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-   -   AF447 (https://www.pprune.org/tech-log/376433-af447.html)

320 driver 2nd Jul 2009 19:50

To the SLF:

Generally, one would obtain approval for a deviation. However, if the need becomes critical, ATC comms are poor, or one is in an uncongested area then it is, in my opinion, better to analyse the risk and deviate anyway if necessary. With modern TCAS systems the risk of conflicting with other traffic are greatly reduced.

Grayengineer 2nd Jul 2009 19:53

DB - Concur - some forward speed, but not a lot or damage to vertical structures would have occurred and high vertical downward velocity. Flat bottom impact with sea seems to fit. Does a stall at low altitude (Amsterdam crash) seem to fit facts?

Mr Optimistic 2nd Jul 2009 19:58

VS
 
VS damage surely strongly points to it not being completely separated in flight (such that it would surely have slammed into the ocean on its own at high speed at arbitrary angle), that it was still attached to some structure with more mass/inertia than itself, that it was still pointing upwards-ish at impact, and that there was forward speed.

320 driver 2nd Jul 2009 19:58

I don't think you can usefully read anything into the 200km spread regarding the integrity of the airframe. As Lockerbie and other accidents have demonstrated, a break sudden break up at cruise would only contribute a maximum of 10-20km worth of spread. This figure is not significant compared to the spread seen here which must therefore be attributed to other factors such as ocean currents.

DJ77 2nd Jul 2009 20:06

From Blue Amber:


Contracts are INITIATED BY THE GROUND and CAN NOT be modified by the pilot
But before ATC can contract anything, the crew has to manually logon to the ADS / CPDLC system. This is what the AF447 crew attempted to do three times as reported by the BEA, so they where were not incapacitated at 0201.

falconer1 2nd Jul 2009 20:07

absolutely right 320 driver
 

Generally, one would obtain approval for a deviation. However, if the need becomes critical, ATC comms are poor, or one is in an uncongested area then it is, in my opinion, better to analyse the risk and deviate anyway if necessary. With modern TCAS systems the risk of conflicting with other traffic are greatly reduced.
I would add though, you wrote that very diplomatically..

it is not only better to deviate without clearance, it is an absolute "MUST", the rules of the air stipulate that a pilot in command, being responsible for all that is happening is "REQUIRED" to deviate from "rules of the air", in this case from obtaining a clearance, if the safety of flight requires immediate action..

so, out there, in the boonies, where the folks at receiving end of the HF may have gone out for lunch, maybe not even having my flight plan, because somebody forgot to add the AFTN address of their FIR, hell, I would not wait any second for some "deviation clearance" or some rerouting, I'd always deviate first, whichever direction I would deem fit, knowing that any potentially conflicting traffic , like me, also is equipped with TCAS II, and I would see any traffic problem on my TCAS either as a TA or ultimately as an RA..

I suspect however that some folks nowadays wait too long in such situations for "reclearances" and may by that fact alone end up in some very difficult situations..

that should be addressed in training nowadays..

BOAC 2nd Jul 2009 20:16

People seem to be forgetting that it is 'good practice' to broadcast your intentions/actions in Oceanic airspace due to the possibly adjacent track traffic. No such call appears to have been made, unless everyone was asleep.

EGMA 2nd Jul 2009 20:20

Yes, we don't have all the facts and yes surface currents would be a factor, although I seem to remember from an earlier posting the the surface currents showed a different track to the debris field.

Yes the VS may be the first item to detach on impact with the ocean. My question would be; why is it the first item in a 100 km long debris field, was it fitted with a sea anchor?

320 driver 2nd Jul 2009 20:22

It is a sea anchor!

SaturnV 2nd Jul 2009 20:22

takata, the IB and AF flights following AF447 reported repeated difficulty in contacting Dakar. I understood the three queries to Dakar ADS-C between 1:33 and 2:01 to be automated.

