a nanosecond of the first indication of it sounding.

I'm still not convinced it's the gear horn.
Southeast Of Disorder
 
DUSint
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RE: 737-200 "horn" Sound

Sun Jun 09, 2013 9:07 pm

At first I would like to say that I do not question any of all your assumptions - esp. tb727 seems to be quite sure that it is the gear horn and I am not the one having experience with any aircraft apart from travelling in them...

However I am somewhat confused that this sound should be some kind of warning for the cockpit crew.

Therefore, I will try to describe the sound a bit more in detail - because you can't get every bit of information out of the video sound:
1.) It really sounded as if it came from outside the plane. If it wouldn't be so unrealistic, I would say there was a train horn mounted on the outside of the fuselage...  
2.) It had a distinctive resound/echo effect - sorry, can't describe it better, running out of words... Not echo like in the mountains, more like in a concert hall.

So, could this still be a/the gear horn?
 
DL_Mech
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RE: 737-200 "horn" Sound

Mon Jun 10, 2013 1:15 am

Is this the 727 gear horn? (At 1:00, 1:07, 1:26)

http://www.youtube.com/watch?v=W_ErZ1nakd0&t=0m59s
This plane is built to withstand anything... except a bad pilot.
 
tb727
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RE: 737-200 "horn" Sound

Mon Jun 10, 2013 2:24 am

Quoting DL_Mech (Reply 17):
Is this the 727 gear horn? (At 1:00, 1:07, 1:26)

Yep, it is.
Too lazy to work, too scared to steal!
 
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Jetlagged
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RE: 737-200 "horn" Sound

Tue Jun 11, 2013 7:08 pm

Quoting tb727 (Reply 10):
Fly them for a living, guarantee that's the gear horn. You owe me a beer!

For saying it isn't like a 727 horn perhaps (it's been a very long while since I was in a working 727 simulator so DL_Mech's youtube video was an interesting reminder). It is indeed quite like a 727 horn, but it's still subtlely different, and I still don't think it sounds at all like a 737 gear horn. The second and third time it sounds it's at a higher pitch than the first time. That can't happen with the gear horn. So the beer's on ice for the moment.  
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
tb727
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RE: 737-200 "horn" Sound

Wed Jun 12, 2013 2:46 am

Quoting Jetlagged (Reply 19):
That can't happen with the gear horn. So the beer's on ice for the moment.

Haha, ok, sounds good to me!
Too lazy to work, too scared to steal!
 
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HAWK21M
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RE: 737-200 "horn" Sound

Thu Jun 13, 2013 10:22 am

Sounds more like Cabin chime....signalled by Flt or Cabin crew to alert all FAs.
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