Taxiing incident-What was done wrong here
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Taxiing incident-What was done wrong here
Photos: McDonnell Douglas MD-11(F) Aircraft Pictures | Airliners.net
Should you stay on the centreline and take the nosewheel long at the curve?
Should you stay on the centreline and take the nosewheel long at the curve?
That seems to be a separate question to what happened in that photo as that plane was waaay off to the left of the centreline. I flew with some airline guys that really drummed into me the importance of keeping your eyes outside when on the ground and when I was left-seat I did the same with all my FO's.
But yes, you would normally just keep the nosewheel on the centreline or maybe a little on the outside on tight turns.
But yes, you would normally just keep the nosewheel on the centreline or maybe a little on the outside on tight turns.
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But yes, you would normally just keep the nosewheel on the centreline or maybe a little on the outside on tight turns.
Your profile says 747 Captain, but with an answer like that I start to doubt it.
That techique may work fine in 737/320-types, but I shudder to think the results of taxying around JFK (for example) with that technique.
The the OP, to ensure the main wheels stay well within the taxyway driving deep into the turn with the nosewheel is the approved technique. That may well see the nosewheel of a 747 3/4 of the was to the outside of the corner from the centreline in a really tight turn. The main gear will still be biased towards the inside of the turn.
What the MD11 guys did, I suspect, was to lose all situational awareness possibly through lack of concentration and they went off the outside of the bend. You certainly don't go in as deep as that!
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But yes, you would normally just keep the nosewheel on the centreline or maybe a little on the outside on tight turns.
Yes I really was a 747 Captain, flew them for a decade and with plenty of people from here as well.
I can't remember the details of some of the stuff as I haven't flown them for about three years now, apologies if I got it wrong.
I do remember than the nosewheel sits pretty much right under the FE though, so that's where you need to visualise it being run along the taxiway.
I can't remember the details of some of the stuff as I haven't flown them for about three years now, apologies if I got it wrong.
I do remember than the nosewheel sits pretty much right under the FE though, so that's where you need to visualise it being run along the taxiway.
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The picture does not depict a tight turn, certainly not something I'd
think would require any correction away from centerline. P.S.: I've never
taxied anything bigger than a DC9, so ignore my input if you want.
think would require any correction away from centerline. P.S.: I've never
taxied anything bigger than a DC9, so ignore my input if you want.
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Originally Posted by 18-wheeler
I can't remember the details of some of the stuff as I haven't flown them for about three years now,
TOPBUNK: Its been a while off the B747 but as far as I recall, on the Jumbo, at large nosewheel deflection angles, the body gear steering jacks unlock and deflect the Body Gear in the OPPOSITE direction to the turn. This has the effect of really tightening the tun and obviates the need for significant oversteer.
So 18 may have been lucky but he may also have simply been using the correct technique!
So 18 may have been lucky but he may also have simply been using the correct technique!
Last edited by Meikleour; 13th Dec 2010 at 11:49.
Luck had nothing to do with it, you pathetic bunch. I have better things to do that to sit here and relive old times to impress you lot.
I said I don't remember that bit as clearly as you'd like but stick me in the seat and I'd be fine.
I said I don't remember that bit as clearly as you'd like but stick me in the seat and I'd be fine.
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Out of curiosity, 18 wheeler, you recently had a lively thread in which you were flying a metroliner, I believe, and had questions regarding oil pressure procedures. This after you were a 747 captain? Not to doubt your veracity based on your current employment, but it does seem unusual.
So far as taxiing the 747, as it's what I currently fly, I'll have to disagree with your assessment. Sticking to the centerline with the nosewheel, especially in turns, is nearly guaranteed to overrun the side of a taxiway or runway. Taxiing beyond the turning point with the nosewheel and oversteering, often to the edge of the opposite side of the runway or taxiway, is necessary to avoid the mains tromping through the grass, taxiway lights, or runway lights. Turning into one's parking spot, or any 90 degree turn, involves taxiing past the line on which one wishes to turn, by a substantial margin, before swinging into the turn and lining up.
