forget;
Exactly my point.

Grass tracks
 

I agree that there's plenty of information to be gained from the tracks;
however, remember that the low-resolution photo taken from a single,
shallow angle that is fueling the current discussion (e.g as shown in 1034)
gives only a tiny fraction of the available information.

The investigators will have a great deal more information from walking the
ground, by measuring the width/depth of the gouges, finding debris and
scrape marks along and alongside the tracks, and seeing which features
are lower and which higher.

XPMorten reasonably convinces me that the light curved marks following
the main gear tracks are from a car, and may be much tougher to make
out in a non-foreshortened photo. Driving over the evidence might not
have been the best plan in hindsight, but remember that the ground is
probably very hard, having been baked for most of the Madrid summer,
and so the effects are probably slight. The hard ground also means that
any inferences that grow out of experience of tracks made on a nice, green
field could be severely awry. I suspect that any visible gouge in this
ground reflects a very violent impact/ploughing action.

(My background is just as frequent SLF, but as an astrophysicist :8 I have
experience of dynamics and (over-?)interpreting faint hints in inadequate
images.

Back to an earlier subthread, I would very much regret losing the chance to
follow discussions on these forums for not being a pro - I have used examples
informed by your collective discussions many times in undergrad classes.)

In fairness to those involved on-scene, any vehicle tracks could well have been made before the accident. Unlikely; but possible.

Apologies if this is the dumbest of dumb suggestions, but is there any possibility that the straight track, which we're speculating might have been made by the nose gear, could actually have been made by the tail?

It looks as if the track starts at a point roughly level with the tail cone, and it's parallel to the eventual track of the main gear, as if the tail hit just as the aircraft was steering to port. Is it possible that this was the tail strike that's been mentioned?

Of course, the track is well off-centre, which suggest that I'm wildly wrong, or the tail section had partly broken off by that point and was dragging on the left, or perhaps was subject to that weird geometry we've been looking at.

And given the foreshortened perspective, it could be that my theory makes the plane half a mile long! It's just an idea.

I don´t think that this is possible. The tail is a lot closer to the main gear, so the plane would have to drift a LOT more than if it had been the nose wheel (what we also don´t know for sure). So the 7° mentioned before for the nose wheel would be some 30°-40° for the tail (just a wild guess), which would bring the main gear tracks closer together.

I tend to think that the straight line stems from the nose wheel, what is not completely consistent with that however is, that a drift of the airframe should bring the main wheel tracks closer together (which might be lost in the angle of the photo).

Jacilore, I think your diagram is wrong. The well-defined triangle is made by all the gear hitting the ground at the start of the three heavy black lines, the skid marks.

The straight black line is the nosewheel and the two twin curving skid marks are the main gear. The nosewheel track is straight and the main gear drifts first left and then right.

See xkoote’s illustration in Post 1023.

There are several rows of tracks parallel to the runway -- likely a tractor pulling a mower.

And other tracks indicative of the tractor coming back to resume where it had left off.

The nosewheel while attached will likely leave a track less distinct that that from a tractor.

207 kph & Inop Reverser
 

Telecinco reports the investigation is centering on why the aircraft failed to reach the necessary 210 kph for takeoff, reaching only 207 kph. The recovered deployed reverser was activated by the pilot, but the right side reverser could not be deployed as it had been deactivated since August 17. The pilot attempted to brake using the pedals and deployed reverse thrust.

-------------

27.08.08 | 15:11 h. INFORMATIVOS TELECINCO

Según la última línea de investigación, el avión no alcanzó la velocidad necesaria para elevarse. La aeronave no llegó a despegar al no acelerar lo suficiente y terminó dando tumbos por la pista. La comisión de investigación centra todos sus esfuerzos en determinar por qué la velocidad no llegó a los 210 kilómetros por hora necesarios para despegar y se quedó en los 207 kilómetros. Informativos Telecinco también ha podido saber que la reversa derecha del avión estaba bloqueada desde el día 17 de agosto.

El MD- 82 recorrió la pista con aparente normalidad pero no alcanzó la velocidad necesaria para despegar. A unos metros de la pista se aprecia en la fotografía el cono de la cola entre otras piezas del avión. Una parte del motor también se desprendió en el intento de despegue.

