Emirates B777 gear collapse @ DXB?
FullWings
Unless the Dunlops are already being tucked up in bed ... and there is one of the key questions. As an onlooker, I may presume that even ONE Trent 982 could overcome the extra drag of leaving the gear down for another 15 seconds. Does the PM make the call? If the PM was the FO, then we might expect life will be uncomfortable.
If you really want to go flying again, push the thrust levers forward and pull back on the yoke/stick when you’ve got enough airspeed. No intervention systems required. You can sort out the automation when safely climbing away...
PM will call positive rate, based on altimeter, VSI, radalt, etc. It is quite possible that those instruments did confirm the aircraft climbing but the airspeed would likely have had a nice negative trend arrow on it. In moments of stress we fall back on what we normally do and there may have been just enough confirmation to trigger the call from the PM.
Last edited by FullWings; 25th Aug 2016 at 08:01.
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atpcliff
I would like a discussion between you and M. Mouse because as TRE on 777 and 787 he feels it is categorically stated by Boeing. After SFO accident even FAA asked Boeing to have a look at the design off course it was one of the 31 factors contributing to the crash. It will be interesting for non 777 guys.
I would like a discussion between you and M. Mouse because as TRE on 777 and 787 he feels it is categorically stated by Boeing. After SFO accident even FAA asked Boeing to have a look at the design off course it was one of the 31 factors contributing to the crash. It will be interesting for non 777 guys.
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Full Wings:
If you have access to a 777 FCTM you will find that postive climb is NOT called with reference to the VSI or radalt but solely with reference to the altimeter.
About a third of the people I see in the sim are doing it wrong.
The VSI can and will show positive climb when the gear is on the ground because it is only a measure of acceleration.
The radalt reading is the delayed product of an algorithm and not a direct reading of height. Thus it can and will be tricked by aggressive handling in pitch as one might do in a windshear encounter near the ground.
If you have access to a 777 FCTM you will find that postive climb is NOT called with reference to the VSI or radalt but solely with reference to the altimeter.
About a third of the people I see in the sim are doing it wrong.
The VSI can and will show positive climb when the gear is on the ground because it is only a measure of acceleration.
The radalt reading is the delayed product of an algorithm and not a direct reading of height. Thus it can and will be tricked by aggressive handling in pitch as one might do in a windshear encounter near the ground.
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1104 comments later and we no nearer the truth of a crew surviving, photo'd fully documented FDR/CVR crash. Not even a sniff of a preliminary guess. Must make the rest of the B777 guys a bit nervous, not to mention Boeing.
Rat, Boeing, Rolls, and the NTSB are on-site and involved in the investigation, granted in an 'advisory' role - the local authority will be prime. So at some level Boeing knows what's going on. As I've mentioned previously, everyone involved is under something of a gag order - all information release should come through the local authority. Even around Boeing, information sharing is on a 'need to know' basis - in part to avoid leaks although it also comes in handy when the inevitable lawsuits start popping up. 
That's why I can publicly post about it - I literally know nothing about the investigation (insert poor Sargent Schultz imitation here 
). If I was in the know I'd need to STFU.
When the final report comes out, if Boeing or Rolls feel they've been unfairly thrown under the bus, then they can publicly disagree with the report - not before (see the Egypt Air 767 for a prime example).
That's why I can publicly post about it - I literally know nothing about the investigation (insert poor Sargent Schultz imitation here ). If I was in the know I'd need to STFU.When the final report comes out, if Boeing or Rolls feel they've been unfairly thrown under the bus, then they can publicly disagree with the report - not before (see the Egypt Air 767 for a prime example).
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I am curious to know what the crew did after what appears to have been the second landing. Would they have shut engines down or selected reverse thrust? Seems quite remarkable the aircraft slid along in a straight line for around 3000m with wings level. Helped no doubt by the large flat fairing over the gear bays. As the speed wound down did a point come when the aircraft had to tip to the left or right or were the crew able to influence this outcome in any way? It went right and then executed a turn to the right of around 155 degrees presumably because the right engine dug in. Aircraft comes to rest on approx heading of 275 and pictures show wind appearing to be blowing across aircraft at right angles ie from 185. How fortuitous this all happened with runway to spare ( though not much). I find it hard to believe reports that pax were unaware all this was going on.
Last edited by portmanteau; 26th Aug 2016 at 08:19. Reason: unplanned belly landing
Full Wings:
If you have access to a 777 FCTM you will find that postive climb is NOT called with reference to the VSI or radalt but solely with reference to the altimeter.
