United flight from Hawaii plunged to within 800ft of Pacific Ocean | Hacker News Reader

United flight from Hawaii plunged to within 800ft of Pacific Ocean

theguardian.com

38 pointsGabriel5442 comments

A bit concerned that all of the layoffs, forced retirements, and cost reductions in the airline industry have reduced the safety of commercial flights. There have been so many near incidents lately and they have all been unforced errors either by pilots or air traffic controllers who are either undertrained or overworked.

It seems especially crazy today where one could imagine much of the process could be heavily assisted by computers if the investment were to be made.

'Luckily, no accidents have happened yet, so we still have nothing to worry about'

-The US Govt

'oh, no, those accidents don't count'

Have they really? Or have airline near-crash stories for some reason been more popular on HN lately?

The article itself mentions all the recent events.

It's also disturbing that this wasn't self-reported. It isn't clear from the article what triggered the investigation.

It isn't even clear why this happened or why the plane entered into such a steep ascent afterward or why the flight wasn't canceled.

“The United Airlines flight crew reported the incident to the FAA as part of a voluntary safety reporting program. The agency reviewed the incident and took appropriate action,” the FAA told CNN.

https://www.cnn.com/travel/article/united-777-plunge-takeoff...

Thanks. I was also curious why the pilots didn't relay information back to air traffic control or why air traffic control didn't seem to notice it.

Originally reported by The Air Current here - https://theaircurrent.com/aviation-safety/united-maui-dive-u...

"The aircraft quickly recovered, but not before descending below 775 feet. Two people familiar with the incident said the climb produced forces of nearly 2.7 times the force of gravity on the aircraft and its occupants as that steep descent transitioned to an 8,600 foot per minute climb. The entire incident appears to have stretched no more than 45 seconds and in between radio calls with air traffic controllers in Maui, according to LiveATC recordings reviewed by The Air Current"

Later on in the article it states that no mention of the incident was made to Air Traffic Control and the flight continued on as normal.

I am surprised that the plane did not return back to its departure due to having exceeded manufacturing spec for maximum 2.3 G force to inspect for cracks in wings and fuselage.

Hopefully, that plane will be taken out of service in SFO.

  Hopefully, that plane will be taken out of service in SFO.

Ron Howard as the narrator: it wasn't.

Edit:

The article I read said it was not. Actually, I don't see anything on the Guardian's article indicating any inspection was performed.

https://theaircurrent.com/aviation-safety/united-maui-dive-u...

  The Boeing widebody … was quickly turned around at SFO and departed to
  Chicago on its next flight about two and a half hours later.

The article said it was inspected on landing at SFO.

so United wanted the full(er) inspection to be done at United O'Hare Maintenance Facility, got it.

  so United wanted the full(er) inspection to be done at United O'Hare
  Maintenance Facility, got it.

No. United has a massive maintenance base at SFO and this sort of inspection is important enough that you wouldn't put a plane back in revenue service without conducting a check.

COO Toby Enqkvist is stationed in Chicago.

And only the most rigorous inspections are done in O'Hare facility where all the best equipments are and under watchful eyes of executives.

This is expected given how many times FAA has hit United Airline in last 12 months for not doing safety inspection.

So I am guessing it went to ORD.

  COO Toby Enqkvist is stationed in Chicago.

What? The COO is not going to be doing or overseeing the inspection.

  And only the most rigorous inspections are done in O'Hare facility
  where all the best equipments are and under watchful eyes of executives.

What? United Tech Ops is based out of SFO with a 2.9 million square foot facility. Yeah, there are like thirty other Tech Ops facilities, but the SFO facility is the largest and is obviously well prepared to carry out whatever inspection especially as the plane was already there.

  So I am guessing it went to ORD.

Yes, it flew to Chicago in revenue service. There is zero chance that United deferred an inspection until after a subsequent revenue flight. Not even Southwest is that bad (and they're the record holder for maintenance related fines from the FAA). From what I've read 2.5 hours is about enough time to do an inspection if no damage is found initially.

Huh, given the steep dive, and equivalently steep climb-out, I wonder if they got hit by a microburst?

Exactly - do we have confirmation it was actually a dive and not a downdraft/updraft? Because flying into a sudden downdraft would barely be noticeable by anyone who wasn't looking at instruments (you can still be climbing in air that is descending).

The verbs here are a bit alarmist - descended from 2200 to 800 feet over 45 seconds sounds less horrible - though this should have been reported even if just to NASA.

"Flight tracking data analysis revealed that the Boeing 777-200 had reached an altitude of roughly 2,200ft when it began a steep dive, descending at a rate of about 8,600ft a minute"

The article additionally says the entire ordeal lasted 45 seconds, but clearly part of that 45 seconds was a steep dive.

2200-775 = 1425ft total dive.

At a rate of 8600ft/min, they were in a dive for about 10 seconds. But obviously levelling off means a rate of dive a lot less than 8600ft/min.

Ya, at the rate described, it would have been more like 10 seconds of dive. Pretty scary if you are looking out the window I imagine. I mean, at the rate given, they were about 5 seconds from the water. I think that would have felt plenty dramatic to me.

