Runway excursion by DL MD-80
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Ancient Mariner, you asked for a report. Do you want the one when I had to clear 3000 pop fans, mostly teenage girls, from a wooden building after what the police advised was a credible bomb scare at the height of IRA activity in mainland Britain or the time I had to clear a conference hall, the 200 delegates consisting of government ministers, senior ATC delegates and airline managers from around the world, after smoke and fire alarms were set off?
SLFplatine, If you would change your comment to "it would be the rare passenger......." I would agree with you.
I know plenty of non pilot/crew passengers who are either connected to aviation professionally or are just enthusiasts who are interested in more than number collecting and photography, who are well versed in the technical aspects of flight, meteorology, operations and the causes of accidents and incidents to have a detailed understanding of what may go wrong, myself included.
SLFplatine, If you would change your comment to "it would be the rare passenger......." I would agree with you.
I know plenty of non pilot/crew passengers who are either connected to aviation professionally or are just enthusiasts who are interested in more than number collecting and photography, who are well versed in the technical aspects of flight, meteorology, operations and the causes of accidents and incidents to have a detailed understanding of what may go wrong, myself included.
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Runway Conditions
let's see ..... you shoot an approach to a snowy icy runway in low visibility, with a quartering tailwind, to a relatively short runway by airline standards, in a aircraft with twin tail mounted engines, and you are surprised when you weather vane the airplane off the runway when you apply reverse thrust? I would proffer that there was probably no problem with the brakes themselves, just the fact there was most likely little to no braking available due to runway conditions.
Last edited by MotCap; 9th Mar 2015 at 20:07. Reason: Runway Length ..... standby for flame .. i can take it
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NTSB Issues Second Update on the Delta Flight 1086 Accident at LaGuardia
Issued 3/9/2015
NTSB Issues Second Update on the Delta Flight 1086 Accident at LaGuardia
Issued 3/9/2015
NTSB Issues Second Update on the Delta Flight 1086 Accident at LaGuardia
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The reverse thrust on the MD88 can block out the rudder so rudder control could have been lost when max reverse was applied shortly after touchdown causing the deviation to left as the report indicates. Reducing or removing reverse thrust would once again make rudders effective. This would have been required as soon as the drift to the left began to return to center line of runway. Reverting to manual braking would also help return to centerline with differential braking. RWY 13 of course doesn't give you the luxury of cancelling reverse for long.
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Anyone know if the MD-80 series can be steered with judicious use of spoilers once the nose wheels are planted? It would probably require deselection of spoilers for braking though, but if braking is nil, it might give some options.
Not an aircraft that I have flown, so just speculating.
Not an aircraft that I have flown, so just speculating.
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spoilers are not for ground steering. machin bird perhaps you can tell me what plane could be steered on the ground with spoilers?
IT has been reported in the NTSB report linked above that the SPOILERS DID NOT< REPEAT NOT DEPLOY AUTOMATICALLY and the F/O Quickly deployed them manually.
We know this can happen when the variety of sensors detecting and interpreting that the plane is on the ground get fooled somehow, so we are ready to deploy the spoilers manually.
AS some of the same things which tell the spoilers to come up are also the same things that might start the auto brakes working, maybe there is a connection? maybe not?
Coming out of reverse like bubbers 44 has mentioned is a well known technique and it is probably better to go off the end of the runway at 40 knots than the side of the runway at 100 knots.
IT has been reported in the NTSB report linked above that the SPOILERS DID NOT< REPEAT NOT DEPLOY AUTOMATICALLY and the F/O Quickly deployed them manually.
We know this can happen when the variety of sensors detecting and interpreting that the plane is on the ground get fooled somehow, so we are ready to deploy the spoilers manually.
AS some of the same things which tell the spoilers to come up are also the same things that might start the auto brakes working, maybe there is a connection? maybe not?
Coming out of reverse like bubbers 44 has mentioned is a well known technique and it is probably better to go off the end of the runway at 40 knots than the side of the runway at 100 knots.
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To keep you gents from speculating excessively, remember I'm a tactical guy, and my F-4 could be steered with the spoilers fairly well, which was useful when putting out the drag chute on a slippery runway. (talk about weather cocking)
I'm assuming that the MD-80 series has more than just ailerons for roll control, and the additional surfaces could be used for steering if not being used for slowing down the aircraft. Now if I've made a bad assumption, I'll make these posts of mine go away.
I'm assuming that the MD-80 series has more than just ailerons for roll control, and the additional surfaces could be used for steering if not being used for slowing down the aircraft. Now if I've made a bad assumption, I'll make these posts of mine go away.
Originally Posted by Machinbird
F-4 could be steered with the spoilers fairly well, which was useful when putting out the drag chute
Little Maddog does not have asymmetric spoilers on the ground. Big Maddog probably the same.
Further evidence from the FDR should answer a few questions regarding the behavior of the braking, spoiler and T/R systems. I say should because I'm not sure that wheel speed and anti-skid valve parameters are monitored by the FDR on an '80s vintage MD-80. Anyone know? If not, then maybe the installed QAR does?
Good point made by bubbers regarding the loss of rudder effectiveness caused by reverse thrust "blanking" which occurs on many tail pylon mounted engine equipped airplanes. Have noted that on all such types I've flown. A left crosswind component of 7 knots doesn't seem like very much, but the "parachute effect" of T/Rs dragging the tail downwind (to the right) and the loss of rudder effectiveness (promoting a weather-vane tendency) combined might create a noticeable left turning tendency. On a slick runway, these factors have contributed to MD-80 landing roll-out directional control difficulties in the past. Good FDR or QAR data may answer those questions.
