CONF iture;
Thanks very much for the correction. Something more learned. That does shed more light on what was going on. PJ2

Thanks. HN39 and PJ2,
Hope this discussion I started about the possible use of pitch versus FPA as a poor-man's AoA indication hasn't been too much of a red herring. As CONF iture points out, it's probably inapplicable to AF447, but may even have been useful to someone – who knows?

In mind of what BOAC says, if we were going to use AoA in a jet upset, we would need a pure feed from an AoA probe, preferably independent of the AD computer; with a clear presentation – probably on an autonomous display. I am inferring that none of us is convinced its provision, and the extra training required, would be worthwhile.

Specifically, re AF447, I agree particularly with PJ2's last paragraph (today, 1315z), and CONF iture's remarks make sense.


Bergerie1,
Once was enough for me. Never thought I'd see an indication below 95 kts on my ASI (in flight) on a VC10. Forgot they had to mount a special vane, as the clever AoA probes (not vanes) on the aeroplane were themselves subject to the test. Presumably, they soldier on in the RAF.

Chris Scott;
In my view, not at all. As we all wait for more information, this both keeps the discussion alive and current; the side-discussions are well worth pursuing. I remain hopeful that there will eventually be hard information from the recorders for us to discuss.

Hi,

Gees .. how we are far from AF 447 Search to resume
Like the VS .. this topic is drifting and I estimate the point of origin there (with some divergences depending of the posters currents :) )

http://www.pprune.org/rumours-news/3...ml#post5536841

If I were as clever as some ..I'm sure .. in some days this topic will deflect to the problems encountered during the design of fire piston rings of the engine Rolls Royce Merlin ... :)

Discussions above are interesting but deserve a other topic

Indeed, jc- after post #482 I decided to give up and join the fray!

BOAC ... :ok:

Off Topic
 

The moderators in their wisdom anticipated the whims of the many to continue the technical what-ifs discussion and indeed created a separate more learned thread in the technical forum section.

Alas nobody ventures therein, very often, and the visible threads in this section get all the traffic:}

I keep checking this thread to see what is being done continuing the search for the aircraft but all posts have nothing to do with the thread title. Non relevant info seems to be filling the lack of information. Are any ships or submarines with monitoring equipment on station? We know it will be a difficult job to find the aircraft. How are they trying to do it? Anybody?

p51guy
 

Try post #533. There are other posts scattered about. Looks like the start of the next phase of the search is imminent. Good luck to them.

Hi Mustang Man,

Try harder? We've had at least 4 updates in the last 7 days - courtesy of Backoffice, mm43, and broadreach (thanks, guys) - re the progress of
"Seabed Worker" and "Anne Candies" towards the crash area.

Most of us are not competent to discuss nautical matters, so I guess we've been killing time by chewing over a few thoughts, most of which relate to possible upset scenarios. As lomapaseo points out, it seems we should really be doing it on another thread that has disappeared below the surface...

lomapaseo, Chris;
Agreed. And yes, the search updates are here, recent and available but you're right - so few can talk about that aspect.

I suppose the difficulty in breaking off to a different forum is continuity between the primary discussion, (AF447 Search to resume), what happened between 0209 and 0215 or so, and, because the BEA interim report points to a fully-stalled airplane when it hit the water, (whether we agree or not), how and why such event may have come about, all of which grow out of the original "tree" as it were.

We generally don't know beforehand that the thread is going to branch or at what point the dialogue should split to the Technical Forum and then, once discussed, return to the original topic. In the present case, perhaps a split probably should have occurred the moment that AoA/FPA/Stall behaviour branch was identified but none of us know what a "branch" is until we're well along it and by then it has a history within the larger threads. I know I'm a troublemaker when it comes to drift...:}
PJ

Not trying to start anything here, but "thread drift" is a common (too common) complaint, I've been reading here of a great deal that has to do with jet upset, sensing and instrumentation. It continues to be a riveting discussion, and like the DA says, "Your Honor, goes to background". "Very well, counselor, I'll grant some leeway here." Sonar, deep quest, and boxes are in here, necessarily, but I see this continuing discussion as quite germane, and conducted by experts. I bow to the discretion of the Mods.

As evidence I would cite the manual, the 'drill', Pitch/Power, AoA, and relateds as part of a picture that needs a flexible frame. imo.

bear

Actually, if you do want to go nautical for a while, the BEA have organised some serios kit complete with cranes, check out their boats here:-

Seabed Worker:-
http://www.seabedgroup.no/attachment...WORKER-007.pdf

Anne Candies:-
http://www.phnx-international.com/Ve...20AUG%2008.pdf

bear;
I think so...it's been (and is) very worthwhile and I think contributes to an understanding of the airplane involved as well as some aerodynamics. I agree that drift is something to avoid generally but I think here the Mods have chosen well to permit the wander. PJ

:hmm:

No trouble, it's just human nature

One man's drift is another mans passion for learning and understanding:ok:

AoA In Airliners
 

As a U.S. Navy pilot, maybe I can give some insight to this. At least one reason is that there is prejudice against the use of AoA indications in transport and patrol aircraft in the Navy. The attitude has traditionally been that "jets are for kids". (This was primarily in the days when transport and patrol aircraft were all prop driven.) Maybe that attitude still prevails.

