Runway Line Up Technique

[777boeings]

It was mentioned to me a couple of years ago, that when lining up on a runway for take off, the yellow line should be followed throughout the line up. The yellow line however, often describes a shallow turn and therefore uses up more available runway.
Prior to this I had always practiced a ninety degree turn in order to maximize take off distance.
Does anyone know if there is any formal documentation to support line up following the line?
I’m not really looking for opinions here but rather some validation of the recommended technique so I can pass the information to my trainees.

[The Actuator]

The yellow line is a turn off line from the runway to the taxiway. Line up using a 90 degree turn, to maximise runway length so as to validate your take off speeds and distance calculations.

[SuperRanger]

I agree with Actuator, yellow line is for led-out not led-in. Personally, I use 90deg to maximize the runway. Our specific takeoff charts calc allows for 75' of line-up.

Sr

[de facto]

Max alignment distance should be in your perf data.(under ASDA line up).
Boeing recommends if at all possible use shortest line up every flight(most of time it is a 90 degree line up), every meter saved is a good meter!

[BOAC]

It is not uncommon for runway performance charts to specify the line-up manoeuvre used for the relevant calculations.

[Checkboard]

The entire runway surface is inspected for FOD (Foreign Object Damage), is built to the same weight spec and has the same wing clearances at the edges for obstacles - so there is no reason to specifically follow a yellow line on a runway (providing you don't taxi off the edge, of course!)

On a taxiway, however, different areas are built to different weight spec, the lines are painted specifically to guarantee wing clearance, and off the yellow line you find much more FOD.

I once took a shortcut, off the yellow lines, on the apron and picked up a nail in a tyre - so spent four hours with an AOG aircraft waiting for a replacement. At least if you follow the lines, you have a good chance that the aircraft ahead has followed the lines, and picked up any FOD before you.

[break_break]

Actuator has answered correctly as far as the yellow line is concerned.
In addition, to date, there hasn't been one single case of heavy MTOW (even pass the 1000K IBs mark) running off the other end due to poor line up technique. However, you can easily name quite a few incidents of big tubes scrubbing some mud/grass/taxi edge lights or even getting stuck during line up due to the every-inch-counts mentality (well at least that's how most of us were taught anyway).
The performance does allocate some sacrifices and conservatism, depending on a/c type. I personally will neither follow the yellow nor a 90deg, somewhere in between, with careful judgement of my wheel clearance being the priority is IMHO, the most practical way to line up.

[GlueBall]

Not all taxiways are equal width, the yellow line is just a guide denoting pavement center relative to the turn radius. If your airframe is a long tube, at some airports your outboard mains could clip an edge light if you were to keep the nose wheels on the line in a turn.

[capt. solipsist]

it is documented in airbus fcoms, it is called the oversteer technique. there are also figures in how much asda you eat up for different line up techniques.

[Capn Bloggs]

It is not uncommon for runway performance charts to specify the line-up manoeuvre used for the relevant calculations.

Not Uncommon? Every crew should know what their RTOW charts use as the lineup allowance.

[BOAC]

Every crew should know what their RTOW charts use as the lineup allowance.

It would appear some may not?

[320 driver]

Taxiway clearance is defined in the license for most UK aerodromes and for most the geometry must guarantee that gear remains on the defined surface with either pilot over the yellow line for all types approved for the aerodrome, so you can usually rely on staying on the concrete if you follow the lines.

A full 90 degree turn on is, IMHO, counter productive. Extra tyre wear/damage, more torsional stress for gear (especially on bogey types) and as anyone who operates out of LHR or LGW will know a very, very high price in occupancy and thus capacity/congestion. The risk of coming to grief on account of 10-20m? I would say miniscule.

I use and train that a comfortable moderate turn typical of a 90degree turn on a large taxiway does the job.

As for those who seem to be doing the shocked maiden aunt act at those who don't know the exact line up allowance, it would be worth taking a realistic view that there is a mountain of information that is far more likely to hurt you through ignorance. Claiming that accurate knowledge of this figure is some kind of absolute is ridiculous, concentrate on the stuff that kills people every year.

[good spark]

777
if you do a 90 on to the centerline are you sure the gear on your type can stand that? ( triple axle truck beams) how long are they, please tell me




gs

[DERG]

Something to think about...

Anyone any idea just what the forces are on the main gear when you do a turn like that?

"A full 90 degree turn on is, IMHO, counter productive. Extra tyre wear/damage, more torsional stress for gear (especially on bogey types) and as anyone who operates out of LHR or LGW will know a very, very high price in occupancy and thus capacity/congestion. The risk of coming to grief on account of 10-20m? I would say miniscule."

An understatement.

[de facto]

DERG,

counterproductive?Boeing disagrees with that for sure and so do I.
increased tyre wear?thats funny!
Taxiing fast yes i would agree would wear the nose tyre (737) but a properly made 90 turn(proper speed with thrust idle) would do nothing to your tyre.
However using improved climb speeds and rejecting at V1,will get you off the end,that day you may have wished to saved these precious meters as recommended by Boeing....

[ImbracableCrunk]

I think the nose wheel would be fine, but a double or triple bogey would grind a few wheels, I should think.

[DERG]

de facto

You misunderstand. I mean the TWIST forces and the MAIN GEAR. The nose gear is not the issue.

See what I mean?...the diameter of the wheel sets are not that great in comparison to say the total load of 400 plus tonnes shared across the set.

Think Lufthansa had a failure other week on a B74 at FRA. The main gear struts take a HELL of a twist load. Bally dance pirouet stuff. See?

In fact it would be interesting to learn how FedEx adresses this issue at Memphis. I would bet they use nice big arc turns...

[320 driver]

increased tyre wear?thats funny!

Can you confirm that you actually believe that such a turn will produce no tyre wear. If so I am astounded.

A sharp 90 degree turn WILL produce tyre wear on any type since the inside wheel will be rotated to some extent about its contact point and will scuff just like a car tyre when doing a low speed turn. On a bogey type there is also a substantial sideways force on the wheels as the bogey turns (Boeing officially recognise this). Perhaps an idea to check the technical details before you laugh.

[de facto]

UNHOOKED,

TODA line up is based on the main gear from start of runway not the whole fuselage.
ASDA line up is based on the nose gear.

Ill leave the twisting issue for maintenance,and will continue to follow Boeing takeoff safety guidelines.

320 driver,
i thought funny not to consider 90 turn because of increase tyre wear,fast taxy for example will increase tyre wear by much more.

[320 driver]

i thought funny not to consider 90 turn because of increase tyre wear,fast taxy for example will increase tyre wear by much more.

Where have you found this information. It sounds dubious to me as I always understood tyre wear when taxying in a straight line is negligible. Remember being told in tech course for ATPL that braking and turn were the chief cause of tyre wear. Can you confirm the source of your information.