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Incident at Airport Dortmund (Germany)

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Incident at Airport Dortmund (Germany)

Old 5th Jan 2010, 07:55
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I found the Dortmund runwy length :

Takeoff Distance6759 feet
2060 meters

Given their destination they couldn't have had a lot of margin given the weather.
Tough decision to make in that case. Me from my comfy armchair would have continued............ .
This said, the aircraft looks in pretty good shape meaning they couldn't have aborted at a very high speed.
I wouldn't bet my salary on breaking performances with this kind of weather. Looks good on the charts, different in real life.
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Old 5th Jan 2010, 11:00
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This said, the aircraft looks in pretty good shape meaning they couldn't have aborted at a very high speed.
Well they didn't go off the end at high speed thats for sure however looking at the video (allegedly from the flight in question) I would say that the RTO must have been close to V1. With a short, contaminated runway the V1 would have been quite low and with TOGA power set it doesn't take long to get there.
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Old 5th Jan 2010, 11:13
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My personal take-off brief runs something like:

"Config, Warning or Caution below 80 knots I will stop. Between 80 knots and V1 I will stop for Engine Fire, Failure, Loss of Directional control or if the aircraft is un-flyable .... "

If the "80 knots" call comes, and I am indicating something less I would stop.

So, if there is no "80 knots" call from the other side, I call the speed I see:
"85 knots!"

If there is no response I will stop, due suspected crew incapacitation. (I would consider this as a stop for a caution below 80 knots, even though the speed is a bit above - it's recognising the problem below 80 knots and acting within a reasonable limit which counts.)

If the speed call came back as "er ... I've got 70" I now have two choices:
  1. Call stop immediately, which I would probably do if the response was quick enough.
  2. Glance at the standby, and if it agrees with my ASI, call something like "100 knots - Continue!", which I would do if all this had taken us to 100 or so or faster.
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Old 5th Jan 2010, 11:13
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Post 37 - cabin video.

I think this is the video from this flight and rejected take off.

Very interesting to see when the engines spool up how the snow on top of the cowling is sucked in until the relative wind is fast enough to blow it backwards.

Watching the countdown clock - I see the reject seems to have started at 27 sec. after the pilot selected TOGA with the sound of the engines spooling down.

At the 45+ sec. mark (almost 20 sec. after the thrust levers were moved to Idle), the view shifts down and one does not see the reversers deployed yet.

Then near the 50 sec. mark the view is blocked by snow and slush - this is maybe when the reversers have been deployed at very low ground speeds.

A 25+ sec. take off run has accelerate to well past 80 kts, so a reject close to after V1 which must have been with reduced by at least 8-12 kts for wet/contaminated.
Reverse thrust selected too late and thus maybe even the Speed Brakes extended too late after the thrust levers were brought to Idle.
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Old 5th Jan 2010, 11:26
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At the 45+ sec. mark (almost 20 sec. after the thrust levers were moved to Idle), the view shifts down and one does not see the reversers deployed yet.
You can't see the reverser sleeves because of the angle.

Then near the 50 sec. mark the view is blocked by snow and slush
That isn't snow and slush. That is de-icing fluid (you can tell by the way the glycol shears). You can see it reverse flow around 40 seconds - indicating the reversers are deployed and producing reverse thrust.
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Old 5th Jan 2010, 12:12
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Reversers? Relevance at all?
I would care about the brakes and the tires after an abort. They bring the aircraft to a stop.
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Old 5th Jan 2010, 13:57
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Originally Posted by TWOTBAGS:
The Crew did an outstanding job.! In positively CRAP conditions, Dark, slush, snow, shortish runway and long sector (= high weight).
What was so 'outstanding' about it?

Originally Posted by TWOTBAGS:
Having just watched the RTL an bord video the crew did exactly as per SOP.
I probably watched a different video, didn't see or hear the cabin crew doing anything.
Just saw an aircraft aborting after approx. 27sec. after they started their takeoff run.
If it was indeed because of an ASI disagreement I would consider it as a wrong decision.
Those flying the 737 have been trained to cope with unreliable airspeed.
With fuel for DTM-LPA they could have landed at an airport with long rwy and VMC conditions.
As far as I know an ASI disagree is not on Boeings little list with reasons for aborting a takeoff at >80kts speeds.
Is it AB SOP maybe?

