United Airlines dives to 700ft above the ocean

Improper use of VS mode? It’s happened before…
 
Juan Browne postulates that perhaps someone had the altitude setting at zero, nobody caught it during pre-takeoff, and upon engaging the AP, the plane dutifully obeyed.
 
Tools said:
It’s happened before…
Click to expand...
A month ago in a Qatar 787 dropping to 800’ with a decent rate of -3000 fpm. Also just after takeoff. Stated reason was loss of SA.

“The first officer was flying the aircraft manually and without flight director indications, and lost situational awareness, sending the aircraft into a 3,000 foot per minute descent. The descent was so steep that the sink rate exceeded the flap speed limits, as the plane was flying over 300 knots true airspeed at that point.

The captain then took control of the aircraft, and managed to recover it at an altitude of 850 feet. Keep in mind at a descent rate of 3,000 feet per minute (and the rate usually increases quickly if you’re sinking), that 787 was less than 20 seconds from having a very different ending.”

https://onemileatatime.com/news/qatar-airways-pilot-loses-situational-awareness/

upload_2023-2-14_5-42-48.jpeg
 
If 9k fpm ROD is accurate, that jet was like SIX seconds from impact! Big if… but still…

Presetter doesn’t make sense in that context. Some sort of automation misuse seems HIGH on the list…

AND CONTINUED is what perked my ears… in what universe is THAT ok?
 
Kenny Phillips said:
Juan Browne postulates that perhaps someone had the altitude setting at zero, nobody caught it during pre-takeoff, and upon engaging the AP, the plane dutifully obeyed.
Click to expand...

It doesn't seem possible that the pilots could be that inept.
 
I downloaded the granular CSV data file from flightradar24, with data entries about once per second. And I added two columns of my own: vertical acceleration (difference in consecutive vertical speeds) and difference in consecutive tracks.

The autopilot does look like it was flying during the first few seconds of the plunge, with a steady track. But hand flying appeared to start at 1350' (row 98) when the track got more irregular and the vertical acceleration became positive (meaning that the negative rate of climb diminished). So it looks like a pilot took control then, pulled hard on the controls.

Curiously, there was another smaller event earlier in the climb (rows 70-81) when the vertical speed was down to just +512 fpm.
 
Many VS modes do not have stall protection. Seems to fit. What equipment?
 
The autopilot on this plane reminds of the Tesla one.

If it sees the ground coming, (or a kid on a baby carriage) it will plow right through it!

But seriously, I can't believe autopilot on aircraft this costly and which carry hundreds of passengers are so dumb.

Hey Boeing, can you just add a few lines of code like this to your autopilot?

AbnormalNoseDive()
{
If
AOA > 30 AND AGL < 1000
Then
(AlertPilot)
(ResumeSafeStraightnLevelFlight)
(MessageAirlineWithIncidentInfo)
}
 
NoHeat said:
Curiously, there was another smaller event earlier in the climb (rows 70-81) when the vertical speed was down to just +512 fpm.
Click to expand...

That could be starting acceleration and flap retraction.

Apparently the weather they launched into was quite bad too.

The alt preselect theory doesn't make sense to me.
 
Himayeti said:
The autopilot on this plane reminds of the Tesla one.

If it sees the ground coming, (or a kid on a baby carriage) it will plow right through it!

But seriously, I can't believe autopilot on aircraft this costly and which carry hundreds of passengers are so dumb.

Hey Boeing, can you just add a few lines of code like this to your autopilot?

AbnormalNoseDive()
{
If
AOA > 30 AND AGL < 1000
Then
(AlertPilot)
(ResumeSafeStraightnLevelFlight)
(MessageAirlineWithIncidentInfo)
}
Click to expand...
MCAS, my friend, MCAS.
 
Thought I saw they continued… surely that discounts any fire…
 
NoHeat said:
I downloaded the granular CSV data file from flightradar24, with data entries about once per second. And I added two columns of my own: vertical acceleration (difference in consecutive vertical speeds) and difference in consecutive tracks.

The autopilot does look like it was flying during the first few seconds of the plunge, with a steady track. But hand flying appeared to start at 1350' (row 98) when the track got more irregular and the vertical acceleration became positive (meaning that the negative rate of climb diminished). So it looks like a pilot took control then, pulled hard on the controls.

Curiously, there was another smaller event earlier in the climb (rows 70-81) when the vertical speed was down to just +512 fpm.
Click to expand...
How closely does your vertical acceleration column come to the G forces stated in the news? I think I saw 2.7G mentioned somewhere. If my brain is working today, that would come out to (2.7 - 1) * 9.8 m/s^2 * 3.3 ft/m * 60 s/min = 3300 fpm/s.
 
iamtheari said:
How closely does your vertical acceleration column come to the G forces stated in the news? I think I saw 2.7G mentioned somewhere. If my brain is working today, that would come out to (2.7 - 1) * 9.8 m/s^2 * 3.3 ft/m * 60 s/min = 3300 fpm/s.
Click to expand...

Oh, good question.

I calculate a peak of 2 g measured over 3 seconds, and 1 g over 7 seconds.

I did that by fitting the raw altitude data points to a parabola, y = y0 + 0.5 a t^2, for just a few data points near the bottom of the plunge. The ADSB data, while good enough for most purposes, aren't presented frequently enough for calculating the 2nd derivative during an abrupt maneuver, but fitting is the approach that makes the best of the situation.