Una de las piezas encontradas tras el siniestro fue una reversa desplegada. Ese freno fue activado por el piloto, pero la reversa derecha no pudo ser desplegada por un fallo registrado en una revisión habitual el día 17 de agosto que había impedido activarla, por lo que fue bloqueada ese mismo día. Según la normativa vigente, un avión puede volar de forma normal sólo con una reversa y si otra es bloqueada, puede hacerlo durante diez días (habría estado permitido hasta el día 27 de agosto).

Según ha podido saber Informativos Telecinco, la Comisión de investigación centra sus esfuerzos en determinar por qué el avión no alcanzó la velocidad adecuada. El piloto intentó frenar con los pedales y luego con las reversas.

Catplaystation (and others)

It's human nature to be curious. Otherwise we would never learn anything new. Man would never have invented the aircraft.
I suspect a majority of "speculators" here have technical backgrounds.
We are educated to solve technical problems given to us whatever facts we are
presented with. Speculations and theory's are part of the learning process and
isolating the problem. Call it brain exercise, it's healthy - even to pilots - ask your doctor :ok:

XPM

Weight of aircraft approx 60 tonne, if equal weight on all three axles
Axle weight 60/3 = 20 tonne

Weight of tractor possibly 2 tonne
Axle weight 2/2 =1 tonne

So a possible 20 (10 tonne per wheel) tonne weight will leave less distinct mark than 1 tonne (1/2 tonne per wheel)?

I accept that the weight balance of an aircraft will lead to differing weights to the above but cannot accept that the nose wheels would have a low figure (otherwise the nose would be bouncing into the air)

The MD80 on average has about 7% of it's total weight on the nosegear.
So, 4,2T on the nose.

XPM

One more question to pilots of similar airplanes. Assuming a fairly normal looking take-off, but one that took some "500m more than usual" to be accomplished like reported (we are unsure if fully on the ground or extra long rotation)...

Is this compatible with assymetrical accidental reverser deployment?

-If such thing happened say right after or inmediately before V2, it wouldn't explain the long time it took to (theoretically) accelerate on the ground to reach V2, right?

-If such thing happened after V1 (so crew had to choose the option to continue) but before VR (or around at that time), wouldn't normally the crew had realised something was seriously wrong and either try to abort or have time to compensate (given the long runaway) plus wouldn't the airplane tend to move left or right while still on the ground, or not necessarily? Also, would the survivors or the crew notice clearly some sudden decceleration or forces to one side necessarily, or not? Would they notice something incompatible with "normal feeling take-off, going up, some vibration, rolling to one side, rolling steeply to the other, crashing"?

Thanks.

Another survivor has left the hospital. 14 remain. 2 remain in very serious condition.

Accidental thrust reverser deployment now ruled out
Thrust setting not sufficient. Again, pulled RAM probe heater CB part of the picture?

210 kph is only 113 kts. That is certainly not the required VR or V2. Somebody may have mixed up knots and miles when converting?

Could it be possible that the pilot selected reverse after the a/c was back on the ground in an attempt to stop? would be a logical explanation to find the reverser out of stowed position in the wreckage......

Could it be a deep stall due to a flap 0 TO?

m73k if you read the post above yours it will tell you about the reverse thruster and why only one was found locked

justme69 errr.... abort after V1 :=

It is of course possible that a crew might elect to abort after V1, however, it would be such an exceptional circumstance or error that I do not think it worth speculating on without concrete evidence that it occurred :oh:

NoD

thank you theron, been wandering about that when the first stories about the thrust reverser popped up...... the answer posted 9 minutes earlier.. hope the answers from the fdr and cvr will shed a light on what did happen... anybody info of the type of fdr/cvr installed in md82 a/c (digital/analoge, amount of parameters monitored etc.)?

Telecinco groundtrack photo for Google Earth processed
 

I have compensated the Telecinco photo of the groundtracks for perspective. The processing assumes a flat terrain.

Google Earth Community: Spanair flight JK 5022 accident in Madrid

I can be viewed in Google Earth (recommended) or Google Maps. Some resolution was lost in the process of creating the KMZ file.

Why on earth would anyone be calculating take off speeds in KPH?