Your description might appear true if you were a passenger in a 747, as one doesn't see the amount of oversteer really unless one is in the cockpit (one is seated well past the nosegear, and thus sees the most exaggerated view). Your description isn't accurate for someone who has flown the 747, however.
I can understand not remembering memory items, speeds, limitations, and procedures; these are type-specific and there's no reason to retain them if you're not flying the airplane currently. The nature of the way the airplane moves when being taxied about, however, is very exaggerated and distinctive. It's a big, heavy airplane, and one sits very high; it's unlike any other. I would think that forgetting taxiing and the distance by which one must oversteer would be a difficult thing, especially after only two or three years.
Your profile does say that you're currently a B747 captain, by the way.
So far as taxiing the 747, as it's what I currently fly, I'll have to disagree with your assessment. Sticking to the centerline with the nosewheel, especially in turns, is nearly guaranteed to overrun the side of a taxiway or runway. Taxiing beyond the turning point with the nosewheel and oversteering, often to the edge of the opposite side of the runway or taxiway, is necessary to avoid the mains tromping through the grass, taxiway lights, or runway lights. Turning into one's parking spot, or any 90 degree turn, involves taxiing past the line on which one wishes to turn, by a substantial margin, before swinging into the turn and lining up.
Your description might appear true if you were a passenger in a 747, as one doesn't see the amount of oversteer really unless one is in the cockpit (one is seated well past the nosegear, and thus sees the most exaggerated view). Your description isn't accurate for someone who has flown the 747, however.
I can understand not remembering memory items, speeds, limitations, and procedures; these are type-specific and there's no reason to retain them if you're not flying the airplane currently. The nature of the way the airplane moves when being taxied about, however, is very exaggerated and distinctive. It's a big, heavy airplane, and one sits very high; it's unlike any other. I would think that forgetting taxiing and the distance by which one must oversteer would be a difficult thing, especially after only two or three years.
Your profile does say that you're currently a B747 captain, by the way.
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At airports where there is no fillet the pilot is required to use “judgmental oversteering” to maneuver the aircraft, where the nosewheel is purposely steered outside the centerline, thus keeping the fuselage from deviating to the inside of the curve.
Pages 4 and 5.
http://www.sepiawave.com/documents/w...hite-Paper.pdf
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from 747-400 FCOM1 (whatever you wish to call it)
The flight crew sit an additional ~2m ahead of the nose wheel.
18-wheeler
I have no doubt that if you were to be sat in the seat you would recall the desired techique, but as I and others have pointed out, we feel your recollection is less than perfect.
Seasons greetings to you and yours.
Meikleour
See the above - you are correct, the body gear steering helps tighten the turn radius and also helps reduce tyre scrubbing.
I have looked through manuals and they state that, for the Body Gear Steering deactivated condition:
1. Centre point for the radius of turn is inside the inboard main gear
2. It is 48ft from the aircraft centreline
3. It is also 70ft from the outboard main gear
4. It is also 100ft from the nose wheel.
So imagine taxyingwith the outboard mains on the very edge of the runway; the pivot point is 70ft to the left of the runway edge; with optimum technique the nose wheel will end 100ft to the left of the pivot point giving you the minimum pavement width for a 180degree turn of 70+100ft = 170ft (Body Gear Steering deactivated).
This compares to a quoted 153ft for Body Gear activated.
So Body Gear reduces 180deg turn radius by 17ft.
Back to the original question though. Using the above numbers and some geometry, I will leave you to determine where the inside main gear wheels will be on taxyways of differing widths, and hence the appropriate tracking of the nose wheel.
The body gear steering is activated when the nose gear angle exceeds 20° and the taxi speed is below 20 kts. It is difficult to assess wing tip clearance from the flight deck as the wing tip moves further out during turns. The distance between the nose(wheel) and body gear is 27m, hence the flight deck must track outside turns to enable the main wheels to remain on the centreline.
