Dand07, your post is grammatically and syntactically incorrect, then once one manages to read (interpret ?) it, you're insinuating a certain vested interest by pprune members that is neither clear nor likely.
Please refrain from wasting your and our time writing "under the influence" in the future.

Nicolai, not sure if you read this thread in full, but we're being given an update about survivors conditions few hours ago from someone citing spanish sources, by logic these should be more current than BBC, so in this case the sacred broadcaster is of no help.

el #,
I've (re)read the whole thing and I didn't see anyone posting an update from any other source as to this (significant) change in status of casualties so I thought to put it up as a new piece of info, and I merely said "the BBC" to state my source; it's not a Spanish source because my Spanish isn't very good.
In this sort of news story, who gets the word out first can vary more with whether or not someone's sub-editor is on a teabreak :E rather than who has the info first, since the news will travel very fast.

SLATS: 777fly, dash-27 et al
 

The configuration of the Slats (and flaps) will be a basic part of the initial investigation to verify. The system is well decribed in the MD-80 LAMM Section 27-85-00 page 101-103, including the auto slat behavior and warning systems.

• The Slat position is recorded to DFDR/QAR via the DFDAU
• The cables may have witness marks to indicate position when tensile loads may cause separation of the cable
• The actuator will indicate the position of the Slat drive drum (27-81-1), as will the autoslat actuator MI 76/77 etc. As well, the Flap/Slat handle position will be identifiable

.

quote reports unquote of possible lateral instability will certainly ensure some investigation is conducted in this area by competent investigating authorities.

As to CAWS: the 28v DC -L CB would need to be tripped, B1-832, AND the 28V DC-R CB B1-851 would need to be tripped for the crew to NOT get a warning of the CAWS being degraded/failed. (LAMM 31-51-00)

CVR will be interesting.

Nicolai, look at posts by 'justme69', #685 and #694.
I do not want to diminuish your contribution, but it's just that as you said, news circulate fast and someone invariably will report to pprune with expeditiousness.

(apologies if it has already been posted)

Survivor describes wobble, crash, painful aftermath - CNN.com

"The airliner that crashed this week in Madrid had just barely got airborne and its right wing dipped sharply before the plane started wobbling and went down, one of the few survivors of the disaster said Saturday.
...
"But then it made a turn, as if the wing dropped abruptly," she said. "We were still very low, very close to the ground."
After the plane got a bit higher, it began to "wobble from side to side," she said, describing this as the last thing she remembers before the collision."

It seems at some point politicians were advised by two pilots "experts" who were allowed to watch the tape. A reporter writes about one of them saying: "It had to be a chain of errors ... a miriad of factors such as wind, bad cargo distribution or some external element such a large bird or a bad reaction from the pilots"

This expert is very puzzled that the plane (in the words of the reporter) "fell to the right when it would've been normal to fall to the left if the left engine was damaged" (as originally rumoured ... I don't know who came out with that rumor to begin with ...)

Both experts agree that it was very unlikely that the earlier fault that prompted the return to gate had anything significant to do with the direct cause of the accident.

But one of the two experts (I'm quoting the reporter now) "insisted that the accident could have originated due to an excess of weight in the plane and cited that as the most likely cause".

Ground airport personel at Spanair Barajas think that it's unlikely the airplane was grossly overloaded, but it was likely indeed either full, close to full or slightly over full capacity.

Once more, it's not fully clear how the airplane "fell" shortly after wheels left the ground. Seems it rolled a bit and fell, with one wing briefly touching the ground. Obviously at over max landing weight it could've sustained some damage from the "fall" and possibly injure pilots as well and start fires, etc.

My take on things: The plane was fully loaded, perhaps a bit over specs (but not necessarily). Some configuration was off-mark (either flaps or, more likely, slats). Enviromental conditions were not too good for sustenability (low air density, little but significant tail wind). Vr calculation was probably a bit short. Pilots unadvertenly used up a bit more runaway than usual without realizing something was off and then tried to take off a bit abruptly (your usual "if you want to go up, pull the wheel towards you"). For reasons unkown the plane stalled soon after ground effect was over w/o the pilots taking inmediate correction measures (perhaps they didn't have time as it rolled a bit much during stall for unknown reasons) or the engines failing to produce enough thrust and the plane hit the ground bouncing around for a while (perhaps accelerating after additional thrust was demanded a bit too late trying to complete take-off) sustaining damage (wing touching ground, landing gear over max. landing weight) or pilot injuries that led to lack of control, perhaps a decission to try to brake, and made it ultimately deviate to the right of the landing strip (wing hitting the ground damage could've produced assymetrical aileron configuration) and onto adjacent terrain where it finally crashed at high speed.

