Runway Line Up Technique
 

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 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.

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

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!

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

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. :O 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.

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.

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. :eek:

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.

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

It would appear some may not?

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.

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

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.

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....

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

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...

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.

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.

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.

Nah not tyre wear
 

Tyres are cheap. The stress is on the members and wing roots. Hard turns are not good. Can happen quite fast in the life of the airplane. I bet Japan operators have these issues on the short hops. As well as the freight guys of course. See FedEx at Memphis.

With my operator 90 degree turns are limited to 10 kts max to minimise tyre wear (monitored by OFDM so no cheating!)

32o driver,

Flight crew training manual will give you such info about NOSE wheel tyre wear during fast taxi...(B737).

Concerning the line up thing,here is the copied info taken from boeing safety guide:
As i said i let the wear/tear for the airline to check, Im concerned about my flight,my passengers on the particular day.

FIREFLY<
On a 737/800-900, a 9 kts entry followed by a 6-7 knots turn will get you lined up without thrust.10 kts into the turn is bit too fast i think.

DERG, I agree that member/strut/root strain is a major concern. However, if your tyres are cheap can I have the name of your supplier. Although one wonders whether Air France still use cheaper retreads since the Concorde accident.

Haha
 

"line up and wait" hope the main gear is OK....

"line up and hold" hope the main gear holds up

320

That whole Concorde tyre thing was a JOKE.
As though Michelin was above making the proper tyre
which they could so easily have done. It was a French thing.

de facto

airbus give reference to tyre wear at high speed but specifically refer to turning at high speed as the issue.

An aircraft manufacturer does not have to take account of the commercial environment. A Captain does (or should) and any Captain who states that wear/damage issues are someone elses concern would be very unwelcome in my airline. Its your job to balance these issues not just take a blind view.

On a limiting runway I absolutely agree that one should maximise the TORA but on a generous runway operating well inside liimts (LHR27L on a moderate weight medium twin) there is NO EXCUSE for the additonal inconvenience/cost to others and your own airline.

NOt boeing, high speed taxi on a straight line will damage the side walls of the nosewheel.

If you give me the info every flight about this extra runway based on my calculated V1 (assumed thrust or not) (medium weight or not)and I will consider using the extra distance for line up..
I have other ways to save money to my airline but thanks.It seems Im excused as we are closely monitored....

No EXCUSE? THAT is funny:E

de facto
 

What brand tyres are used in China please?

Has Hankook got round to this yet.... or are they mostly Bridgestones?

Certainly better quality than those you use in your LOCO airline.:E

We get ours at the wreckers yard..

de facto

If you think it is acceptable to inconvenience others and cause delay and cost to them just because you aren't bright enough to work out when it is or is not appropriate to take a practical approach to your operation then I can only sigh with relief that you are not UK based. Please tell me you're not a Captain. That would be scary.

:hmm:
I am causing delay now?
I am well familiar with loco UK airports...never had any issue on my 'lenghy' costly line up method.
If im asked to expedite,i will...dont take me wrong...but a long line up followed by a stop and then a take off roll, i say N0.
Ill leave that to your superior UK captainship.

OH and i do this crazy stuff based on a UK caa issued ATPL...thats food for thought.:ugh:

I'm losing the plot here......this "LOCO" stuff is confusing me..

Here we go: "Loco is Crazy in Spanish"

Could be BA "speak" due to merger with Iberia?

:E

Or maybe LOCA....

I see....
 

A song?

http://en.wikipedia.org/wiki/Loca_(Shakira_song)

right....

seriously A320

If Im 3 T below my runway limit weight...how much extra stopping distance would that give me? 200m?100m?50m?
What about 4Tonnes?or 5T?
Does BA give you this info?

What if on that day,i were slower to initiate reject that day?(tired..)..how much these few extra knots convert into meters?

Yes we must balance between many factors, if im cleared for immediate take off, i will use shallow entry as thrust is increased during the line up which counteracts the loss of runway length./or shallower entry if runway is covered by snow or narrow runway...

But please get off your BA HORSE and keep your Captain worth recommendations for your cadets..:suspect:

Question
 

320 is off line...If there is doubt about runway length...why not

At the hold position...spool up the engine with the brakes on..then release say with throttle at 75%..

Or is this a big NO NO?

DERG,

Are you flying Jets?

at moment a Toyota Corolla until I get the Porsche insured..

jets are diff?

seriously...are jets diff to anything else?

are we talking jet blast behind here or what?

complaints from the tree huggers?

BA may have an issue with 90 degree lineups since the incident up in ABZ a few years ago.

http://www.aaib.gov.uk/cms_resources...CT%2006-07.pdf