A320 German-wings accident in Southern France

[Buzzard]

This is not the sort of "Breaking News" I want to wake up to.
You just have to feel for all those involved.

 

[RooFlyer]

The lack of a radio call is not relevant. <snip for space>

Interesting things. Stable heading. Reasonably stable sink rate. 3,500 fpm is not as extreme as being intimated by some. You don't hit it every day in normal ops, but easily attained if you want. To give you an idea, the 380 can probably hit 9,000 in a high speed descent with speed brake. QF30 descent was about 5,000 fpm.

Thanks JB; the most sensible and concise commentary (hope you don't mind that term) from any source I've seen/heard so far!

 

[Mogul]

From Sky News:


Aviation expert Neil Hansford says the most crucial aspect in what is the worst air disaster on French soil in decades is 'that at no stage did the captain or first officer put out a mayday signal'.
Early indications are that the pilots may not have been 'in control of the environment', Mr Hansford told AAP on Wednesday.
'The aircraft was 46 minutes into the flight, it was at the top of its cruise altitude at 48,000ft and then in eight minutes dropped 32,000 feet,' he said.
- See more at: No distress signal during plane's plunge


More non factual reporting 48,000 ft no wonder there was no communication from the coughpit.

 

[mannej]

More non factual reporting 48,000 ft no wonder there was no communication from the coughpit.

Or a lack of proofing as it seems as if it's a simple typo?

 

[jb747]

I must admit that I have real trouble with the 'experts' that they trot out. Most don't seem to have ever flown anything bigger than a billy cart.

Looking back at the Flightaware data that was posted earlier, and doing some conversions to numbers that are actually used in the coughpit makes for interesting reading. I can't correct for wind, because I don't know what it was, but making a bit of a stab at it....

The aircraft descent seems to be at a pretty much constant mach number (somewhere around .8), until around the 25,000 foot level, when the mach starts to decrease, and the IAS sits at a reasonably constant figure of about 340-350 knots. As I understand it, the A320 max speed is .82 mach and 350 KIAS. So basically, this descent looks to be pretty much what you would expect if you flew current cruise mach number into max IAS. There's a term 'crossover altitude' which is pertinent here. That's the point at which climb/descent and aircraft transition from flying IAS to mach, and vice versa.

If you initiate a descent, with the autopilot engaged, at a constant mach number, the IAS will slowly increase as you descend. Eventually your desired IAS will reach the current mach, and the aircraft switches to flying IAS. If you were to wind the speed dial to the barber's pole (bricks), the aircraft would descend at max mach (minus a buffer, but not material) into max IAS.

So, what would the switch sequence of an emergency descent look like? It starts with putting your mask on, then there is a PA (which was mandated after Helios...serves no purpose), then seat belts, and then you get the descent happening...
1. Altitude dial...turn and pull. It's just flicked down to a low altitude...refined later.
2. Heading turn and pull. Get yourself away from the current track (just in case there is someone under you). For reasons of ergonomics, most people turn to the left, because it's the same dial motion as used on the altitude selection.
3. IAS dial. Pull. That locks in the current mach number.
4. The altitude selection should have commanded the engines to idle, but make sure now.
5. Speed brakes.
6. Speed select the max appropriate.

So where does that leave us? An emergency descent, with full speed brake and very high speed, should give a rate of descent that is appreciably higher that seen here. I'd expect something like 6,000 fpm. But, the RoD does seem to fit pretty well with partial speed brake and the high speed. It almost looks like they did items 1-4, and then stopped.

Pure conjecture, but I don't see flight controls....

 

[Quickstatus]

I must admit that I have real trouble with the 'experts' that they trot out. Most don't seem to have ever flown anything bigger than a billy cart.

Looking back at the Flightaware data that was posted earlier, and doing some conversions to numbers that are actually used in the coughpit makes for interesting reading. I can't correct for wind, because I don't know what it was, but making a bit of a stab at it....

The aircraft descent seems to be at a pretty much constant mach number (somewhere around .8), until around the 25,000 foot level, when the mach starts to decrease, and the IAS sits at a reasonably constant figure of about 340-350 knots. As I understand it, the A320 max speed is .82 mach and 350 KIAS. So basically, this descent looks to be pretty much what you would expect if you flew current cruise mach number into max IAS. There's a term 'crossover altitude' which is pertinent here. That's the point at which climb/descent and aircraft transition from flying IAS to mach, and vice versa.

If you initiate a descent, with the autopilot engaged, at a constant mach number, the IAS will slowly increase as you descend. Eventually your desired IAS will reach the current mach, and the aircraft switches to flying IAS. If you were to wind the speed dial to the barber's pole (bricks), the aircraft would descend at max mach (minus a buffer, but not material) into max IAS.

