Tech Log The very best in practical technical discussion on the web

AF447

Old 2nd Jul 2009, 20:50
  #2741 (permalink)  
 
Join Date: Aug 2006
Location: London
Posts: 51
Likes: 0
Received 0 Likes on 0 Posts
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.
320 driver is offline  
Old 2nd Jul 2009, 20:53
  #2742 (permalink)  
 
Join Date: Jul 2009
Location: This causes prejudice
Posts: 10
Likes: 0
Received 0 Likes on 0 Posts
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?
Grayengineer is offline  
Old 2nd Jul 2009, 20:58
  #2743 (permalink)  
 
Join Date: Jun 2009
Location: Bedford, UK
Age: 70
Posts: 1,328
Likes: 0
Received 0 Likes on 0 Posts
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.
Mr Optimistic is offline  
Old 2nd Jul 2009, 20:58
  #2744 (permalink)  
 
Join Date: Aug 2006
Location: London
Posts: 51
Likes: 0
Received 0 Likes on 0 Posts
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.
320 driver is offline  
Old 2nd Jul 2009, 21:06
  #2745 (permalink)  
 
Join Date: Jun 2009
Location: France
Age: 76
Posts: 196
Likes: 0
Received 1 Like on 1 Post
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.
DJ77 is offline  
Old 2nd Jul 2009, 21:07
  #2746 (permalink)  
 
Join Date: Jun 2009
Location: east of 10 west
Age: 62
Posts: 104
Likes: 0
Received 0 Likes on 0 Posts
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..
falconer1 is offline  
Old 2nd Jul 2009, 21:16
  #2747 (permalink)  
Per Ardua ad Astraeus
 
Join Date: Mar 2000
Location: UK
Posts: 18,579
Likes: 0
Received 0 Likes on 0 Posts
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.
BOAC is offline  
Old 2nd Jul 2009, 21:20
  #2748 (permalink)  
 
Join Date: Jun 2009
Location: Colorado
Age: 74
Posts: 48
Likes: 0
Received 0 Likes on 0 Posts
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?
EGMA is offline  
Old 2nd Jul 2009, 21:22
  #2749 (permalink)  
 
Join Date: Aug 2006
Location: London
Posts: 51
Likes: 0
Received 0 Likes on 0 Posts
It is a sea anchor!
320 driver is offline  
Old 2nd Jul 2009, 21:22
  #2750 (permalink)  
 
Join Date: Mar 2001
Location: us
Posts: 694
Likes: 0
Received 0 Likes on 0 Posts
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 is offline  
Old 2nd Jul 2009, 21:25
  #2751 (permalink)  
 
Join Date: Mar 2001
Location: us
Posts: 694
Likes: 0
Received 0 Likes on 0 Posts
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.
SaturnV is offline  
Old 2nd Jul 2009, 21:26
  #2752 (permalink)  
 
Join Date: Sep 2001
Location: Toronto
Posts: 2,518
Received 14 Likes on 7 Posts
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.
RatherBeFlying is offline  
Old 2nd Jul 2009, 21:27
  #2753 (permalink)  
 
Join Date: Sep 2007
Location: Germany
Posts: 152
Likes: 0
Received 0 Likes on 0 Posts
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 ?
OleOle is offline  
Old 2nd Jul 2009, 21:31
  #2754 (permalink)  
 
Join Date: Jun 2009
Location: east of 10 west
Age: 62
Posts: 104
Likes: 0
Received 0 Likes on 0 Posts
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..
falconer1 is offline  
Old 2nd Jul 2009, 21:36
  #2755 (permalink)  
 
Join Date: Jul 2009
Location: This causes prejudice
Posts: 10
Likes: 0
Received 0 Likes on 0 Posts
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?
Grayengineer is offline  
Old 2nd Jul 2009, 21:40
  #2756 (permalink)  
 
Join Date: Jun 2009
Location: Colorado
Posts: 41
Likes: 0
Received 0 Likes on 0 Posts
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.
ttcse is offline  
Old 2nd Jul 2009, 21:43
  #2757 (permalink)  
 
Join Date: Jun 2009
Location: ATL
Age: 66
Posts: 131
Likes: 0
Received 0 Likes on 0 Posts
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.
ClippedCub is offline  
Old 2nd Jul 2009, 21:50
  #2758 (permalink)  
 
Join Date: Jun 2008
Location: Europe
Posts: 136
Likes: 0
Received 0 Likes on 0 Posts
BEA report

I am impressed by the depth of analysis already communicated in the BEA report issued today.
daikilo is offline  
Old 2nd Jul 2009, 21:50
  #2759 (permalink)  
 
Join Date: Jan 2002
Location: USA
Posts: 286
Likes: 0
Received 0 Likes on 0 Posts
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.
wes_wall is offline  
Old 2nd Jul 2009, 21:51
  #2760 (permalink)  
 
Join Date: Jul 2009
Location: This causes prejudice
Posts: 10
Likes: 0
Received 0 Likes on 0 Posts
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.
Grayengineer is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.