Navy flight procedures are codified in the Naval Air Training and Operating Procedures Standardization (NATOPS) program. Periodic review conferences are convened among fleet operators, the Naval Air Systems Command, the Naval Air Test Center, representatives of the Chief of Naval Operations, and the manufacturer of the aircraft.

In the mid 1960s, I was sent as the representative of the Naval Air Test Center to a P-3 NATOPS conference to review and approve proposed changes in procedures. The P-3 Orion was an outgrowth of the Lockheed Electra and had, as standard equipment, a direct reading AoA gauge. (Maybe someone can tell us if the Electra had an AoA gauge.) In accordance with instructions from my boss, I proposed and argued for the routine use of AoA in various flight regimes, particularly in landing approaches and in wave-off situations (Go Around to you airline folks). It would also be useful in an inadvertent stall situation (which you shouldn't get into to begin with). The conference would not have anything to do with it. Their response was literally "that's only for jets." They simply would not agree to use something that in fact provided useful information. Maybe that attitude still prevails.

In any event, whether a direct reading AoA gauge would have saved AF442 remains to be seen, but when you get right down to it, they broke one basic rule, "Never, ever fly through a thunderstorm!"

How might AOA be implemented in an Airliner
 

Normally, you would be getting particularly useful information from an AOA indicator only during the takeoff roll and acceleration to climb schedule. Once up to solid flying speed (however you wish to define it), the AOA loses most of its utility until you slow back down for landing, for holding or during those moments of stark terror when the aircraft is behaving strangely.
The military AOA indicators I'm familiar with are analog devices that are set so that the 3 o'clock position of the needle is the appropriate approach speed for the aircraft. Needle rotation towards the 2 o'clock position indicates that the aircraft is above target AOA/ below approach speed. Normally during cruise, the needle would be pointed downward toward the 5 o'clock area of the dial.
It is very easy for the eye to pick up the angle of the needle without having to spend much effort scanning it. I would think easier to integrate into your flying than vertical tape displays or (ugh) digital numeric displays.
It would be very easy to stick this kind of info into a relatively open area of the PFD using modern display techniques. You could change colors and flash that part of the display if the aircraft slowed so that the needle was angled above the 3 o'clock position. As aircraft gross weight varied, there would be no need for correction, it is built into the operating principle. On the aircraft I have flown, the AOA indications were valid from flaps up to leading and trailing edge flaps down. If an aircraft needed correction for various flap configurations, it would be easy to use flap position data to adjust the display since the whole display would be synthetic.
A vane/sensor stuck in the high AOA position during the takeoff run would be indicated early on because AOA indication would not be inhibited in the way that stall warning is by the WOW switch. The military sensors I'm familiar with would come alive in a mild breeze.
During cruise, the AOA indication would be inobtrusive but visible. Should the AOA system sense indications are getting out of limits, it would call attention to itself. You would gain familiarity with the system by observing it during a variety of flight regimes and in the simulator.
During takeoff, you would rotate as you customarily do and scan AOA briefly to ensure you haven't over-rotated. (Suppose your airspeed indications were lying). On approach, AOA may bounce around a bit in rough weather, but other than that sinking feeling in the seat of the pants, it is one of the first things to give you quantitative information on how bad that wind shear you are flying into is.
And one final very strong selling point, when all the other air data instruments pack up and play stupid. AOA will keep on doing its job. All it needs is essential buss power..

Normally, you would be getting particularly useful information from an AOA indicator only during the takeoff roll and acceleration to climb schedule. Once up to solid flying speed (however you wish to define it), the AOA loses most of its utility until you slow back down for landing, for holding or during those moments of stark terror when the aircraft is behaving strangely.

Totally wrong. In cruise and stabilised flight, you get from an AOA all sort of useful information (LRC, gliding speed...) Euh, also using the AOA for the take-off phase is something I never heard of...

The military AOA indicators I'm familiar with are analog devices that are set so that the 3 o'clock position of the needle is the appropriate approach speed for the aircraft. Needle rotation towards the 2 o'clock position indicates that the aircraft is above target AOA/ below approach speed. Normally during cruise, the needle would be pointed downward toward the 5 o'clock area of the dial.

Those are AOA from the beginning of the seventies (like the AOA on the RAF Jaguar !!) very poorly designed and cumbersome. The French have been using since the middle of the 70's on all their fighters, a moving tape for the AOA, with colored sectors, which is beautifully easy to understand and therefore to use. Thus also for landings you no longer have to bug the speeds ... but as our distinguished americain colleague said, this is so deeply ingrained in the majority of the brains of our heavy colleagues (that you have to bug the speeds, and that AOA are for jets &"#!??@??) that I'm afraid it's a lost cause.

I'd like to throw out a question as food for thought. IF, and that's a big IF, the aircraft and/or boxes are NOT found what do you think the next step in this process would be?

AoA in Cruise
 

The problem with trying to use AoA at cruise speeds is that AoA varies relatively little with changes in airspeed but at climb out and approach speeds it varies rapidly and instantaneously with pitch. Although I never used it on the roll, in climb out it gives you a rapid means of finding L/Dmax which is needed when you lose an engine. In fact, the procedure for losing an engine off the catapult is to rotate to a specified AoA. You could also use it to find the best glide speed but it would be very sensitive and thus hard to hold at those higher speeds.