Location: Blader som faller til jorden og blir til nye Traer
I don't know for sure whether or not the following has been linked here (I did a search and the search returned a null) but I found the following Aviation Week article 'High-Altitude Upset Recovery" most informative. There are even some comments by Captain C.B "Sully" Sullenberger.
Reading so many opinions over the past year about this unfortunate crash, it seems to me that the majority are picking up the story in the middle of the book. Most comments begin after the airspeed, auto pilot and auto thrust disconnect. For me, that is not where the story begins. It begins when the crew enter the flight dispatch/operations office in Rio. These 3 pilots about to take a flight at night over the ocean must have been given a weather briefing, weather maps and had to know what type of weather to expect in the ITCZ. Next, they must have checked the fuel uplift for the flight including fuel to circumnavigate the bad weather. In the CVR there doesn't seem to be any mention of the weather by anyone, neither any plan to skirt the CBs. When the captain left the flight deck, did he say anything about the ITCZ ? As the aircraft reached TOC, was the radar checked and set for inflight operation in cruise? You see, this is where the story begins. This is the beginning of the book. I will forever hold that this accident would never have happened if they had gone around the storm. That is where they screwed up royally. All the other stuff that has been discussed for the past year has nothing to do with what really caused this crash. They flew a perfectly good airplane into CBs that iced up the pitot tubes causing the loss of control. As for the heated pitot tubes, have you ever made the mistake of touching one on the ramp check? It will give you a really bad burn if the switch is in the on position. Don't forget that after lift-off they go to high power and get much hotter for flight. I will say again for the 10th time, you don't fly an airplane into CBs when close to the coffin corner. I only hope that everyone has learnt the lessons from this accident and will not repeat them. Thanks..
I take your point, but I think you go back a bit too far. Captain did caution the two remaining pilots to expect turbulence greater than they had experienced, and the crew discussed deviating "a bit left". Bonin even briefed the cabin (Maryann?) in regard the expected turb. Your conclusion that ice caused the IAS problem is not ironclad, the pitots failed simultaneously, and that speaks to other than blockage/ICE.
I rue the lack of CVR discussion, but unlike you, I do not conclude that the flightdeck was silent. I believe the bare minimum was released, and whether or not it was by the wish to slow public suspicion of a/c problems or for "discretion", we have a most incomplete and premature picture.
The speeds were odd, but not so unusual as to eliminate Windshear. TCAS and WINDSHEAR were present on ACARS, and remain unexplained; the actual speeds are after the fact, and a lack of comment initially by the Pilot flying might show that they indeed were not "crazy speeds" , except to say that the speeds may have given him the notion of overspeed, ("we have some crazy speed") not extremely low, as would be expected with pitot blockages. He has become pre-occupied with overspeed, is this in response to IAS? Surely not, unless he has sussed UAS, which most doubters refuse to alow him, due his "lack of training".
Smokin' Eddie, are you sure? That is not what I have found, and remain convinced the first evidence WE have is of PM annunciating "Lost the speeds, ALTERNATE LAW". This was at I think :16, eleven seconds post a/p loss. No?
organfreak. "Dollars to doughnut......" Hmm. Right, that is not speculation, that is an accusation. We should be better than gratuitously making wagers on a dead man's training. I still get chills when I put myself there.
See, here's the thing: UAS was not in the line quiver, it was poorly understood, and even after the wreck, AB was issuing..."DON"T re-select A/P, the a/c may CLIMB unexpectedly......." No one had conclusively decided whether or not to trust the STALLSTALL !! respect
organfreak. "Dollars to doughnut......" Hmm. Right, that is not speculation, that is an accusation. We should be better than gratuitously making wagers on a dead man's training.
Excuse me sir, with all due deference, I know exactly what I meant when I said that. It most certainly is speculation. I accuse him of nothing, but I suspect that he didn't know, based on his driving. "Dollars to doughnuts" is simply a colorful expression, and far from a serious wager. Engaging PLONKing device; I've read enough. BYE now!
