Taxiing incident-What was done wrong here

[punkalouver]

Photos: McDonnell Douglas MD-11(F) Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/FedEx-Express/McDonnell-Douglas-MD-11(F)/1801406/&sid=70c1ce5d76fc3699a4438312640ce48b)

Should you stay on the centreline and take the nosewheel long at the curve?

[18-Wheeler]

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.

[TopBunk]

But yes, you would normally just keep the nosewheel on the centreline or maybe a little on the outside on tight turns.

Is that serious ... on the centreline or maybe a little on the outside in 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!

[notadog]

But yes, you would normally just keep the nosewheel on the centreline or maybe a little on the outside on tight turns.

Um, not in a turn you wouldn't. Particularly when taxiing an MD11. Tight turns in an MD require large amounts of oversteer or you will certainly put the mains in the grass.

[18-Wheeler]

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.

[ManaAdaSystem]

And where would that put you main wheels, Mr 18 wheeler?
You can't even use that technique on a 18 wheeler on the road.

[BOAC]

18 - I do hope you regularly buy lottery tickets - you are obviously a very lucky person.:)

[lazy man]

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.:)

[White Knight]

I can't remember the details of some of the stuff as I haven't flown them for about three years now,

I can believe you forgetting things like where certain switches are after 3 years - but where to put the wheels:\:\:\

[Meikleour]

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!

[BOAC]

Outside my experience, so I think it is TopBunk you should be addressing? Let's hope '18' IS lucky anyway - it is the festive season after all!

[18-Wheeler]

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.

[SNS3Guppy]

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.

[forget]

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. :hmm:

Pages 4 and 5.

http://www.sepiawave.com/documents/white-papers/Airport-Surface-RNP-White-Paper.pdf

[TopBunk]

from 747-400 FCOM1 (whatever you wish to call it)

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.

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.

[punkalouver]

"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 (http://www.billzilla.org/aviationpage5.html)

Back to subject now.

[Neptunus Rex]

From my first Flying Instructor, on Day 1:

"There is never, ever, any excuse for a taxying accident."

[18-Wheeler]

It is all listed on his web page with a link from his PPRuNe profile page. Quite interesting.

Thanks for making the effort to find out - and an extremely easy effort it is as well.
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/435116-aircraft-without-loss-oil-pressure-procedure-9.html#post6117331

[Dan Winterland]

''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.

[EW73]

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 :ooh:

[18-Wheeler]

Wow, thanks for that!

Yes I quit AAI in late 2007 as I was worried they were going to fold in the not too distant future so I decided to get out while I had control over it. I quite enjoyed being there but I also needed a job much closer to home so I could keep an eye on my ageing father (28 years in TAA, ex-727 Captain).
Got a job with QF as an A330 sim instructor but didn't finish the course as I as based in Sydney and decided again that I needed to be right at home to look after him. The only thing I could get in any reasonable time was a return to my old job of over a decade before which was flying rattly old Metros in night freight out of Brisbane. The GFC hit the air freight business hard and most of us in that company had to be let go.
My last flight with them was by coincidence recorded on the very last page of my last logbook and I also took my Dad down from Brisbane to Coffs Harbour so he could meet up with old friends and bring out motorhome back to the Coast.
I'm not much into signs but with that and other factors I reckoned it was time to retire from aviation and that's what I've done. I now spend all my time at home looking after Dad, which is pretty stressful but I figure it's more than fair after all the crap I put him through when I was a kid.
So there you go, the short version of the last few years.

[411A]

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.

Yes, as Guppy aptly demonstrates on a regular basis...:hmm:

[SNS3Guppy]

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.

That's assuredly not the case, but you may have the same challenge as any other: prove it. You can't.

[18-Wheeler]

That's assuredly not the case, but you may have the same challenge as any other: prove it. You can't.

You may well be right, but you can be very sure that you've mistaken me for someone that cares.