The plane rolling while airbone a bit too much could also be due to an assymetrical thrust situation (single engine failure or assymetrical reverser deployment, i.e.) rather than a random product of the stall in low density air or pilot action.

All of that, pure and baseless speculation of what could've happenned, but it's the mental picture I came out with while reading all the news about it here, in Spain. No idea how that could've happened, but it is what we've ambiguously been told by the media that happened so far.

This baffles me completely.....
 

This accident has left me for a loss for words. Here's why.

- If the RAT Probe heater fails in the ON position no light will illuminate in the cockpit. What did the captain mean?

- A RAt with an INOP heater and released due to favourable weather conditions is the same condition and terminlgy stated in it's MEL. So we'll take the mech for his word that the heater crapped out. In this case, especially on 29 degree Wx, no effect will be noticed and temps read correctly.

- Airplane stuck in air mode, with the plane not configure for takeoff? Could be, but then how can a pretty stiffly loaded MD82 roll dor takeoff, become airborne then crash back down all in less than a runways' length?
For an MD80 to become airborne with no slats in that condition requires at least 200 knots. Otherwise it will not fly, period. Maybe flaps less than prescribed? Should make that much difference if the slats are in the correct position.

- As I already said. If the plane had a problem being in airborne mode, MOST likely they can not retract the landing gear! This coupled with an engine failure MAY convence the crew to try and abort the TO. Maybe even as desperate as to deploy reverser as quickly as possible.

This scenario is all I can come up with. Many thoeries do not add up given the distance it travelled from brakes release for final resting place.


Xander

Possibly Related (or a premmy flap/slat retraction in lieu of gear?)
 

At 0938 Central Standard Time on 2 August 2006, a Boeing Company 717-200 aircraft, registered VH-NXE, took off from Alice Springs Airport, NT, on a scheduled flight to Perth, WA.

The applicable aircraft take-off settings and techniques were applied by the flight crew for the takeoff. The recorded data showed that, 4 seconds after lift off, when about 31 ft above the runway, the aircraft's stall warning system activated for 4 seconds, and that the aircraft did not approach an aerodynamic stall condition at any time during the stick shaker activation. In response to the activation of the stick shaker, the flight crew increased engine thrust and reduced the aircraft's pitch attitude.

It is almost certain that an incorrect left wing slat sensor signal was received by the proximity sensing electronics unit (PSEU) from one of the two left wing slats proximity sensors. Consequently, the different slat position signals from the two sensors in the left wing resulted in the PSEU defaulting to the slats not-extended indication for the left wing. As a result of the different slat position signals sent by the proximity sensing electronics unit for the left wing (slats not-extended) and right wing (slats extended), the aircraft's flight control computers used the flaps-extended/slats-retracted stick shaker angle of attack schedule, leading to stick shaker activation and other stall indications.

Although no explanation could be found for the incorrect signal received by the PSEU from one of the two left wing slats proximity sensors, the aircraft manufacturer concluded that there did not appear to be a systemic problem in the worldwide 717 fleet.

Download complete report [508 KB PDF]

Premature flap (in lieu of gear) retraction. REPORT

The Crash of Northwest Airlines Flight 255 (MD82) at Detroit Metro - REPORT

Loose rivets - apologies. The only part of post 507 where I was addressing you was the first paragraph. At the time there was a whole load of posts - since deleted - making major suppositions, and the rest of that post was addressed to them. Sorry, I should have made it clearer.

I find it in bad taste to be nit-picking - in what is basically a technical discussion - about how many died, how many have been identified, and how many survivors are succumbing to their injurues or fighting for their lives, and who is right and who is wrong. Is this an ego contest ?

Unless you had a friend or relative on board - in which case you will be getting personal updates - what does it matter to anyone else ? It is sufficient to accept that this is a major disaster, with massive loss of life and in due course the correct figures will pass into historical statistics. QED.

Leave it alone.