I would assume that situational awareness for those inside the plane would have actually been pretty poor. They were climbing through clouds when the dive began so seeing the orientation of the plane to the earth would have been very spotty.

As a passenger, even if I couldn't see out the window, you'd definitely know you weren't going "up" anymore at that rate of decent. Combined with "we just took off" I'm certain that at least a few people in the cabin knew something really bad might have been about to happen.

  As a passenger, even if I couldn't see out the window, you'd definitely
  know you weren't going "up" anymore at that rate of decent.

No, you really wouldn't. Even for the pilots spatial disorientation is a real problem and they have instruments to show which end is up.

I follow most of my flights (especially takeoff/landing) with all the sensors in my smartphone. In flights without emergency events, the most useful for me is barometric pressure. When they suddenly drop the pressure by 20+% after achieving cruising altitude, half the plane shortly goes to sleep. I presume due to the lower partial pressure of oxygen.

Sure, but then you're talking 10,000 ft or more. The pressure differential between 2,200 ft and 775 ft is much smaller. It's possible some folks' ears popped, but IMO unlikely that they would've attributed it to a steep descent. Instead I'd expect folks chalked it up to the cabin pressurizing if they even noticed. If passengers noticed and thought there was something wrong this would've made news much sooner.

  I presume due to the lower partial pressure of oxygen.

Probably the lower oxygen content. My pilot friend claimed to have raised the cabin altitude a smidge back in the DC-10 days if FAs complained about e.g. noisy babies. I assume he's full of shit, but you never know.

> The pressure differential between 2,200 ft and 775 ft is much smaller.

Irrelevant. The cabin pressure is controlled independently of the Earth's environmental altitude pressure.

> Probably the lower oxygen content.

That's literally exactly the same thing as the thing that I said.

The cabin won't be noticeably pressurized at 2,200 ft. While a 777 will pressurize the cabin slightly before takeoff the max cabin altitude is 8,000 ft. So, yes, there is a bigger change in pressure during an approach (from 8,000 ft cabin altitude to roughly the altitude of the field) than there is going into a steep dive from 2,200 ft.

I might be stupid but I don’t understand what point you’re getting at?

No. In flight you are subject to variable G-forces so you can't know that you are moving in the way that you "feel" you are moving.

If you (or anyone) wants a really, REALLY good experience around this, go to your local small airport and find a flight instructor and ask them to show you "unusual attitudes" - they'll have you close your eyes and put your head down, do stuff with the plane, and then ask you what the plane is doing - you will say "turning down and to the right" and be in a climb to the left. It's freaky.

That's fair, I suppose a better way to word my point would be that any sort of "extreme" maneuver, absent some warning from the pilot about a rough takeoff or landing (or turbulence while in flight) is unusual for a passenger plane. Having that happen just after takeoff we're near the ground would give me some concern regardless of which direction I subjectively felt we were moving in, up or down. I've been through plenty of rough takeoffs and landings as a passenger and I just find it hard to believe that not a single person on the flight didn't at least think to themselves "hey, this isn't a normal climb to 10k".

  The verbs here are a bit alarmist

Nah, they're appropriate. Getting that low (less than 775 ft) is bad, doing that on climb out is worse. There's no margin for error at that height. Moreover the plane pulled 2.7G which is in excess of what the plane is rated for (2.5G). The pilots should've returned (to Maui or the Big Island) for an inspection instead of continuing on with the flight.

  though this should have been reported even if just to NASA.

What I've read is that the incident was reported after the flight landed at SFO.

What would NASA do with this information? Do they have an aviation incident response I’m not familiar with?

Yes, they operate the Aviation Safety Reporting System[1] in the US.

It’s intentionally kept separate from the FAA, which has the enforcement role, to encourage reporters to come forward. The second ‘A’ in NASA is ‘Aeronautics’, after all, so it’s a reasonable place to put this function. Reporting to ASRS comes with a certain degree of immunity to enforcement actions, and keeping it separate from the FAA reinforces that.

They have a monthly publication, Callback, which includes anonymised snippets of reports, with each issue presenting lessons learned and usually centred around a specific theme. It’s worth a look if you have an interest in how the US aviation system tries to prioritise safety.

[1] https://asrs.arc.nasa.gov/

This is eerily similar with this recent incident: https://avherald.com/h?article=504d75c7&opt=0

In the Qatar case, they mentioned that the pilot insisted on manually taking off and lost his bearing. The conditions look similar here and I wonder if it’s the same story.

probably not: https://news.ycombinator.com/item?id=34766838

I fly back and forth from Australia fairly often and it always gets bumpy south of Hawaii -- the worst was a thousand-foot drop that threw people around the cabin. I always keep my seatbelt on when transiting that area!

Between the passengers and the people who monitor aviation radio data, I'm surprised this story didn't come out sooner.

Could have been really crappy weather and a very turbulent flight. I'm not sure I would be able to tell the difference between 2.5g and some of the severe jolts I've been in.

US seems to be having more aircraft drama than usual lately, no?

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