[forget]

Enough already! 18 Wheeler's won this one - in spades. :D

[DBate]

As funny and entertaining as this bashing and p***ing contest might be for some, it is interesting to see how this thread has been hijacked within three post from the OP. :}

The mentioned incident happened a couple of months ago and has been discussed here (http://www.airlinepilotforums.com/cargo/54331-fdx-anyone-been-lhbp-lately-ouch.html).

Some more information and more pictures can be found at this page (http://www.airportal.hu/spotter-forum/viewtopic.php?f=31&t=3663).

Neither of the references linked above gives any information on why this happened. I guess we have to wait for the official report.

Fact is, with the main gear located about 31 meters behind your seat on the MD11, a certain amount of oversteering is definately needed in turns.

The tires/brakes of that aircraft were replaced at LHBP and it was back on its way after a short while. Most important thing; nobody got injured! Nothing more than - how shall I say it mildly - a scratch to ones ego. So go on everybody, there is not much to see...

Now back to topic please.

DBate

[JammedStab]

I wonder if the Fedex guy moved to the left of centreline on the taxiway because he was approaching a tight turn to the right . Does anyone else do this especially in widebody jets.?

Also, it seems that there mey be differing opinions on how to properly taxi a 747 when it comes to turns especially tighter turns. I would think there would be something in the Boeing manual that could be pasted here. Is it quite different than the other widebody jet taxiing techniques?

[BOAC]

..er Post #15 do you?

[notadog]

I wonder if the Fedex guy moved to the left of centreline on the taxiway because he was approaching a tight turn to the right . Does anyone else do this especially in widebody jets.?

Also, it seems that there mey be differing opinions on how to properly taxi a 747 when it comes to turns especially tighter turns. I would think there would be something in the Boeing manual that could be pasted here. Is it quite different than the other widebody jet taxiing techniques?

Having flown the B747, and now flying the MD11, I can tell you that the 747 is far easier to taxi and maneuver on the ground. The unlocking body gear makes taxiing a 747 quite easy. I have made many tight turns that look imposible, but done with ease.

The MD11 is very different. To make a tight turn, a large amount of oversteer is necessary. In this case, I would suspect that the pilot was distracted or not attentive and permitted the aircraft to drift left of the centerline. On this taxiway, it would not have been necessary to extend the nose very far past the centerline to make the turn.

It is very important to know the geometry of the landing gear while taxiing, IOW, how do you know where the mains are when you are moving down a taxiway? On the MD11, when sitting in the left seat, the left main is about even with the lower outboard corner of the left windshield. The right main is about three inches to the right of the center post of the windshield. The nose gear is centered when the taxi line is lined up with your right knee.

The nose gear is 22' behind the Capt's seat, the mains about 125' behind.

To make a 90 deg. turn one must taxi past the centerline of the intersecting taxiway until the cockpit is just past the far edge of the taxiway that you are going to turn onto. Then, make the turn. It's a bit disconcerting at first...

Making a 180 on a runway is definitely not for the faint of heart, and there is a neat trick for doing it correctly, but it's best not to be in a situation where one has to do it.

In the picture, the a/c is still on a straight portion of the taxiway, displaced significantly from the centerline. It should be on the centerline at that point. The Capt. should have known that his left main was very close to being off the taxiway. I can only assume that he was distracted, or that he needs some remedial taxi training.

[punkalouver]

Interesting. But you are not going to leave us hanging here about the 180° turn technique are you?

[con-pilot]

Not taking sides in this fight, but.....

I have never flown a 747, however, I do have 7,000+ hours in the 727, 3,700 in the left seat. I cannot remember the number of airports/taxiways/ramps/parking areas that if I had kept the nose wheel on the center line of the previous mention places I would had to have pulled a 'Con-Air' and had the prisoners come off the aircraft and help put the aircraft out of the grass and/or mud/or whatever. And this, remember was in a 727, not a 747.

Now if I had only had to operate out of JFK and airports such as it, well I probably would have been able to keep the nose wheel on the aforementioned center lines.

[411A]

But you are not going to leave us hanging here about the 180° turn technique are you?
Suspect its about the same as with the L1011....pilots backside way out over the grass prior to coming 'round with the tiller.