If you have access to a 777 FCTM you will find that postive climb is NOT called with reference to the VSI or radalt but solely with reference to the altimeter.
The VSI can and will show positive climb when the gear is on the ground because it is only a measure of acceleration.
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I alway thought the minimum concept of raising the gear was when the a/c fuselage was at a greater height than an extended gear AND increasing. Doesn't that fall under the Positive Climb definition which is confirmed primarily by an altimeter backed-up with a (I)VSI?
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"...What happens in specific, rare conditions where GA mode is not initiated even though selected ... Someone has overlooked the point; a hole in the logic or the text, a latent factor, a hole in the Swiss Cheese."
What happens is that pilots with reasonable survival instinct would become proactive and intervene MANUALLY by pulling back the stick/yoke/wheel and shoving and holding the throttles/thrust levers forward
We called sidestepping and ATC cleared Panam to take off on 6L. No ILS or VASIS on 6R. We came over the threshold of 6R slightly high due no glide slope. It was dark.
About 50 feet the wings rocked and the 737 seemed to fall out of the sky with PM calling urgently Vref minus 20. It happened so quickly. I instinctively firewalled the engines and pulled back to 15 degrees body angle on instruments and waited for the impact. As it turned out we caught the sink in time and the wheels did not hit before we climbed away.
The cause of the incident was the 747 had opened up to break-away thrust while on the taxiway at 90 degrees to 6R and we caught the jet blast from his engines as we passed behind him at 50 feet. If the crew of the 747 had acted immediately to taxi on to 6L when cleared by ATC the incident would have never happened. Instead the 747 crew failed to commence taxiing when cleared, maybe briefing or reading checklists while staying put on the cross taxiway before starting to roll on to 6L. It was an uncomfortable moment for us.
Last edited by Judd; 26th Aug 2016 at 12:15.
A thought re the lack of GA near touchdown. Is the aircraft still fail operational?
CS AWO 316
(a) The aircraft must be capable of safely executing a go-around from any point on the approach to touchdown in all configurations to be certificated. The manoeuvre may not require exceptional piloting skill, alertness or strength and must ensure that the aeroplane remains within the obstacle limitation surface for a Category II or III precision approach runway as specified in Annex 14 Chicago Convention.
(b) For decision heights below 15 m (50 ft) automatic go-around must be provided.
(c) When automatic go-around is provided, it must be available down to touchdown.
(d) When automatic go-around is engaged, subsequent ground contact should not cause its disengagement.
Also AMC AC 316 paras 1.1 b, and 2 c.
1 Safety Considerations
1.1 Effects of Contact with the Runway: For aircraft in which a go-around from a very low altitude may result in inadvertent runway contact, the safety of the procedure should be established giving consideration to at least the following:
The guidance information and control provided by the go-around mode should be retained and be shown to have safe and acceptable characteristics throughout the manoeuvre,
Other systems (e.g. automatic throttle, brakes, spoilers, reverse thrust and alerting systems) should not operate in a way that would adversely affect the safety of the go-around manoeuvre.
1.2 Inadvertent Go-around Selection. Inadvertent selection of go-around mode after touchdown should have no adverse effect on the ability of the aircraft to safely roll out and stop.
2 Performance
Height losses from a range of altitudes during the approach and flare should be determined when under automatic control and when using the landing guidance system as appropriate.
Height losses may be determined by flight testing (with typically 10 flight demonstrated go-around) supported by simulation.
The simulation should evaluate the effects of variation in parameters, such as weight, centre of gravity, configuration and wind, and show correlation with the flight test results.
Normal procedures for a go-around with all engines operating should be followed.
CS AWO 316
(a) The aircraft must be capable of safely executing a go-around from any point on the approach to touchdown in all configurations to be certificated. The manoeuvre may not require exceptional piloting skill, alertness or strength and must ensure that the aeroplane remains within the obstacle limitation surface for a Category II or III precision approach runway as specified in Annex 14 Chicago Convention.
(b) For decision heights below 15 m (50 ft) automatic go-around must be provided.
(c) When automatic go-around is provided, it must be available down to touchdown.
(d) When automatic go-around is engaged, subsequent ground contact should not cause its disengagement.
Also AMC AC 316 paras 1.1 b, and 2 c.
1 Safety Considerations
1.1 Effects of Contact with the Runway: For aircraft in which a go-around from a very low altitude may result in inadvertent runway contact, the safety of the procedure should be established giving consideration to at least the following:
The guidance information and control provided by the go-around mode should be retained and be shown to have safe and acceptable characteristics throughout the manoeuvre,
Other systems (e.g. automatic throttle, brakes, spoilers, reverse thrust and alerting systems) should not operate in a way that would adversely affect the safety of the go-around manoeuvre.
