Print from Airliners.net discussion forum
http://www.airliners.net/aviation-forums/general_aviation/read.main/5616367/

Topic: SAS Plane Off The Runway At CPH
Username: SKAirbus
Posted 2012-11-21 01:15:19 and read 15990 times.

As if SK's problems weren't bad enough, this morning this happened (in Norwegian):

http://www.vg.no/reise/artikkel.php?artid=10071183

Basically, the A319 (OY-KBR - "Sten Viking") left the runway after what a passenger described as "higher than normal taxi".

Seems that the aircraft knocked down a taxi sign and made some good tracks in the grass but nothing major. Just more bad publicity for the airline that it doesn't need! Will be interesting to see what caused this.

The flight was operating from OSL as SK453, departing at 07:40, landing at 09:00.

[Edited 2012-11-21 01:17:14]

Topic: RE: SAS Plane Off The Runway At CPH
Username: qf340500
Posted 2012-11-21 01:21:17 and read 15943 times.

this can happen, has normally NOTHING to do with the airline

Topic: RE: SAS Plane Off The Runway At CPH
Username: CPH-R
Posted 2012-11-21 02:11:25 and read 15695 times.

Looks like it happened on taxiway B4, which is a high-speed turnoff from runway 22L going into a relatively sharp right-hand turn.

According to a SAS spokesperson, there's been problems with that particular taxiway before.

Topic: RE: SAS Plane Off The Runway At CPH
Username: SKAirbus
Posted 2012-11-21 02:19:58 and read 15626 times.

Quoting qf340500 (Reply 1):
Looks like it happened on taxiway B4, which is a high-speed turnoff from runway 22L going into a relatively sharp right-hand turn.

According to a SAS spokesperson, there's been problems with that particular taxiway before.

True but you'd think SAS pilots would be used to this. Seems like the pilot was going too fast and obviously the wheel angle is dependent on the speed the aircraft is moving at.

Quoting qf340500 (Reply 1):
this can happen, has normally NOTHING to do with the airline

It can have implications for training etc and could also indicate a technical problem with the aircraft. Even if it has nothing to do with SAS, the media will not see it that way... Just more bad publicity.

Topic: RE: SAS Plane Off The Runway At CPH
Username: g500
Posted 2012-11-21 05:31:52 and read 14982 times.

I'm sure the airplane sustained no damage or limited damage. This is a PR problem more than anything else

Topic: RE: SAS Plane Off The Runway At CPH
Username: Lanas
Posted 2012-11-21 11:57:28 and read 11356 times.

Sorry if the question is stupid but, how do they bring the aircraft back on the asphalt?

Do they have special tow trucks, or would the normal ones do OK?

Topic: RE: SAS Plane Off The Runway At CPH
Username: photoshooter
Posted 2012-11-21 12:36:39 and read 10719 times.

Quoting Lanas (Reply 5):
Sorry if the question is stupid but, how do they bring the aircraft back on the asphalt?

Do they have special tow trucks, or would the normal ones do OK?

I'm not entirely sure but most tow trucks can drive on grass or open field.. I see them driving on grass regularly at EIN so it shouldn't be a problem.

No doubt they will have to check the wheels of the Airbus 319 after they've done that   

Topic: RE: SAS Plane Off The Runway At CPH
Username: mcdu
Posted 2012-11-21 15:31:05 and read 8322 times.

The skid mark from the nose gear prior to the grass would only occur if the tiller was turned full in hopes of turning. The A319/320 nose gear is notorious for having very little grip on wet pavement due to the fact the outside wheel in the turn will be off the ground. Not much rubber remaining to steer. As far as the airplane went in to the grass it definitely looks like it was traveling at a good clip when it departed the surface. The pilot must have been attempting to turn right with full tiller during the event to produce that skidmark.

Topic: RE: SAS Plane Off The Runway At CPH
Username: prebennorholm
Posted 2012-11-21 19:01:26 and read 6607 times.

This is strange.

It happened on a high speed turn off. It made the 45 degrees right turn off the runway without problems. Then after a few hundred yards it should turn rather sharply 135 degrees to the right for taxi back to the terminal on a taxiway parallel to the runway.

In that 135 degrees turn it just continued straight ahead, knocking down a signpost and continuing out on the grass on wet and soft ground.

I have been on planes taking that same turn at least a hundred times. On all sorts of planes, including 319, 320 and 321. They always do that turn very slowly - at a speed from which they could brake to a standstill in a few yards. Never ever have I been on a plane which could have made such long marks in the grass even if the pilot "forgot" to turn.

Daylight, home base, clear weather, hundreds of planes from all over the world make that same turn every day unless there is a strong wind from an unusual direction.

It is really strange. The pilot must have fallen asleep or such. It will be interesting to read the report.

Topic: RE: SAS Plane Off The Runway At CPH
Username: Navigator
Posted 2012-11-21 23:26:03 and read 4854 times.

Quoting prebennorholm (Reply 8):
I have been on planes taking that same turn at least a hundred times. On all sorts of planes, including 319, 320 and 321. They always do that turn very slowly - at a speed from which they could brake to a standstill in a few yards

I have other experiences here... I have been on SAS-planes on 22L many many times and this year I have been on a few planes that have turned off the runway very very fast. Last time I noticed this was in the morning rush when we came from Stockholm. Another plane was just behind on approach. I remember I said to my friend that the taxied much faster than comfortable when turning off. I think this flight went too fast in the turn.