That must be a horrible feeling when you realize you're going off the runway in spite of all your efforts to prevent it. Anyone who's landed on a slippery runway has probably had their moments of doubt, but actually going off? I sure don't wanna know. Glad it didn't turn out as bad as it could have.
Good point made by bubbers regarding the loss of rudder effectiveness caused by reverse thrust "blanking" which occurs on many tail pylon mounted engine equipped airplanes. Have noted that on all such types I've flown. A left crosswind component of 7 knots doesn't seem like very much, but the "parachute effect" of T/Rs dragging the tail downwind (to the right) and the loss of rudder effectiveness (promoting a weather-vane tendency) combined might create a noticeable left turning tendency. On a slick runway, these factors have contributed to MD-80 landing roll-out directional control difficulties in the past. Good FDR or QAR data may answer those questions.
That must be a horrible feeling when you realize you're going off the runway in spite of all your efforts to prevent it. Anyone who's landed on a slippery runway has probably had their moments of doubt, but actually going off? I sure don't wanna know. Glad it didn't turn out as bad as it could have.
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Hi Bird, referring to You. Spoilers can not be used differentially at ground mode,so they are more or less just aerodynamic brakes. Drags,if you prefer. And thinking of MD 80,a needlepin where everything happens so far back in there,the whole concept must be thought and adjusted that way. The way i thought of it,was being balanced in the nose of a very delicate mass,bit like being a goose. And so it behaves also on landing,sometimes nice,sometimes not so. Braking actions .40-.30 may be better for personal landings,but as here,i think the guys got just trapped by the circumstances. 80,is no-one`s favourite to skate around with. In slippery runways,it sure is a handful to keep it straight,so i would not find any blame on them. Things just happen,unavoidables when you do something. Incidents,to avoid accidents.
I no longer have access to MD-80 Lamm Schematics, but from memory main gear WOW switch made and main gear wheel spin-up is required to trip auto brakes and auto spoilers ON. Is it possible that the friction at the touchdown point was so low that mainwheel spin-up did not occur?
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Sure lots of sniping at the bill paying guests aboard aircraft...... Acting sometimes like herds of untrained , ah, ah people and angry so many of the SLF are just so stoopid and unwise in the ways of acting in event of unexpected emergencies.
Don't think I have read comments in the thread by those SLF dummies, reminding the operators that SLF don't ask to be put in unplanned emergency situations that over the years have too often been caused by the operators up front, whether being incompetent on occasion or willfully disregarding SOP's or federal regulation or regulations.
Note, I am not guessing the cause of this latest event or assigning blame
Don't think I have read comments in the thread by those SLF dummies, reminding the operators that SLF don't ask to be put in unplanned emergency situations that over the years have too often been caused by the operators up front, whether being incompetent on occasion or willfully disregarding SOP's or federal regulation or regulations.
Note, I am not guessing the cause of this latest event or assigning blame
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TWB, yes WOW and main gear wheel spinup as I recall is required for auto spoiler deployment so was probably why manual deployment was required.
Differential reverse is not taught but once rudder is effective again using more right reverse would have helped stop the drift to left. One of our check airmen told me differential reverse is like stopping a horse and pulling the reins to keep straight so I tried it and it works.
Differential reverse is not taught but once rudder is effective again using more right reverse would have helped stop the drift to left. One of our check airmen told me differential reverse is like stopping a horse and pulling the reins to keep straight so I tried it and it works.
TWB
Yes...had to manually deploy spoilers a couple of times.(lack of wheel spin up).
They are not differential.
Nearly ran off the end of Gottenborg.IIRC...DC9-51..after landing behind an AF bus ...rwy reports good but Bus used lots of reverse which melted the frozen, sanded rwy surface which refroze and gave us a skating rink.
Had to have the engines borescoped....as set emergency reverse at lowish speed...engines surged several times...but am here to tell the tale.
They are not differential.
Nearly ran off the end of Gottenborg.IIRC...DC9-51..after landing behind an AF bus ...rwy reports good but Bus used lots of reverse which melted the frozen, sanded rwy surface which refroze and gave us a skating rink.
Had to have the engines borescoped....as set emergency reverse at lowish speed...engines surged several times...but am here to tell the tale.
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I have to hand it to you guys. A masterful stroke about all the hullabaloo wrt evacuation, bags etc...distracting from the issue of crew and aircraft performance in this incident.
In the 737 for example, part of the sequence required of actions if going sideways on a slippery runway is to select idle reverse. Much depends on how you select idle reverse. if you inadvertently slam the reverse levers fully down in the haste to get idle reverse, chances are you may go past the idle reverse detent especially if it is worn or ill-defined.
It is quite possible to then finish up with forward thrust because of the time it takes to run the RPM down towards idle. You will easily find yourself with N1 winding down past 45- 55% in forward thrust. This will accelerate the aircraft down the runway when you need to be slowing up.
It is quite possible to then finish up with forward thrust because of the time it takes to run the RPM down towards idle. You will easily find yourself with N1 winding down past 45- 55% in forward thrust. This will accelerate the aircraft down the runway when you need to be slowing up.