Vassili Zaitzev
Master Sergeant
if the stall was uncontrollable, no doubt the plane accerlated beyond it's safety limits. That may be why the plane broke up in midair.
Air france flight from Brazil to Paris
- Thread starter Torch
- Start date
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
Matt308
Glock Perfection
Nobody read (or perhaps understood) Muller's post.
vikingBerserker
Lieutenant General
It's really odd that the pilot never radioed anything.
Vassili Zaitzev
Master Sergeant
Matt, I read it, but really didn't understand it. Sorry, got a little complicated, I'll take another gander.
Vassili, I'll try to paraphrase from what I understand. Matt, please correct anything which isn't correct.
As an aircraft flies higher, the stall speed increases, and the critical mach number decreases. Eventually you reach a point where the two are almost the same figure. Any faster and you will get mach tuck (nose pitch down, and more over-speed), any slower and you will stall the aircraft (nose pitch up in a swept wing aircraft).
There are other things which affect the stall and cricical mach speeds, such as temperature, so I would guess, theoretically at least, severe up/down drafts could have placed them in 'coffin corner'.
As an aircraft flies higher, the stall speed increases, and the critical mach number decreases. Eventually you reach a point where the two are almost the same figure. Any faster and you will get mach tuck (nose pitch down, and more over-speed), any slower and you will stall the aircraft (nose pitch up in a swept wing aircraft).
There are other things which affect the stall and cricical mach speeds, such as temperature, so I would guess, theoretically at least, severe up/down drafts could have placed them in 'coffin corner'.
syscom3
Pacific Historian
Matt, I read it too.
But those airframes are quite strong. We've all seen the video's of wings being stressed to the breaking point. I cannot imagine anyone certifying (or insuring) the aircraft if it busts up during a stall.
But those airframes are quite strong. We've all seen the video's of wings being stressed to the breaking point. I cannot imagine anyone certifying (or insuring) the aircraft if it busts up during a stall.
Vassili Zaitzev
Master Sergeant
Ok, that makes sense. Thanks Gumbyk!
Matt308
Glock Perfection
Once the any large Part 25 airplane departs normal flight, the stress on the airframe is enormous. I will not even postulate that is what happened. But if it did the implications are likely catastrophic.
seesul
Senior Master Sergeant
anoter article A week later, Air France mystery deepens - CNN.com
any aircraft could break up during a stall, it all depends on the severity of the stall, all aircraft are designed to with stand 3 G's, most airliners are designed to withstand 8 or more as a one of but it wouldn't be the first time an airliner has exprenced more than it could stand
epically if you took into account partially damage from hail, which would increase the stalls speed and damage the airframe
FLYBOYJ
"THE GREAT GAZOO"
Remember, we are not talking normal 3 g stresses which most airlines are certified to. FAR Part 25 gives Specific requirements that are the minimum requirements and it is expected that for the most part commercial aircraft will be operated within the envelope established. What happened to this aircraft seems to be abnormal. We'll see as more more data is collected.
The Basket
Senior Master Sergeant
- 3,712
- Jun 27, 2007
Aint the Airbus designed to stall nice?
Gentle nose drop? Not exactly 9g. And isn't the FBW to stop overstress? More questions.
More I know is the less I know in this crash as things contradict.
If the aircraft had pitot issues then the pilots would have had plenty time to radio and the aircraft would not fall apart because of this.
My view is that either went into the storm to slow and stalled but surely it would recover? Or it was attempted recovery and high speed close to sound and it couldn't take it and fell apart? But the FBW would have done a safe pull out.
Or it lost all electrics but why would it do that?
Only the black boxes will tell...
Gentle nose drop? Not exactly 9g. And isn't the FBW to stop overstress? More questions.
More I know is the less I know in this crash as things contradict.
If the aircraft had pitot issues then the pilots would have had plenty time to radio and the aircraft would not fall apart because of this.
My view is that either went into the storm to slow and stalled but surely it would recover? Or it was attempted recovery and high speed close to sound and it couldn't take it and fell apart? But the FBW would have done a safe pull out.
Or it lost all electrics but why would it do that?
Only the black boxes will tell...
Burmese Bandit
Senior Airman
- 474
- Dec 5, 2008
What the Basket said!
Matt308
Glock Perfection
Yes you are right. But read the ACARS msgs. The FCC/Autothrottle disconnected. FBW bye bye.
Yep. Thus not a good idea to speculate. There are more msgs with periodic reporting that includes winds, temps, lat/longs and time. [proprietary]
Not necessarily. Only if they immediately recognized the problems. Rather, they likely just recieved a series of fault messages on the EICAS that caused them to resort to the QRH/POM. Pilots are trained to perform tasks that are detailed in these manuals and NOT to deviate (in most ALL situations). Remember the rules of pilotage... aviate, navigate, communicate. In that order. It appears from the ACARS msgs that the time from faults to last communication was 3 min or less. Aviate.
The time AF447 indicated its position (via both voice/data periodic surveillance reports) NOAA shows that inclement weather showed severe storm cells in the area (up to FL520 and with upper clouds indicating -80C temps). The FBW (as you say) is not a 'fail safe' technology. And again... note that the autopilot/autothrottle apparently disconnected. There is also another msg indicating "alternate control law" which might be a reversionary mode of operation from the FBW back to analog (note that this is my guesstimate as I am not an A330 FCC SME by any stretch of the imagination).
I keep reading this and from some official sources. Note sure where this comes from other than the ACARS fault codes. Yes, lots of the AF447 systems indicated faults. But this can also likely be attributed to the first loss of pitot probes (recall the A300 that augered into the ground after a maintenance action taped all the pitot probes closed and the pilots lost associated flight parameters IFR).
Yes. Thank God they aren't black. And let's hope we find them.
Matt308
Glock Perfection
Yet remember the American A300 tail failure?
Note the ACARS msg indicating rudder travel limiter fault warning. A pilot induced oscillation (stop-to-stop) has been proven to bring down a Part 25 airplane. Sys, it's not the stall that is catastrophic. It's the recovery. Again. Only supposition and nothing yet to support this... except a relatively fully intact tail...
Apparently the rudder limiter is governed by the airspeed. Loss of airspeed indication, could lead to loss of the rudder limiter/incorrect operation, which would allow pilots to make exessive control inputs. Would explain the ACARS warning regarding the rudder limiter.
One thing for sure, I'm learning a lot more about the systems in one of these aircraft than I ever did doing the ATPL pilots exam!
One thing for sure, I'm learning a lot more about the systems in one of these aircraft than I ever did doing the ATPL pilots exam!
Matt308
Glock Perfection
Yeah? Well, welcome to the forum. And that can be a two way street. So don't hold back on your own thoughts.
vikingBerserker
Lieutenant General
This just keeps getting more interesting. Im kinda surprised about finding bodies as I would have imagined wild life would have taken over.
wheelsup_cavu
1st Sergeant
Another twist in the story.
You would think they wouldn't have been allowed to board the plane.
Wheelsup
You would think they wouldn't have been allowed to board the plane.
Wheelsup
