Vietnam 787 No gear down
Surprised, this has not been mentioned before.
How can a 787 get to (alleged) 650ft and not realise gear not down? https://simpleflying.com/vietnam-air...g-787-gear-up/ Have I missed something on this story? |
They would have realised by the warning systems in place , whether that prompted action we don’t know |
Prompted by ATC
https://www.atsb.gov.au/publications...r/ao-2019-051/ |
The gear warning comes on at 800 feet AGL off the radar altimeter in the 787. Probably got the warning about the same time ATC was calling. |
Originally Posted by Sailvi767
(Post 10574720)
The gear warning comes on at 800 feet AGL off the radar altimeter in the 787. Probably got the warning about the same time ATC was calling. |
Originally Posted by Sailvi767
(Post 10574720)
The gear warning comes on at 800 feet AGL off the radar altimeter in the 787. Probably got the warning about the same time ATC was calling. |
Originally Posted by roundsounds
(Post 10574789)
Melbourne is 400’ AMSL, FR24 data shows 650’ making it around 250’ AGL at the GA?
Given that it corresponded to at a point 1.6 nm from the THR, then I suspect they weren't actually at 250' AGL. |
FR24 displays Altitude based on Standard Pressure. If there is a large difference between that and the local QNH, you will need to apply the difference to see the real altitude. I recall the local QNH at the time was 1027mb. That’s a 420 feet adjustment. |
Plus crew reaction time |
What is the terrain like on the approach? If it slopes upwards towards the runway, then 800ft on the radio altimeter may be low in reference to the runway threshold.
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Originally Posted by Capt Fathom
(Post 10574827)
FR24 displays Altitude based on Standard Pressure. If there is a large difference between that and the local QNH, you will need to apply the difference to see the real altitude.
I recall the local QNH at the time was 1027mb. That’s a 420 feet adjustment. So that would make the altitudes at the initiation of the GA (approximately): Mode C/Mode S: 650' AMSL: 1050' AAL: 625' Rad Alt/AGL: obviously dependent on terrain (if anyone with local knowledge can help, it was 1.6 nm from the THR, roughly overhead the Keilor Stadium) |
Originally Posted by DaveReidUK
(Post 10575040)
So that would make the altitudes at the initiation of the GA (approximately):
Mode C/Mode S: 650' AMSL: 1050' AAL: 625' Rad Alt/AGL: obviously dependent on terrain (if anyone with local knowledge can help, it was 1.6 nm from the THR, roughly overhead the Keilor Stadium) |
On the Boeing 777 you would get a config warning if you select land flap and the the gear is not down, so the warning would come at about 1500 AGL. I wonder why the logic is different on the 787. |
Originally Posted by suninmyeyes
(Post 10575148)
On the Boeing 777 you would get a config warning if you select land flap and the the gear is not down, so the warning would come at about 1500 AGL. I wonder why the logic is different on the 787. |
Originally Posted by suninmyeyes
(Post 10575148)
On the Boeing 777 you would get a config warning if you select land flap and the the gear is not down, so the warning would come at about 1500 AGL. I wonder why the logic is different on the 787. A landing gear is not down and locked and one of these occurs:
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I’m sure they have a gear warning when you select landing flap without gear down as well, same as the 737. That will happen much earlier. |
Originally Posted by suninmyeyes
(Post 10575148)
On the Boeing 777 you would get a config warning if you select land flap and the the gear is not down, so the warning would come at about 1500 AGL. I wonder why the logic is different on the 787. |
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..
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Strange
To me this whole situation seems really strange, either the plane was not configured for landing, or the bells& whistles did not work. Alternatively the twr was wrong |
Originally Posted by Capt Fathom
(Post 10574827)
FR24 displays Altitude based on Standard Pressure. If there is a large difference between that and the local QNH, you will need to apply the difference to see the real altitude. I recall the local QNH at the time was 1027mb. That’s a 420 feet adjustment. |
Originally Posted by hans brinker
(Post 10575500)
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....
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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... |
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. |
Originally Posted by Smythe
(Post 10576190)
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... |
Originally Posted by Centaurus
(Post 10575343)
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.... |
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/ |
Originally Posted by India Four Two
(Post 10576760)
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! |
Originally Posted by India Four Two
(Post 10576760)
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/ PPRN at its finest, a true learning network!! |
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. |
Originally Posted by jmmoric
(Post 10578122)
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. |
Originally Posted by DaveReidUK
(Post 10578233)
See posts #7, #8, #11, #20 and #21.
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Originally Posted by jmmoric
(Post 10578263)
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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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. |
Originally Posted by wiedehopf
(Post 10578424)
Some newer aircraft also transmit the QNH used by the pilots.
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Maybe they tried to mimic this MD-10 approach? :} |
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