Lets wait for the official results of the investigation...
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Old 5th Jan 2010, 20:14
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LYKA wrote..
Engine cowls aren't defined as critical surfaces in the Airbus FCOM. I wouldn't be too concerned over that aspect.
Except that it was a 737. Did you notice how much snow was sucked into the intake when T/O thrust was applied? I would never go flying with that much snow on the cowling.
Re that A320 FCOM - any lawyer would easily convince a judge that all surfaces must be clear of snow, frost and ice for takeoff - the "critical surfaces" bit being for information only. Further down the page it specifically mentions engine inlets and "inlet lips".... I reckon that snow could be classed as being on the inlet lip.
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Old 5th Jan 2010, 21:31
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LBR - are you serious!!!!!

"Those flying the 737 have been trained to cope with unreliable airspeed."

Flight with unreliable airspeed means just that - not a take off with unreliable airspeed!! Good grief!!
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Old 5th Jan 2010, 23:55
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Flight with unreliable airspeed means just that - not a take off with unreliable airspeed!! Good grief!!
The generic briefing is along the lines of aborting before V1 if the aircraft is unsafe or unable to fly. This incident has forced me to carefully re-think what unsafe and unable to fly really mean.

My training says that aborting in the high speed regime is a knife edge of safety with virtually no margin for error or inefficiency. My understanding from said training is that being unsafe to fly means that rejecting the t/o carries significantly less risk than flying. Being unable to fly means a reasonable probability of not being able to control the aircraft.

We know that unreliable airspeed indicators do not affect the controllability of the aircraft, but would probably make reasonable assessments of V1 unreliable. Then, in my opinion, flying would generally be preferable to stopping.

Last edited by Sciolistes; 6th Jan 2010 at 11:20. Reason: Reworded to read more objectively and less critically.
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Old 6th Jan 2010, 06:33
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@threemiles:

Ico contaminated runway takeoff calculations, there's the option to include use of reverse thrust. So better use it then...
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Old 6th Jan 2010, 09:03
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Look guys, I had this kind of failure, after the 80kts callout and I continued.
They elected to stop. Both ways, nobody was injured and the plane reuseable. So job well done.
Accidents need to be analysed as a learning experience, not as a critisizing game.

Flying a commercial jet is not an exact science, although some of our collegues seem to think so. It is an art really and once you realise this, you begin to understand that for each situation, there are several options, each with the potential to be succesfull or disasterous. It is how we handle our chosen option which decides the outcome. (this does not mean we have to break our SOP's and Drills so that we can start inventing new "procedures" on the spot mind you)
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Old 6th Jan 2010, 10:14
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It is dark and snowing. You have been rostered to fly a long flight from the shortest runway you regularly use. The aircraft accelerates slowly due to the weight and the condition of the runway. At the 80 callout you identify a discrepancy between the airspeed indicators. It takes a moment to cross check against the standby and realise what has happened.

You call stop, start the reject and select reverse, which is not very effective as the speed bleeds off. The runway is very slippery and despite max effort the nosewheel slides off the end of the runway. Not a nice scenario. At the end of the day nobody got hurt and the aircraft looks as though it will be back in the air after a good inspection.

