Flybe AP has a 'Plummet' Mode?

[fenland787]

As I was only an occasional inhabitant of the Pointy End during flight my knowledge of Autopilot setting is limited to what I had to do to 'fly' the lab in Everett but I don't recall being able to set 'Plummet' mode?
(Edit - looks like the Beeb have decided 'drops' might be better than the original 'plummet' - they could be right but descends could be even better?)

BBC News

[PAXboy]

As it is reported that the pilot responded to the alarm and disconnected the autopilot = Job Done! OK, there was an error of setting but, despite an uncomfortable dip, the pilots flew the aeroplane. Another useless media item picking something from 11 months ago. However, as if warning were needed, every carrier has to be ready with the correct story and to present it quickly and fairly.

[DaveReidUK]

Originally Posted by fenland787

(Edit - looks like the Beeb have decided 'drops' might be better than the original 'plummet' - they could be right but descends could be even better?)

Hmmm. At 1100 ft AGL, ROD was 4300 fpm, one can perhaps understand the BBC's choice of words, however misguided.

Originally Posted by PAXboy

picking something from 11 months ago.

Picking up something from an investigation report released a few hours ago.

[Kerosine]

Mistake was made, very little actual risk unless pilots were asleep, looks good as a headline. Nothing to see here.

[WIDN62]

The AAIB thought there was something to see!

[jimjim1]

https://www.gov.uk/government/public...-november-2018

Direct link to Hi-Resolution pdf
https://assets.publishing.service.go...018_Hi_Res.pdf
30MB file. Low res one does not display diagrams well.

DHC-8-402 Dash 8 G-ECOE 11-Jan-18

IMC, autopilot configured and then selected so that aircraft would crash into the ground/sea in 54 seconds unless corrected by crew. Crew oblivious until ...

EGPWS warnings alerted crew who reacted with 36 seconds to spare. Airspeed had been 163 KIAS in climb and reached 235 KIAS in unplanned and unexpected descent. [these times are too generous. Less time was actually available]

After recovery they tried AP again with same settings.

Hardly a benign little excursion I wouldn't have thought.



ALtitude curve interesting

[25F]

SLF here so please excuse if these are dumb questions - but why is there not some sort of sensible minimum altitude for the autopilot? And why isn't the EGPWS connected to the autopilot to disconnect it or override it and start pulling up?

[reverserunlocked]

It’s a Q400. At that point you stop asking sensible questions and just shrug. The Q400 has a lot of oddities and the autopilot is one of them.

[ajamieson]

"Staff reported that the plane had become visual with the ground."

In much the same way that a drunk becomes visual with the ceiling?

[Aso]

"Staff reported that the plane had become visual with the ground."

OMG Johnson! Did you see that? There is a ground underneath us!

[pinkpanther1]

Originally Posted by fenland787

As I was only an occasional inhabitant of the Pointy End during flight my knowledge of Autopilot setting is limited to what I had to do to 'fly' the lab in Everett but I don't recall being able to set 'Plummet' mode?
(Edit - looks like the Beeb have decided 'drops' might be better than the original 'plummet' - they could be right but descends could be even better?)

BBC News

For takeoff the Flight director in the Q400 is set with the Vertical Mode ; GA (Go around) and the lateral mode HDG SEL (heading select). Further the assigned altitude for departure is entered with the ALT SEL (alt select) mode armed. In the Flybe case the crew forgot to input the assigned altitude and left it at 0ft. When they armed ALT SEL the flight director captured the assigned altitude of 0ft (as the aircraft was already at approx 0ft) This meant the vertical mode was in ALT. (i.e. the autopilot had been programmed to maintain 0ft. When the autopilot was engaged after takeoff at around 1600ft the flight director pitched down to returned to its assigned level of 0ft. This comes down to basic mode awareness of what the flight director is commanding given the stage of flight.

[infrequentflyer789]

Originally Posted by ajamieson

"Staff reported that the plane had become visual with the ground."

In much the same way that a drunk becomes visual with the ceiling?

IMC

So more like: came out of the cloud, realized pointing at the ground.