Rewrote post 708 (in order to try and understand its ramifications)
 

ref the return to the ramp......

In the MD-82, the RAT probe sends temp data into the Air Data Computers.This data, in digital format, feeds both digital flight guidance computers.The DFGCs compute the EPR for each flight phase and for pilot selection through the TRP (thrust rating panel).The RAT probe is heated only in flight for anti-ice purpose. If, for some reason, the ground/air sensing relays (energized on the ground) change to an inflight condition, the RAT sensor is heated and the EPR is reduced. This change may be due to a circuit breaker opening (or a ground/flight sensor relay CB being left open by the mech after he deactivated the system? - shades of Helios?) or a ground/air sensor relay failing .This condition may affect the takeoff condition warning too. None of these prospective developments would be evident to the pilots.
.
The ART (automatic reserve thrust) is used only in normal T/O EPR. i.e. not in flex. or max. It's activated when the DFGC senses a difference of 30% between both N1 gauges. It's not an autothrottle function but carried out inside the fuel control unit. Its effective increase is about 700 lbs thrust or .05 EPR to the present thrust. The ATR ( auto thrust restoration) with the last DFGCs (-972 and subsequent ) is only active in noise reduction cutback procedures.

Crashed plane's safety licence 'due to expire'
 

Dear Edward Owen "in Madrid" for the Telegraph,

may I suggest you refrain from writing about any technical issues to do with the accident. Putting your name to rubbish like this:
does nothing but add to confusion and display the ignorance of you and your editor.

I cant understand why everyone is so puzzled about the roll off to the right. A classic manifestation of an incipient stall in ground effect and at high angles of attack is a kind of dutch roll (its not dutch roll). That means that the a/c would not be pointing along the centreline when it re-contacted the ground.

The "shuddering and side to side" motion described by survivors in Madrid is entirely consistent with a stall at high angle of attack and is identical to that described by survivors (or decryption of FDR tapes where there were no survivors) in MANY previous incidents. Sevenstrokeroll mentioned Detroit (DC-9-80, T/O configuration annunciator disabled, crew distraction, flaps/slats not set).

The yaw/roll degrades already insufficient lift (i've read by about 20%). The a/c just happened to be on a r/h yaw/roll when it returned to earth. If it had been on a l/h roll the survivability may have been very different.

Pinkman

how many meters/feet after the power application the Md80 should have rotate?
Does the pilot refer only to VR to rotate or should he/she have an approximate landmark for the rotation point? (I guess Yes)
My modest theory is that if the pilots did not RTO is because they were underpowered hoping to be able to get airborne anyway since the runway was so long.
then a combination of density altitude and faulty (perhaps) EPR temp air data made such tragic cocktail .

what do you think?

then: "two decades of fear" Since I was flying the 737-100 I was always afraid of un-commanded deployment in flight. is in that old reverser design the Clamshell kept closed by sort of springs? if there is not hydraulic pressure could a reverser fall open by the air stream (is like a metallic parachute). Many Biz jet still use this old clamshell design..

One thing that makes me wonder is if this aircraft did stall for whatever reason did the crew at any time attempt to get full thrust?

I wonder because after looking at accident details of the 73 going into the Potomac I always wondered at the time why no-one firewalled the thrust levers. It clearly wasn't flying so why not slam the thrust levers to the wall? This has always made me wonder that if as operating crews we lose something after sitting on a modern jet for many hours.

Obviously after V1 no-one has their hands on the thrust levers and hands don't go back on them till after rotation and climbing away. I remember early in my training on Jets being told by a trainer that I was putting my hands back on the thrust levers too soon after rotation. I was told there was no need to put them on so early, it wasn't required. I remember thinking - what if I need extra thrust??? What if the thing doesn't fly? Does this breed a mindset to leave the thrust levers alone?
However, a while back my company as part of the recurrent sim check did a V1 cut at a hot and high airfield. Several knot split on V1 and Vr and unless you toga'd the thrust levers the thing really didn't want to fly. Sounds like everyone did firewall it.
Also whenever we seem to run windshear stuff, particularly soon after rotation people do toga it. Is this because we make the connection - eng fail - need thrust. Windshear - need thrust. But what happens outside of these cases where you aren't getting flashing lights and bells but the thing isn't flying??

