PPRuNe Forums - United 777 "dives" after takeoff from OGG

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- - United 777 "dives" after takeoff from OGG (https://www.pprune.org/accidents-close-calls/651344-united-777-dives-after-takeoff-ogg.html)

My bad. Your linked page shows me 12/18/2022 06:54:02 PM as time stamp. In the link I see your correct z time. Will delete my posted link. The page seems to show a different timezone, even for historic data. Sorry about the confusion.

You decide about the time zone for the page. There is the gear icon for settings.

I don't know how Simon on the Avherald can come to that conclusion. Planes just don't loose 1,400ft within the span 12 seconds. That comes out to a roughly -7000fpm descent (TAC reports -8,600fpm, so close enough). Something did indeed happen during that departure. FR24 doesn't just randomly start outputting such extreme values.

Quote:

Originally Posted by VHOED191006 (Post 11388119)

Simon is a great journalist when it comes to fact, research and reporting. He is excellent at ferreting out information from all sorts of sources.

Sadly, though, he has a pretty shaky grasp of technical stuff (like many journalists) - some of his previous ADS-B-based "analyses" have been woeful.

Stick to what you do well, Simon.

Quote:

Originally Posted by VHOED191006 (Post 11388119)

Setting up a 7000+ rate of descent in 12 seconds is not that easy. You would have to push hard and fast forward. Negative G.
This rate points toward a windshear/microburst event.
A microburst may be difficult to see on a radar. I flew through one many years ago. Only had small red dots on the radar. Heavy rain in the shear, speed increased fast followed by fast drop in speed as we passed under the microburst. Massive rain. All we could manage was a steady descent at ref -10, throttles fully forward and one dot low on the glide.
As we passed out of the shear, airspeed increased really fast again.

Quote:

Setting up a 7000+ rate of descent in 12 seconds is not that easy. You would have to push hard and fast forward. Negative G.

I don’t buy that at all. 200 Kts is about 20,000ft/min. Sine 20 degrees is about 0.34. So setting -20 degrees would easily give you 7000 ft/min rod and easily achieved in 12 seconds.

I used to fly rotary and had an opportunity to do some work with the senior Honeywell scientist on EGPWS. I took him for a jump seat ride once and I showed him how quickly rate of descent built up with pitch down. From 145 kts cruise I selected -5, -10, -15 degrees pitch down (separate demos). The rate of increase in rate of descent was eye watering. It was connected to seeing how the Mode 1 alerts could be improved.

Wonderful story, love it. This may be anothercase where the system saved lives numerous.

Do you think it may have been the man himself?

Quote:

Originally Posted by 212man

So setting -20 degrees would easily give you 7000 ft/min rod and easily achieved in 12 seconds.

But we're not talking about a chopper, we're talking about an in-trim (I assume) Boeing 777 that was probably around 10° nose-up. To have the nose go down to -20° in 12 seconds would indeed be "not that easy". It would have required some very positive action on somebody's/something's part.

Quote:

Originally Posted by tubby linton (Post 11385839)

The Rate of Descent achieved is very close to that of AF447 when it was stalled. The published fact that both pilots have been retrained suggest that a stall occurred rather than Mother Nature interfering.

How does it suggest that?

I suspect that had there been even an incipient stall, albeit not an actual one, that might still have triggered a few flags in the training department.

Latest from Jon Ostrower:
https://theaircurrent.com/aviation-s...ted-1722-maui/

Quote:

NTSB releases uninformative preliminary report on United Maui dive
Air safety reporting by The Air Current is provided without a subscription as a public service. Please subscribe for all scoops, in-depth reporting and analyses.

The National Transportation Safety Board quietly released a bare-bones and uninformative preliminary report as part of its investigation into the United Airlines Boeing 777-200 that went into a sharp dive and recovery shortly after takeoff from Maui in December.