Oh, and....speaking of "gratuitous," I'm speculating (again) that you are the only one here in the forum who doesn't believe the pitots were fouled by ice. Wanna know what I think? (Probably not.) Preposterous!
Let's not forget the PF did two things perfectly after the loss of the autoflight.
"I have the controls". Perfect.
Lyman: One thing....
I have the controls". Perfect.
Nothing from then on was perfect. Whatever he did to counter the right bank/nose down was certainly NOT executed anywhere near perfectly, with the end result being the same outcome as you postulate would have happened had he done nothing... just a number of seconds and wild ride later.
I have steered clear of commenting for a very long time, primarily because we have received nothing new to comment on. But you woke me up.
PNF said, “we’ve lost the speeds then,” then, ”alternate law protections
Thanks, Organfreak, Lyman, memory did not serve.
I just looked at the law matrix again, and note limitation of AOB to 67 deg is active in Alt 1. IIRC, the degradation kicked AF 447 into Alt 2, so stopping the roll (besides being standard airmanship in response to an undesired roll) would be the natural response, but also necessary since it won't stop itself.
Likewise the Pitch was trending up, from 0 degrees (-3 from a cruise setting) so not only was arresting and reversing ROLL important, but from PF's 'snapshot' of PITCH, his NU was not required, in fact, he should have left PITCH alone, but to my mind he didn't have the time to orient his inputs. So what ensued was what MB calls a potential PIO, and a robust NU that resulted ultimately in their demise. Inheriting a maneuvering a/c in those conditions may not be appreciated by the cognoscenti here. I continue to insist that the critical time frame is the twenty or so seconds either side of a/p loss. Sure CRM seems non-existent, and a basic understanding of what the sirframe was up to as well, however, once upset, the odds were long. Captain says it all: "We are going to crash, this cannot be..." "Climb", "No, No, don't climb." "Pull". "But I've been Pulling for some time". A regular CF, but the horse bolted long before this abject confusion. I am glad BEA are concentrating on HF, however, this wreck was not such an unexpected event, given the traps set for it right along. This flight was flukey, and an embarrassment to all involved. Such a loss.
It seems almost ridiculous the fact the aviation industry is still today using sub heated Pitot's.
Were they subheated ? Who had never a sudden pitot failure ?
AoA indicator is a mandatory solution after the AF447 loss of control, that has already been said by some of you.
But three systems (Airbus) may be replaced by five (Space shuttle), to have a better resolution of systems voting : With two pitots tubes blocked by ice the vote among three says these two are good ! And the third not blocked is supposed to be false... The vote among three is cheaper, the vote among five is much safer !
Better still with two only Pitot Tubes ! These two, if designed differently, but to spec/reg, will never fail simultaneously, the fail chain cannot be identical. It does not eliminate failure, only failure in concurrent fashion.
Three of the identical design/manufacture are three blind mice, identical triplets.
They didn't fail and certainly not simultaneously. if they clogged up for more than 10 sec. at the same time the ADR DISAGREE message would have been displayed at ~ 02:10:15 ISO 02:12:xx.
First RH(FO) Pitot freezed up, 5 sec. later LH probe, a few sec. later STBY probe which returned to normal value for a brief moment.
@02:10:20 LH and STBY returned - but faulty -.
@02:10:40 LH was back on line (correct displayed) and 5 sec. later also RH probe. (FDs returned and needs 2 valid speeds) At that time they switched over to ADR3 as source for RH PFD,
IMO If they didn't had done that action they would have had proper and coherent speed displays on both LH as RH PFD. (35 sec. after start of event)
ADR3 returned at 02:11:10. ADR 1 returned in ~30 sec., ADR 2 in ~35 sec. and STBY in ~1 minute.
loss of speeds thereafter caused by hi AOA & NCD ADIRU output.
@RRR: Don't know what you mean with 'sub'heated, its self temp. controlled. The heat applied is inversely proportional to the temperature of the probe.