Can't help but wonder if you find yourself in a very unusual situation as these chaps did. Not seeming right but you aren't sure as nothing is clearly wrong, realise little too late that its taking way too long to get to speed, you are eating up runway, thing not getting airborne then stalling - you are going to be stressed and maxed out. As capacity shrinks do you have the capacity to think "f*ck me - firewall the donkeys" or do you grip the control column with both hands fighting it into the air?

I am not by any means saying keep hands on after V1 as we all know exactly why we do that. This event being extremely rare it would never justify it but do you think we do possibly lose that connection between struggling to fly (at very early stage after rotation etc) and slapping some extra thrust on?
This could potentially now be 2 cases where application of extra thrust may have saved the day. Unless of course these guys did do that and it still didn't fly!?!?

Guys that have been on jets for a while, what do you think? Do you think we do lose that instinctive connection or not? Particularly when maxed out due to a VERY abnormal situation? I would personally like to think not but.....

In no way thinking this is cause or contributing factor but this accident has made me wonder. Might be thread creep (might however be relevant) but do you think that unless it falls into a nice pigeon hole failure some crews may not realise in enough time that they need extra thrust? Sorry actually not working on a Sunday seems to have got my mind wandering!!

I'm not a TRI/TRE so don't see many people in the sim, be interesting to hear from you guys what you think as you see a lot of crews doing this stuff.

Actually, No. I'm not aware of any civil operator using physical length of runway to measure if the acceleration is normal, this would need marker boards on every runway, and take-off calculations would have to relate speed to distance for every runway used - possible but not really practical, tho' I believe the RAF did this at some of their airfields - don't quote or shoot me, don't know for sure.

The critical speed is V1, after that there is insufficient length to stop in the remaining length of concrete, and it would be very difficult to judge - if the acceleration felt sluggish - whether to accept the overrun or haul it into the air at the last minute and hope for the best.

My reading of this situation is that there was apparently plenty of runway left after rotation, which would indicate that the crew thought that they had reached VR - rotation speed - and had attemped to get airborne, otherwise they would have held it down as long as possible, or even run off straight ahead, which doesn't gel with the suggestion that they might have been airborne too slowly and stalled - why would they pull it off if there was a lot of runway left, unless they thought they were at the right VR speed ? Which then begs the question - why didn't it accelerate to V2 - if that in fact happened ?

Still a long way to go, we will just have to be patient.

Whilst writing this I missed the post of OnePostOnly, and can accept that his hypothesis has some merit, except that I still feel that they must have reached VR, and started to fly, the question then is why didn't the acceleration to V2 continue, or when leaving ground effect, with some problem that they weren't aware of, even a mistake in computing V speeds maybe, OnePostOnly's theory then took over ? :confused:

Xcoote,

Your ignorance of aircraft handling techniques, aerodynamics and mechanics indicates that you cannot be a commercial pilot, surely?

I have no experience of MD80 operation, but if the free air stall speed is 200kts, it will fly at speeds well below that figure while in ground effect.

For other posters, ground effect has nothing to do with air density.

Some MD80 stall numbers.
At high gross weights, there is a penalty of around 30 kias
on stall speed not having slats deployed.

XPM

http://www.xplanefreeware.net/morten/DOCS/mdstall.jpg

XPMorten:

Thanks for the graph. From that I deduce that at max weight, the crew would be looking for a flap 15 climb speed of about V2+10, or about 165 kts, after rotation? The slat retracted stall speed is given as 172kts. The aircraft would certainly have been able to fly in ground effect, with a clean wing, with that small margin.

Many of these posts show the degree to which Anglophones are hampered in trying to understand a situation where so much of the available information is in another language.
"Justme69" has commented on the amount of runway used by the aircraft. A friend told me yesterday that El Pais reported that the aircraft used all the runway. This was, I think, reported to the press by the head of the autonomous government in the Canaries. My friend's Spanish is very good (much better than mine) but obviously care needs to be exercised here over the translation. Is there anyone who is bilingual able to comment on this? I don't think I've read elsewhere on this thread that the aircraft used all the runway (could have missed it, though).
P.S. Apparently, El Pais also reported that the wind direction changed shortly before the attempted take off and that the Spanair aircraft attempted its take off with a tail wind. There seems to have been a comment from flight deck crew of another aircraft (taking off, landing or moving on the ground at Barajas) about this.