AF459

On leaving the ATLANTICO FIR, through the TASIL waypoint, the crew attempted in vain to contact Dakar control in HF on the 5565 KHz and 6535 KHz frequencies, and on the other HF frequencies given in the on-board documentation. Likewise, the attempted ADS-C connection was unfruitful.
The crew returned to the airway around the ASEBA waypoint, that is to say more than 28 minutes after the first theoretical contact.

SaturnV 2nd Jul 2009 20:25

EGMA, there is nothing that I have seen in the published record that indicates the VS was the first item recovered. There was a recovery position (lat and long) for the VS posted in another forum, but that was unofficial.

RatherBeFlying 2nd Jul 2009 20:26

Deep Stall
 
Deep stall accidents commonly include flameouts and atypically low airspeeds. There is a possibility these low airspeeds triggered "pitot failure" messages.

The underlying idea behind rough air penetration speeds is that you will stall before the airframe breaks. Perhaps we have seen a stall that was unrecoverable in the circumstances.

OleOle 2nd Jul 2009 20:27

The Amsterdam Crash had a number of uninjured survivors. It seems there havn't been any in this crash, so a significant higher energie must have been involved.

A few days back, it was discussed in this thread, that deducing from the distribution of debris and the prevailing currents the a/c didn't seem to have made much headway towards TASIL after 2:10. Where did all the forward momentum and the potential energy go ?

falconer1 2nd Jul 2009 20:31

the basic procedures for
 
weather avoidance in oceanic airspace, and what to do if no reclearance possible for whatever reason..

http://www.faa.gov/pilots/intl/ocean..._proc_land.pdf

and again, if you find yourself for whatever reason, technical or operational too close to any ugly weather out there, you just deviate, and worry about all the other stuff when you are out of danger..

period..

Grayengineer 2nd Jul 2009 20:36

NTSB will be able to determine the altitude of the drop by the damage. Estimating altitude over water at night is dangerous, I don't fly but as a paratrooper we lost men who got out of their harnesses too soon and dropped hundreds of feet to their deaths - if there were not working altimeters or faulty ones they may have got surprised and thought they were in imminent impact with the sea and did a hard nose up creating a deep stall. Just throwing this out. Fit facts?

ttcse 2nd Jul 2009 20:40

Greyengineer

NSTB will be able to determine the altitude of the drop by the damage. Estimating altitude over water at night is dangerous,
You might be following the thought that af447 stalled at the last moments. 'Concensus chatter by forum posters' would seem to be, if it stalled, it started at high altitude and probably stayed in that flight mode.

ClippedCub 2nd Jul 2009 20:43


I don't know how you can speculate on the failure mode of the VS
The vs didn't fail, the afterbody failed around it - you can see bits of the afterbody attached.

They should have the analysis of reversing wind/sea currents to pinpoint everthing to ground zero by now. To make the suggestion the airplane was intact without the analysis seems premature. Supporting indication of a complete airplane would be detailed evidence that all structure from front to back failed in the same direction. Didn't see any of that in the English version. Also, the recovered bodies would have severe spinal injuries, only remember arms and legs broken.

daikilo 2nd Jul 2009 20:50

BEA report
 
I am impressed by the depth of analysis already communicated in the BEA report issued today.

wes_wall 2nd Jul 2009 20:50

clipped


Also, the recovered bodies would have severe spinal injuries, only remember arms and legs broken.
How do you know this? Nothing has been released vis vis the injuries of the recovered victims.

Grayengineer 2nd Jul 2009 20:51

ttcse - The altitude that this a/c fell from is not from cruise - if it's final stall was there she would have i feel broken apart on decent. This stall i really feel was at low altitude as if they were still flying and maybe looking to ditch. There is no evidence that they were not trying to ditch and this impact type certainly points to a possiblity. Large waves with whitecaps can look like small waves with white caps so you can't tell your altitude - if you guessed the wrong wave height you'll guess the wrong altitude. If you had no engines you would be very cautious.


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