1.2 Inadvertent Go-around Selection. Inadvertent selection of go-around mode after touchdown should have no adverse effect on the ability of the aircraft to safely roll out and stop.
2 Performance
Height losses from a range of altitudes during the approach and flare should be determined when under automatic control and when using the landing guidance system as appropriate.
Height losses may be determined by flight testing (with typically 10 flight demonstrated go-around) supported by simulation.
The simulation should evaluate the effects of variation in parameters, such as weight, centre of gravity, configuration and wind, and show correlation with the flight test results.
Normal procedures for a go-around with all engines operating should be followed.
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There are suggestions throughout these posts that on this occasion, and possibly another, that there could be capability inadequacies in the aircraft and the crew. It is up to an investigation to determine the contributions of man, machine and environment.
autoflight: That may be true, but the B777 DOES meet all the certification requirements mentioned in PEI 3721's post above. Perhaps those requirements need a rethink (ie automatic go-around capability after touchdown??).
Last edited by BuzzBox; 27th Aug 2016 at 03:32.
Buzz, the thought #1112 was not intended to imply anything; certainly not right or wrong. The objective was to reflect on the general uncertainty and judgement required in aviation, including certification.
Assuming that the nuances of the GA mode were fully appreciated during certification (was this the flt test or the operational evaluation team), then the certification is based on the judgement of skill, alertness, safety, and acceptable characteristics. This opinion was most likely based on experiences and standards at that time, and where projecting this over the lifetime of the aircraft type would be extremely difficult.
Certification judgement remains a 'dark art'; any one view is unlikely to represent a world wide standard, nor accommodate changing standards overtime. Thus even though an aircraft has been certificated, certain aspects are open ended, based on assumptions which may longer hold true.
What operators lack is a clear explanation of what assumptions have been made during certification (skill, knowledge, workload, etc), i.e. operators lack guidance for determining procedures and training requirements. Also, any assumption has to be balanced by the likely human performance in a range of situations, not all of which can be foreseen.
It's all very well for NTSB to ask FAA/Boeing to review system designs, but unless there is a clearly defined standard for judgement, then the industry should not be surprised by a conclusion "that the system was alright then, so it's all right now".
This issue represents the growing gap between 'flying as imagined' at the time of certification and how flying actually takes place today; the regulators have to appreciate changes in the industry and avoid resorting to 'more training' for systems knowledge and awareness, where human limitations in memory and recall associated with these factors probably contributed to the problem.
You cannot expect to solve a problem with the same features which contribute to it.
Assuming that the nuances of the GA mode were fully appreciated during certification (was this the flt test or the operational evaluation team), then the certification is based on the judgement of skill, alertness, safety, and acceptable characteristics. This opinion was most likely based on experiences and standards at that time, and where projecting this over the lifetime of the aircraft type would be extremely difficult.
Certification judgement remains a 'dark art'; any one view is unlikely to represent a world wide standard, nor accommodate changing standards overtime. Thus even though an aircraft has been certificated, certain aspects are open ended, based on assumptions which may longer hold true.
What operators lack is a clear explanation of what assumptions have been made during certification (skill, knowledge, workload, etc), i.e. operators lack guidance for determining procedures and training requirements. Also, any assumption has to be balanced by the likely human performance in a range of situations, not all of which can be foreseen.
It's all very well for NTSB to ask FAA/Boeing to review system designs, but unless there is a clearly defined standard for judgement, then the industry should not be surprised by a conclusion "that the system was alright then, so it's all right now".
This issue represents the growing gap between 'flying as imagined' at the time of certification and how flying actually takes place today; the regulators have to appreciate changes in the industry and avoid resorting to 'more training' for systems knowledge and awareness, where human limitations in memory and recall associated with these factors probably contributed to the problem.
You cannot expect to solve a problem with the same features which contribute to it.
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There has been a lot of talk about windshear, pressure altitudes and temperatures, you have to realise these conditions are pretty well standard operating conditions for us in the summer, nothing special, it's what we are paid to deal with and do so on a routine basis. Are they a causal factor of course, but pitch without power is never going to make an airplane go upwards for very long
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It was the COMBINATION of a significantly elevated Density Altitude (Pressure, Humidity and Temperature) AND the existence of at least TWO different types of windshear, that are both likely to have been contributing factors to this accident.