18-wheeler
I have no doubt that if you were to be sat in the seat you would recall the desired techique, but as I and others have pointed out, we feel your recollection is less than perfect.
Seasons greetings to you and yours.
Meikleour
See the above - you are correct, the body gear steering helps tighten the turn radius and also helps reduce tyre scrubbing.
I have looked through manuals and they state that, for the Body Gear Steering deactivated condition:
1. Centre point for the radius of turn is inside the inboard main gear
2. It is 48ft from the aircraft centreline
3. It is also 70ft from the outboard main gear
4. It is also 100ft from the nose wheel.
So imagine taxyingwith the outboard mains on the very edge of the runway; the pivot point is 70ft to the left of the runway edge; with optimum technique the nose wheel will end 100ft to the left of the pivot point giving you the minimum pavement width for a 180degree turn of 70+100ft = 170ft (Body Gear Steering deactivated).
This compares to a quoted 153ft for Body Gear activated.
So Body Gear reduces 180deg turn radius by 17ft.
Back to the original question though. Using the above numbers and some geometry, I will leave you to determine where the inside main gear wheels will be on taxyways of differing widths, and hence the appropriate tracking of the nose wheel.
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"Out of curiosity, 18 wheeler, you recently had a lively thread in which you were flying a metroliner, I believe, and had questions regarding oil pressure procedures. This after you were a 747 captain? Not to doubt your veracity based on your current employment, but it does seem unusual."
It is all listed on his web page with a link from his PPrune profile page. Quite interesting.
Bill Sherwood's Aviation Page - 4
Back to subject now.
It is all listed on his web page with a link from his PPrune profile page. Quite interesting.
Bill Sherwood's Aviation Page - 4
Back to subject now.
Last edited by punkalouver; 13th Dec 2010 at 20:21.
It is all listed on his web page with a link from his PPRuNe profile page. Quite interesting.
Unsurprising SNS3Guppy didn't have the nous to do that simple task and has indeed himself been proven beyond any doubt to be .... ah-hem .... full of it.
http://www.pprune.org/tech-log/43511...ml#post6117331
''So 18 may have been lucky but he may also have simply been using the correct technique!''
Those who have actually flown the 747 will know this is correct. The body gear steering makes the pivot point of the aircraft somewhere around the leading edge at the root. Sitting 32' up menas that there is little perceptable lead required. I moved from the 747 to the A320 series and there is far more lead required on the 321 compared with the 747.
Those who have actually flown the 747 will know this is correct. The body gear steering makes the pivot point of the aircraft somewhere around the leading edge at the root. Sitting 32' up menas that there is little perceptable lead required. I moved from the 747 to the A320 series and there is far more lead required on the 321 compared with the 747.
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Gentlemen...
From the viewpoint of an experienced aviator of some 14,000 flight hours logged over a 25 year flying career, some 5,000 of which were logged as B747-1/2/3/SP, and much of that in the company of 18-Wheeler.
His competence as an operator of heavy metal has never been in any doubt by me or anyone I'm aware of.
He is a professional airman, take that as read, he doesn't do it any other way!
and Yes, he did recently fly Metroliners, the details of which are public at his discretion!
and No, we're not brothers, in fact I haven't see/spoken with him for a couple of years now.
I suggest you'all find something constructive to chat about, and stop this negative nonsense about a professional colleague.
EW73
From the viewpoint of an experienced aviator of some 14,000 flight hours logged over a 25 year flying career, some 5,000 of which were logged as B747-1/2/3/SP, and much of that in the company of 18-Wheeler.
His competence as an operator of heavy metal has never been in any doubt by me or anyone I'm aware of.
He is a professional airman, take that as read, he doesn't do it any other way!
and Yes, he did recently fly Metroliners, the details of which are public at his discretion!
and No, we're not brothers, in fact I haven't see/spoken with him for a couple of years now.
I suggest you'all find something constructive to chat about, and stop this negative nonsense about a professional colleague.
EW73