The investigation into the still publicly unexplained December 18 dive is unusual for the NTSB, which launched the investigation on February 14 only after the occurrence was revealed publicly by The Air Current on February 12. At the time, the NTSB said that it expected a preliminary report within two to three weeks.

The NTSB almost always begins an inquiry immediately following an incident or accident — in sharp contrast to the eight weeks that followed the incident aboard United 1722 — and the lack of a template for a multi-month delay has been awkward for the safety board.

Quote:

The NTSB initially told TAC on April 21 that while the investigation was still ongoing, it was not planning to release a preliminary report and that was common for some investigations. After TAC sought an accounting of earlier NTSB inquiries that did not receive preliminary reports, the agency clarified and said after seeking an internal accounting of similar incidents "there was no such list."

NTSB spokesman Peter Knudson attributed the confusion to the NTSB having "updated some report writing and releasing processes and it seems there was a lack of clarity related to the preliminary report releasing process."

"There will, in fact, be a preliminary report," said Knudson on April 24. "It will not, however, contain a factual narrative but only 'data blocks' as they are known."

The just-released preliminary report was devoid of any contextual information beyond the incident's location, the flight's destination and the aircraft type and registration. The board's initial February 14 tweet announcing the investigation described the incident as one "in which a United Airlines 777 lost altitude before recovering shortly after departing." That description was not included in the just-released preliminary report, which does not make it clear what the NTSB is investigating.

"The narrative will be included in the final report along with the probable cause and any contributing factors," said Knudson, who expected the final report on the Maui incident to be released this summer.

Write to Jon Ostrower at [email protected]

I don't know what the non handling pilot was doing. However to help stay out of trouble, do this. Select the required flap setting. Keep your hand on the lever until the indication, indicates what you have selected. When that is done, realise the lever, whether it be u/c or flap while in transit, keep your hand on the lever. I have seen it from time to time.. Select and forget? Not good enough. Asking for trouble, if that was what happened.

Quote:

Originally Posted by RichardJones (Post 11426355)

Keep your hand on the lever until the indication, indicates what you have selected.

..Really??..Impossible..Non-flying pilot supporting the PF by setting headings, altitudes, radio frquencies etc during a climb in a busy airspace..Cannot do that with the hand on the flap lever..

Fly Safe,
B-757

golly that was untidy. The QAR data will tell the full story, the continued flying and delayed reporting will have lost the DFDR. Doesn't sound like a W/shear event, it does hint of disorientation, and crew input resulting in the dive and recovery. The report of going through an extra flap setting is not that big a deal on a B777, for that setting, getting rid of the LE slats would be a bigger problem, in the absence of evidence, that may have been more of a problem, but the B777 will tolerate a F5-F1 error without becoming catastrophic. The response seems to be from the flight crew, not the weather, if the GS has any validity. Not a nice day out.

Quote:

Originally Posted by B-757 (Post 11426385)

I didn't know whether to laugh or cry. So I did both.🤣😭

Vertical speed and pitch attitude continued a negative downward trend to reach a maximum of -8,536 feet per minute and -16.74 degrees respectively while at 1,386 feet (radio altitude)

Docket

This'll be good...

Wow!

Pretty much as I expected. No one was monitoring the instruments for a significant period of time. This happened after an issue with flap selection/overspeed. The focus by the pilot flying on flap concerns instead of instrument scan was long enough to result in an undesired flight condition.

While hand-flying is nice, using the autopilot in more challenging conditions can have the advantage of allowing one to have more focus on other distractions while the automatics take care of aircraft attitude.

NTSB final report via Flightradar 24:
https://www.flightradar24.com/blog/w...nal_Report.pdf

Quote:

Originally Posted by Capn Bloggs (Post 11482754)

NTSB final report via Flightradar 24:
https://www.flightradar24.com/blog/w...nal_Report.pdf

They managed to turn a pretty innocuous mistake into a near-disaster. I find it interesting that the PF's reaction to impending overspeed during initial climb was to reduce thrust rather than pitch up.