[Sailvi767]

Originally Posted by pinkpanther1

For takeoff the Flight director in the Q400 is set with the Vertical Mode ; GA (Go around) and the lateral mode HDG SEL (heading select). Further the assigned altitude for departure is entered with the ALT SEL (alt select) mode armed. In the Flybe case the crew forgot to input the assigned altitude and left it at 0ft. When they armed ALT SEL the flight director captured the assigned altitude of 0ft (as the aircraft was already at approx 0ft) This meant the vertical mode was in ALT. (i.e. the autopilot had been programmed to maintain 0ft. When the autopilot was engaged after takeoff at around 1600ft the flight director pitched down to returned to its assigned level of 0ft. This comes down to basic mode awareness of what the flight director is commanding given the stage of flight.

How at the moment of engagement does the flight crew not note the immediate nose down movement and disconnect the autopilot within 1 to 2 seconds. Basic airmanship dictates that any time a flight mode change is engaged or activated you verify the desired result is achieved.

[Vessbot]

Every once in a while I encounter a discussion that's a false positive hit against the typical notion of the sensationalist clueless media, and this is one of them. Nobody minding the store while it's plummeting (yes, plummeting) at 4300fpm below 1500 feet, finally to be woken up by WHOOP WHOOP PULL UP. Yes that is indeed a serious incident, and all of you pooh poohing it should imagine yourself in that circumstance, on a dead head or commute! Still "nothing to see here?"

That aside, can you have active FD modes on the Q with the FD hidden? That's the only possibility I can see, that can explain this. If the FD was set in a mode captured at zero altitude, and showing the severe nose down command to achieve that, who in their right mind would engage the autopilot?

[reverserunlocked]

Originally Posted by Sailvi767

How at the moment of engagement does the flight crew not note the immediate nose down movement and disconnect the autopilot within 1 to 2 seconds. Basic airmanship dictates that any time a flight mode change is engaged or activated you verify the desired result is achieved.

In fairness the report says the skipper responded almost immediately, but you can imagine that with engines at climb power (this was after the acceleration altitude) a nose down pitch to 0 feet would be pretty abrupt. Although the mode confusion wasn’t caught before it bit them, the report does commend the crew for their prompt actions after it happened.

[Vessbot]

Originally Posted by reverserunlocked

the skipper responded almost immediately,

It was 15 seconds from AP engagement and beginning of the pitch down to the EGPWS and corrective action. Right now, get out your phone or kitchen timer or whatever is within reach, and start it for 15 seconds. As it counts, close your eyes and imagine flying and/or monitoring the airplane, right after the off, and imagine it continuously pitching down as it develops a 4300 fpm descent rate, over the course of 15 seconds.

Does that feel like "almost immediately?"

[Fursty Ferret]

What purpose does routinely setting the MCP altitude to 0ft serve on the Q400?

[reverserunlocked]

Originally Posted by Vessbot

It was 15 seconds from AP engagement and beginning of the pitch down to the EGPWS and corrective action. Right now, get out your phone or kitchen timer or whatever is within reach, and start it for 15 seconds. As it counts, close your eyes and imagine flying and/or monitoring the airplane, right after the off, and imagine it continuously pitching down as it develops a 4300 fpm descent rate, over the course of 15 seconds.

Does that feel like "almost immediately?"

Ok I read it as they responded ‘almost immediately’ to the pitch down, not the ‘don’t sink’ cation. Although the report does say ‘Timely warnings of the hazardous flight path were provided by the EGPWS, and prompt corrective action by the PF returned the aircraft to safe flight’ so they are damned with some faint praise.

[Vessbot]

Originally Posted by Fursty Ferret

What purpose does routinely setting the MCP altitude to 0ft serve on the Q400?

I would guess that the last guy set it to zero after the flight, in an OCD fashion.

[DaveReidUK]

Originally Posted by Vessbot

I would guess that the last guy set it to zero after the flight, in an OCD fashion.

SOP, not OCD.

"The first sector was uneventful, and the aircraft landed on Runway 22 at Belfast City. While it taxied clear of the runway, the co-pilot carried out the ‘after-landing’ checks which included setting the autopilot selected altitude to zero."