Passengers would feel a pretty solid push downward into the seat, 3g peak, because on top of the 2g of airplane acceleration, their butts feel also 1 g of gravity in the same downward direction.
 
From another website:

A message from a friend:
Gusty takeoff, heavy rain, heavy plane, short runway, and at night. Used flaps 20.
At accel height, CA (PF) called for flaps 5. FO went through the gate and selected flaps 1. When climb rate dissipated, CA looked over to see the lever and unknowingly banked over as well. CA became disoriented and neither pilot noticed the dive until the GPWS warning. 2.7Gs at 775’ AGL to recover.
https://www.pprune.org/accidents-cl...777-dives-after-takeoff-ogg.html#post11385071
 
Last edited:
2.7Gs is absolutely no joke. The passengers surely felt that!
 
Too much automation skills and not enough flying skills. Modern automation will do that to even the best pilots. Children of the magenta line just enhance that.
 
Himayeti said:
The autopilot on this plane reminds of the Tesla one.

If it sees the ground coming, (or a kid on a baby carriage) it will plow right through it!

But seriously, I can't believe autopilot on aircraft this costly and which carry hundreds of passengers are so dumb.

Hey Boeing, can you just add a few lines of code like this to your autopilot?

AbnormalNoseDive()
{
If
AOA > 30 AND AGL < 1000
Then
(AlertPilot)
(ResumeSafeStraightnLevelFlight)
(MessageAirlineWithIncidentInfo)
}
Click to expand...

They forgot the semicolons. Code didn't work. No wonder there was an issue.
 
Quote rom PPRUNE:

QUOTE:
jdorenbecher

Former pilot and I was on that flight on that day. Shortly after TO the pilot slightly retarded the engines. I noticed it but it was subtle. Then we started sinking. The aircraft did not nose over into a dive. It felt like we were hit with a downdraft. Many screamed and the crew increased thrust and recovered and climbed up to FL39 and smooth air. I normally don't get too bothered by turbulence but I knew we were very close to the water having only been in the air for slightly more than a minute.


Sounds more plausible. I have encountered up or downdrafts crossing a shore line, but not this dramatic
 
More from the day of the incident:

Quote Hi, how about a date-and time check ?
Just 4 hours before this incident, HA 35 had the severe turbulence that injured many.

Both cases are weather related, I´d say. Unquote
 
DavidWhite said:
It’s only gonna get worse. Much worse.

We’re about to be in a world where the only PIC experience some MAJOR AIRLINE CAPTAINS have is as a Flight Instructor.
Click to expand...
It’s already happened here at DL. Word from check airmen is they’re doing just fine. Supposedly this United crew was experienced.:dunno:
 
geezer said:
Quote rom PPRUNE:

QUOTE:
jdorenbecher

Former pilot and I was on that flight on that day. Shortly after TO the pilot slightly retarded the engines. I noticed it but it was subtle. Then we started sinking. The aircraft did not nose over into a dive. It felt like we were hit with a downdraft. Many screamed and the crew increased thrust and recovered and climbed up to FL39 and smooth air. I normally don't get too bothered by turbulence but I knew we were very close to the water having only been in the air for slightly more than a minute.


Sounds more plausible. I have encountered up or downdrafts crossing a shore line, but not this dramatic
Click to expand...
This doesn’t sound like it was written by an airline pilot.
 
geezer said:
Quote rom PPRUNE:

It felt like we were hit with a downdraft.
Click to expand...
Click to expand...
I listened to a passenger's description on Fox News last night. He said the same thing and described an experience that sounded a lot like a microburst encounter to me: A slight reduction in power followed a bit later by the big descent. That reduction could have been in response to an increasing indicated airspeed as the downdraft was entered. The high "g" could be the result of a maximum lift climb to mitigate the descent rate. YMMV.
 
dtuuri said:
I listened to a passenger's description on Fox News last night. He said the same thing and described an experience that sounded a lot like a microburst encounter to me: A slight reduction in power followed a bit later by the big descent. That reduction could have been in response to an increasing indicated airspeed as the downdraft was entered. The high "g" could be the result of a maximum lift climb to mitigate the descent rate. YMMV.
Click to expand...

Sounds more plausible than "pushed wrong button on the autopilot". Same day as the Hawaiian Airlines turbulence injuries.

The "retraining" the crew received could have been weather related.
 
The flap retraction overshoot (FO) and subsequent instrument crosscheck bone-up to (CA) to a GPWS glove save narrative is the one being discussed on our side of things by our UAL peeps. Indoc classmate of one of ours, EWR777FO. No "autopilot mismanagement" as part of that narrative btw (that was just that boobtoober blancolirio adding his own 777 autopilot inside baseball tangent). I'd post the discord chat screenshot, but I don't care for the @ me back and forth, so people can go ad hominem to their heart's content over on APC.

I've lost friends in this business to spatial D, we're all fair game to boning it up, technical IMC not even required. The thin blue line stuff on the UA APC subforum is unreal. I'm more surprised at that reflexive face-saving than I am at the notion (not ludicrous to me) that there might be a cancer of instrument crosscheck handflying atrophy metastasizing in American 121. That isn't a problem of inexperience either, or "ethnic diversity" for that matter (unreal that has to be even debated).

As to pax talking about deck angle, good luck with that at night in the black hole, looking 90 deg off through a periscope. A boned-up flap over-retraction while slow[er than desired] and heavy will have a sink feeling without a negative change in aircraft pitch. They're out to lunch with the microburst theory imo.
 
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