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Vietnam 787 No gear down

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Vietnam 787 No gear down

Old 21st Sep 2019, 18:41
  #21 (permalink)  
 
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Originally Posted by hans brinker
Was just looking at the Denver Airport, saw several airplanes at 0feet. Unless they dug a 5280feet hole, I am pretty sure the altitude displayed is at least some of the time based on QFE, not QNH/QFE....
Nope. With WoW, altitude is always shown as zero, no QFE required.
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Old 22nd Sep 2019, 15:11
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Well, knowing where MEL tower is, if they observed no gear down, damn.....

Low drag approach on the 787??....that is a lot of energy to manage on that ac...

the crew did GA...
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Old 22nd Sep 2019, 21:31
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The crew went around.

Yes the alert maybe came earlier but perhaps the initial “oh crap” reaction was to drop the gear. Then realisation sinks in and a go around flown.

or perhaps a few seconds where taken in the cockpit “oops, we screwed up, ready to go around? Yup? Ok off we go”.

It doesn’t have to be an instant TOGA.
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Old 22nd Sep 2019, 21:35
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Originally Posted by Smythe
Well, knowing where MEL tower is, if they observed no gear down, damn.....

Low drag approach on the 787??....that is a lot of energy to manage on that ac...

the crew did GA...
Apparently it was Essendon Tower that noticed.
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Old 23rd Sep 2019, 02:11
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Originally Posted by Centaurus
In the old days it would be called a low drag approach. Saves fuel. Left the gear down selection a bit late, that's all..

ROFL

The poor schmuck can't win.... put the gear down too soon, you aren't efficient, put it down too late and ATC complain about the impending noise and FOD issue, and associated NOTAMS for runway closure. Now I recall one pilot who used to congratulate his FO's who out of an abundance of caution would lower the gear metaphorically at TOD.... he had a beef on contract terms with "the company". you just can't be too careful....


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Old 23rd Sep 2019, 02:30
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I think this is an appropriate thread to bring this great story by John Deakin to the attention of a wider audience:

Gear-Up Landing In A 747?
https://www.avweb.com/features/pelic...ding-in-a-747/
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Old 23rd Sep 2019, 20:10
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Originally Posted by India Four Two
I think this is an appropriate thread to bring this great story by John Deakin to the attention of a wider audience:

Gear-Up Landing In A 747?
https://www.avweb.com/features/pelic...ding-in-a-747/

Great reminder that we all are fallible India Four Two, thanks!

Last edited by Mariner; 24th Sep 2019 at 12:44. Reason: editorial
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Old 23rd Sep 2019, 20:45
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Originally Posted by India Four Two
I think this is an appropriate thread to bring this great story by John Deakin to the attention of a wider audience:

Gear-Up Landing In A 747?
https://www.avweb.com/features/pelic...ding-in-a-747/
Just superb. A 100,000 hour team of sky gods about to land a 747 wheels up.
PPRN at its finest, a true learning network!!
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Old 24th Sep 2019, 10:37
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Normally in older aircraft (I strongly suspect it's the same in newer aircraft), the altitude sent by the transponder is fixed at a standard QNH setting of 1013.25 hPa... So there is no connection between the altitude sent by the transponder and the shown value on the altimeter (where it can be adjusted by the pilots).

The secondary radar systems will the make the conversion to the altitude based on the local QNH that is inserted into the radar system (automatically or manually).

As long as the transponders all just transmit using the standard QNH setting, everything is fine... cause that also ensures the safety nets in for example ACAS, and radar systems....

The altimeter setting by the pilots versus the transponder altitude is what we confirm every time you show up on radar. Sometimes we catch a wrong QNH setting by the pilots, sometime we catch a malfunctioning transponder...

How flightradar24 handles it, I have really no clue... but I suspect it uses the transponder altitude as well, whether it calculates according to local QNH or standard pressure?

EDIT: A response to the FR24 users, not this case in particular.
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Old 24th Sep 2019, 12:27
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Originally Posted by jmmoric
Normally in older aircraft (I strongly suspect it's the same in newer aircraft), the altitude sent by the transponder is fixed at a standard QNH setting of 1013.25 hPa... So there is no connection between the altitude sent by the transponder and the shown value on the altimeter (where it can be adjusted by the pilots).

The secondary radar systems will the make the conversion to the altitude based on the local QNH that is inserted into the radar system (automatically or manually).

As long as the transponders all just transmit using the standard QNH setting, everything is fine... cause that also ensures the safety nets in for example ACAS, and radar systems....

The altimeter setting by the pilots versus the transponder altitude is what we confirm every time you show up on radar. Sometimes we catch a wrong QNH setting by the pilots, sometime we catch a malfunctioning transponder...

How flightradar24 handles it, I have really no clue... but I suspect it uses the transponder altitude as well, whether it calculates according to local QNH or standard pressure?

EDIT: A response to the FR24 users, not this case in particular.
See posts #7, #8, #11, #20 and #21.

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Old 24th Sep 2019, 12:50
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Originally Posted by DaveReidUK
See posts #7, #8, #11, #20 and #21.
Yes, it was meant as a reply to them. Just talking a bit about the secondary surveillance and transponder side of the case
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Old 24th Sep 2019, 13:29
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Originally Posted by jmmoric
Yes, it was meant as a reply to them. Just talking a bit about the secondary surveillance and transponder side of the case
Ah, OK. Your suspicion that newer aircraft also send altitude based on 1013.25 is indeed correct.
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Old 24th Sep 2019, 15:43
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All aircraft with altitude reporting transmit their pressure altitude. (altitude based on an altimeter set to standard pressure)

Some newer aircraft also transmit the QNH used by the pilots.
Also some report GPS altitude.

FR24 does not correct for QNH.
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Old 24th Sep 2019, 16:06
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Originally Posted by wiedehopf
Some newer aircraft also transmit the QNH used by the pilots.
Yes, in fact all aircraft that are equipped with EHS (Mode S EnHanced Surveillance) send the baro setting in the same transmission as Selected Altitude, though only when interrogated for it by a suitably-equipped SSR ground station.
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Old 25th Sep 2019, 14:45
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Maybe they tried to mimic this MD-10 approach?


Last edited by TopSwiss 737; 25th Sep 2019 at 15:58.
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