AF 447 Search to resume

[Lonewolf_50]

A chilling conversation

Our discussion on the choice of initial, and subsequent, search area has been made with the assumption that the pilots on the flight deck were behaving as rational actors in most respects. From this, we attempt to solve the mystery regarding how far and for what amount of time they remained "on original track." This leads to the perplexing question of

"How can they not have been further than position "X" based on time, distance, velocity, and eventual arrival at the ocean after descent at "Y" rate?"

There's a chilling possiblity that had not occurred to me until I spoke with some old colleagues (we had a twenty-five year reunion from our old squadron) all of whom are now in either the Passenger Carrying or Freight Carrying profession with such companies as AA / Delta / Southwest or Fedex / UPS.

That possibility: a delayed course change (to evade towering cells) that was in progress at the time of the upset, the course change delayed due to physical fatigue. I asked a few of the guys if they'd been watching this investigation (after we'd had a chat on the Cargo Crash in UAE), and Capt "H" very quickly opined the following:

"I think you'll find out the crew were asleep when they find the CVR."

I wasn't prepared to consider that.

I asked how the heck he knows that?

I pointed out that I understood the Captain to be in rest, per a typical long haul practice in many airlines, with two FOs alive and well on the flight deck.

Capt "H" nodded, and said quite simply that he finds the Occam's Razor explanation to be that the two on the flight deck nodded off. He'd had it happen to himself more than once when he was an FO. Typical happening was the Captain on a long haul would advise him "I'll be getting 40 winks, make sure I am awake in an hour" and before an hour is up, "H" with all great intention to stay awake, nodded off himself, to be awakened by said Captain a bit later ... but nothing bad happened in any of those cases ...

He then helped me understand what could happen.

NOTE: this is a bit of reasoning not intended to injure the rep of the gents on the flight deck that evening, but a way to address

"How did they not go further down intended track based on what is available to know from Wx and ACARS to date?"
(Idea being that they should have been farther down track from LKP).

With a scheduling variation that doesn't allow both of the co-pilots to quite adjust their circadian rhythms, they are by rule "crew rested" but in mid-cycle (circadian rhythms) on the day of this event.

So, per usual, Captain does take off, and a bit later goes off to rest bunk to be sure he's fresh for approach and landing later on in Paris. Two perfectly good and reasonably rested pilots/FO's are on the flight deck, but due to their Circadian rhythm being a bit out of synch, are on a not-quite-settled rest cycle. (I ran into this problelm in the fleet years ago when we began a few weeks of midnight launches, after a few months of mostly day and evening ops. It takes a few days to reset the clock ... we had a number of close calls with eyelids on pilots, and in one case a crewman who made the "wake up" call in time ... )

One nods off, then the other ... and by bad luck, none of the FA's or other Cabin Crew had occasion to communicate with the flight deck for any of the usual reasons. When the big cells appear on Wx radar, neither cued the other to avoid storm (stay with me here) since neither saw the display.

At little bit later (perhaps an FA knocks on the door with coffee?) one of the two awakens much closer to the storm system, and with a peak at the radar realizes

"Whoa, must deviate/change course, too close to storm system."

Being human, and not wanting the Captain to be angry for getting behind the situation, he has awakened his mate and is in process of a course change (both being in the "must sort this out and not get the Captain mad at us" mind frame) when they encounter the severe weather's effects on the airplane. (Note, this sequence of events also points to flying as a priority, aviate navigate communicate, and thus they don't get the message out to the pax "strap in, rough weather ahead" nor to the FA's. Playing catch up, and all that goes with it. Evidence points to quite a few folks not being not strapped in ... )

With (5 or 10 or 15? degree) AoB of turn, you lower your stall margin, right? (At those altitudes, and at that mach number, per previous posts in this thread, it's pretty obvious that one handles any turn with care.)

That aerodynamic reality suggests that if this course change were in progress, the stall occurred in turning flight rather than in level flight ... with the idea that the stall was triggered by hitting unstable air with less stall margin than one normally carries.

This might explain the upset in the first place. (Reduced stall margin).

To compound that, pitot tubes all iced up won't help them after upset occurs, and they have bad to no airspeed information (at least initially) in their scan as they attempt to recover from the upset.

With this unexpected event confronting them, crew for one reason or another (many such reasons were discussed in massive depth in this thread for the past year and a half) were unable to recover.

While attempting to, they were not heading in the general direction of the original flight planned route, but in a turn (one way or the other) away from flight planned route. This changes/reduced the time and distance clicking away. This proposed scenario may resolve the puzzle over why they were this close to LKP.

The other chilling idea based on Capt "H" and his Occam's Razor -- nod off and just fly into the cells -- doesn't answer the problem of "so close to LKP" and isn't something to discuss in the context of

"How do you decide where to look and why, based on a datum of LKP and an estimate of upset based on ACARS?"

BEA had to make some assumptions on where to place datum and where to begin their search. If the assumption included "generally heading along original course from this flight plan" it could explain why they didn't look closer to LKP.

If I remember rightly, early on in the discussions here on PPRUNE forums, some folks had raised that idea of a nod off. It is not my intention to resurrect that zombie, but to apply that idea to the possible effects of track and thus location of the wreckage based on LKP.

Apologies if I was not clear about that earlier.

I am not sure if Capt "H" is right. His remark got me thinking that AF447 migh have been making a course correction/deviation around the cells when an upset occurred, with consequences that I had not yet seen in our lengthy discussion here.

EDIT: I had to revise this a bit to make it clearer.