So, what would the switch sequence of an emergency descent look like? It starts with putting your mask on, then there is a PA (which was mandated after Helios...serves no purpose), then seat belts, and then you get the descent happening...
1. Altitude dial...turn and pull. It's just flicked down to a low altitude...refined later.
2. Heading turn and pull. Get yourself away from the current track (just in case there is someone under you). For reasons of ergonomics, most people turn to the left, because it's the same dial motion as used on the altitude selection.
3. IAS dial. Pull. That locks in the current mach number.
4. The altitude selection should have commanded the engines to idle, but make sure now.
5. Speed brakes.
6. Speed select the max appropriate.

So where does that leave us? An emergency descent, with full speed brake and very high speed, should give a rate of descent that is appreciably higher that seen here. I'd expect something like 6,000 fpm. But, the RoD does seem to fit pretty well with partial speed brake and the high speed. It almost looks like they did items 1-4, and then stopped.

Pure conjecture, but I don't see flight controls....

Sorry JB747:

IAS = Indicated airspeed?

 

[jb747]

Sorry JB747:

IAS = Indicated airspeed?

Yes. It's probably more correctly CAS (calibrated airspeed), but we don't need that much detail.

 

[Quickstatus]

It will be interesting to see how the airbus design philosophy regarding command authority factor into this accident

 

[jb747]

It will be interesting to see how the airbus design philosophy regarding command authority factor into this accident

Yes, but that only relates to flight controls. There is nothing here to indicate (from the limited data) any involvement of either flight controls or laws. The protections basically only issue pitch up, or down commands, in response to either angle of attack limits, or overspeeds. Neither would ever give what appears to be a very stable descent. Nothing about the data looks to be uncommanded.

 

[RooFlyer]

JB, would you be able to construct a reasonable involuntary / no human control scenario, starting from the info in paragraph 3 in your post above?

 

[jb747]

JB, would you be able to construct a reasonable involuntary / no human control scenario, starting from the info in paragraph 3 in your post above?

In which the aircraft started the descent itself? No.

The fact that the heading and rates, and the speeds, seem so stable, and to fit speed crossover so well, points to the autopilot being engaged. Whilst AB will hold an attitude very reliably if the a/p is disconnected, I don't think the result would be quite as steady.

I've just had a look at some of the flight recorder data that I have for QF30, and the entry to the descent doesn't look all that different.

We're playing with incredibly limited data though.

 

[Mrmaxwell]

The BEA have announced they have been able to retrieve a workable audio file from the CVR and it contains information right up until impact - only a matter of time now until some solid details emerge I imagine.

They also announced they found the container for the black box however the actual unit was not inside so the search continues.

 

[jb747]

I do hope that's the case, though at the moment the net seems to have contradictory info. Supposedly the data recorder is missing its memory module. Given that they are supposed to survive incredibly hard impacts, it gives an idea of just how bad this was.

The analysis of the CVR won't be a simple case of listening to a dictaphone recording. All of the background sounds will be analysed, with frequencies and any changes used to try to put together what happened. And once the data recorder information is available, there is a very painstaking matching of the timelines.

 

[QF WP]

A very unexpected twist if the reported story is true:

AS investigators go through the audio recovered from one of the Germanwings black boxes, reports have emerged that one of the pilots became locked out of the coughpit and was unable to get back in.
The New York Times reports that a senior military official involved in the investigation described “very smooth, very cool” conversation between the pilots during the early part of the flight from Barcelona to Dusseldorf.
The audio then seems to reveal one of the pilots left the coughpit and was unable to get back in.
“The guy outside is knocking lightly on the door and there is no answer,” the investigator said. “And then he hits the door stronger and no answer. There is never an answer. He said, “You can hear he is trying to smash the door down.”

No Cookies | The Courier-Mail

 

[amaroo]

Given the conjecture with MH and now this - they might have to start thinking about having three pilots as a safety net e.g. two in the coughpit at all times.

 

[michaele]

This opens a range of new questions:

http://mobile.nytimes.com/2015/03/26/world/europe/germanwings-airbus-crash.html

 

[yohy?!]

so its now looking like either the pilot in command became incapacitated or intentionally locked out the copilot and crashed the plane - terrible either way

 

[mannej]

so its now looking like either the pilot in command became incapacitated or intentionally locked out the copilot and crashed the plane - terrible either way

And it ponders the question, is it time to look at the systems and structures in place regarding access to the coughpit?

 

[Quickstatus]

http://www.nytimes.com/2015/03/26/world/europe/germanwings-airbus-crash.html?_r=0



pilot locked out.


speculating:

what happens to autopilot when pilot in command is incapacitated. Will inadvertent bumping against any controls by a slumped incapacitated pilot turn off autopilot?.
it seems not to be the case here because the descent appeared controlled and then levelled out.

Suicide?

 

[juddles]

Yet another suicide. :/