Topic: RE: SAS Plane Off The Runway At CPH
Username: EBGflyer
Posted 2012-11-22 00:30:10 and read 4326 times.

Quoting prebennorholm (Reply 8):
This is strange.

It happened on a high speed turn off. It made the 45 degrees right turn off the runway without problems. Then after a few hundred yards it should turn rather sharply 135 degrees to the right for taxi back to the terminal on a taxiway parallel to the runway.

I don't think it's that strange. The first turn is not very sharp, but the second turn is and this is where the excursion happened.

Topic: RE: SAS Plane Off The Runway At CPH
Username: prebennorholm
Posted 2012-11-22 19:43:53 and read 3369 times.

I have been wondering why this could happen. One wild guess:

Right after the high speed turn off many flight crews shut down one engine and continue taxi to the gate on one engine only. Can some mismanagement or hidden failure have caused a hydraulic failure? On nose wheel steering? On wheel brakes? Or even on both?

Quoting EBGflyer (Reply 10):
I don't think it's that strange. The first turn is not very sharp, but the second turn is and this is where the excursion happened.

Ha, ha! I will tell that to the police next time I drive off the road onto the pedestrian pavement: "The turn was very sharp, I couldn't make it". I'm sure they will understand.  Wow!
Quoting Navigator (Reply 9):
I have other experiences here... I have been on SAS-planes on 22L many many times and this year I have been on a few planes that have turned off the runway very very fast.

Sure they do. That's what high speed turn offs are made for.

But this plane made a perfect turn off the runway, only to continue straight ahead a few hundred yards further on where it should make a sharp 135 deg. turn onto a parallel taxiway.

Topic: RE: SAS Plane Off The Runway At CPH
Username: rcair1
Posted 2012-11-23 15:11:01 and read 2993 times.

Quoting prebennorholm (Reply 8):
Daylight, home base, clear weather, hundreds of planes from all over the world make that same turn every day unless there is a strong wind from an unusual direction.

It is really strange. The pilot must have fallen asleep or such. It will be interesting to read the report.

Looking at the layout of CPH - I'm wondering if the PF simply confused this high speed exit with others. Most of the others do not have such a sharp 2nd turn. If he/she was 'thinking' of a different high speed exit - one that is much gentler - or more typically bends back to merge onto the taxiway - they could have simply held onto too much speed.

Topic: RE: SAS Plane Off The Runway At CPH
Username: prebennorholm
Posted 2012-11-23 18:03:59 and read 2856 times.

Quoting rcair1 (Reply 12):
Looking at the layout of CPH - I'm wondering if the PF simply confused this high speed exit with others. Most of the others do not have such a sharp 2nd turn. If he/she was 'thinking' of a different high speed exit - one that is much gentler - or more typically bends back to merge onto the taxiway - they could have simply held onto too much speed.

I see what you mean. But still it is very hard to "buy" that explanation.

For a few hundred yards they are looking in clear daylight on a big signpost and green grass right in front of them. All SK Airbuses are based at CPH, therefore most likely it had a Danish crew. They have made that turn at least hundreds, and most likely thousands of times before, as have hundreds of thousands of pilots from all over the world before them, in darkness, snow, fog.

That crew knows CPH better than we know our living room.

And there is nothing unusual about the taxiway configuration. A roughly 45 deg. high speed turn off followed by a few hundred yards straight taxiway for continued braking, then a 135 deg. turn to go back on a parallel taxiway, there are hundreds if not thousands of similar configurations at airports. It is pretty much the norm all over the world.

Had it been a crew from New Zealand, landing for the first time at CPH, at darkness and light fog, then....

There must be some other explanation.

The 320 family has a rather unique hydraulic system. If differs from for instance the 330 in having only one hydraulic pump on each engine, powering only half of the system. And then it relies on the APU for redundancy in case of an engine shut down. With one engine stopped there is sort of crossfeed between the two systems. The remaining pump powers a hydraulic motor which powers the otherwise unpowered hydraulic system. That hydraulic motor is the one which often barks like a mad dog in the belly of the plane when the first engine is started. I wonder if some mismanagement - or undetected failure - can have prevented power on the wheel brakes and/or nose wheel steering for a few critical seconds during the transition from two pumps to single pump operation.

It's a wild guess. It will be interesting to see what the report comes up with.

Topic: RE: SAS Plane Off The Runway At CPH
Username: rcair1
Posted 2012-11-24 08:53:56 and read 2604 times.

Quoting prebennorholm (Reply 13):
They have made that turn at least hundreds, and most likely thousands of times before,

On average - Hundreds - yes - not sure about thousands. But - could this have been a relatively new crew?

Quoting prebennorholm (Reply 13):
can have prevented power on the wheel brakes and/or nose wheel steering for a few critical seconds during the transition from two pumps to single pump operation.

It's a wild guess. It will be interesting to see what the report comes up with.

I was wondering that myself. Obviously the nose wheel steering was working - you can see the skid mark from the nose wheel as it skidded sideways.

However, I wonder if perhaps there was a wheel brake issue. Certainly - if they were braking and for some reason only the left brake was working correctly - that could contribute to both not slowing down and pulling to the left.

The report will be interesting.


The messages in this discussion express the views of the author of the message, not necessarily the views of Airliners.net or any entity associated with Airliners.net.

Copyright © Lundgren Aerospace. All rights reserved.
http://www.airliners.net/