I seem to remember a similar incident with BMIbaby at Birmingham, sometime in the last couple of years. I agree with Despegue. Nobody is perfect and with hindsight we can all ponder the other options. But things could have been a lot worse, think Air Florida.
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Old 6th Jan 2010, 10:52
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I didn't actully ever intend to post on this forum, I'd rather leave that to the experts but having read this posting I feel compelled to contrubute for the first and probably the last time.
I'm not a Pilot nor even cabin staff, my only link to the Aircraft industry was many years spent in the Research and Development Dept at Rolls Royce, but for the life of me I do not see what all this fuss is about. A fully trained Pilot made a decision based on the information he had at hand at the time. Nobody else on this forum, especally the armchair sim pilots knows what the aircrafts Pilot saw out of his windscreen. The plane stopped, passengers alighted , no injurys, no deaths, not even injured pride. The pilot made the correct decission end of story. when I fly I want this pilot who dosen't take unnessary chances at the pointy end and I'm sure all of his or her passengers feel the same.
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Old 6th Jan 2010, 16:04
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It seems that the initial investigation has ruled out a performance calculation error and is of the opinion that the aircraft should have have stopped on the runway. Two hypotheses are being investigated: the runway braking action was not as reported or the crew disarmed the autobrake during the RTO. The first is not hard to imagine given the snowfall and temperature. Manual braking in these conditions would not improve matters and has led to some off runway excursions in the past.
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Old 6th Jan 2010, 20:59
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Hmm, should have stopped on runway for sure BUT this incident will probably highlight the fact that contaminated performance is at best a shot in the dark, an estimate of what might happen. Very little of this data is supported by flight testing in the actual conditions and it's only when you come to do a high speed reject on a contaminated runway that the limitations of the data, the runway reports and the tables become apparent. I am willing to bet that, despite the inbuilt safety margins, a large percentage of limiting, contaminated runway departures would result in an overrun in the event of a high speed RTO.
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Old 7th Jan 2010, 01:12
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Re. … contaminated performance is at best a shot in the dark, an estimate of what might happen.

Quotes from CS 25 AMC 1591, (the basis of calculating the performance), i.e. how the operation might be conducted – ‘Can we do this’ attitude.

Operators are expected to make careful and conservative judgments in selecting the appropriate performance data to use for operations on contaminated runways.
Due to the wide variation in possible conditions when operating on contaminated runways and the limitations inherent in representing the effects of these conditions analytically, it is not possible to produce performance data that will precisely correlate with each specific operation on a contaminated surface.


A further quote involving a ‘Should we be doing this’ attitude, similar in the old JAR OPS IEM, but no EU equivalent?

Operation on runways contaminated with water, slush, snow or ice implies uncertainties with regard to runway friction and contaminant drag and therefore to the achievable performance and control of the aeroplane during take-off, since the actual conditions may not completely match the assumptions on which the performance information is based. In the case of a contaminated runway, the first option for the commander is to wait until the runway is cleared. If this is impracticable, he may consider a take-off, provided that he has applied the applicable performance adjustments, and any further safety measures he considers justified under the prevailing conditions.

An adequate overall level of safety will only be maintained if operations in accordance with JAR-25 AMJ 25X1591 are limited to rare occasions. Where the frequency of such operations on contaminated runways is not limited to rare occasions, operators should provide additional measures ensuring an equivalent level of safety. Such measures could include special crew training, additional distance factoring and more restrictive wind limitations.


These types of operation are highly dependent on how the runway conditions are described and the decision makers operational mindset – “can we do this” or “should we be doing this”. Think about it.
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Old 7th Jan 2010, 06:57
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I understand that the runway was reported as wet. It is perfectly conceivable that on line up in the dark it would not be possible to assess that the the stop end might be in a worse state than the beginning of the runway.

Incidentally they should have had additional margin as they were able to use both thrust reversers rather than the one allowed for in the performance calculation.

A fair question would be, is it sensible to plan Canaries flights off marginal runways, in the middle of winter, particularly when there are nearby alternatives?
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Old 7th Jan 2010, 07:09
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Originally Posted by lederhosen
It seems that the initial investigation has ruled out a performance calculation error and is of the opinion that the aircraft should have have stopped on the runway. Two hypotheses are being investigated: the runway braking action was not as reported or the crew disarmed the autobrake during the RTO. The first is not hard to imagine given the snowfall and temperature. Manual braking in these conditions would not improve matters and has led to some off runway excursions in the past.
In the preliminary Report (BFU file number 5X001-10) only states:
The take off was aborted at 120 knots due to different speed indication. The A/C overrun the end of runway.

Last edited by IFixPlanes; 7th Jan 2010 at 08:11.
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Old 7th Jan 2010, 07:39
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Thanks for your input IFixPlanes but sources in Germany are reporting that Lothar Müller of the Bundesstelle für Flugunfalluntersuchungen (federal accident investigation) made these comments on Tuesday.

So in saying I am wrong, I think you may be jumping to conclusions based on partial evidence.

Incidentally do you think the abort started at 120 knots or that that was the highest speed reached after the RTO decision was made?
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