Acceleration stop distance on B777 ?

[skylark777]

Does anybody knows, how many meters a B777-300 would take after a rejected take off at heavy weight (345 T) ?


345 T - 15 Celcius - wind Calm - Sea level - Wet runway

Many thanks,
Skylark

[nitpicker330]

Well errrrr, mate that would depend at what speed it rejected at!!
10kts might take 10 feet
140kts might take 3 to 4,000' to stop perhaps? We don't calculate the figure anyway.....

[hetfield]

We don't calculate the figure anyway.....

I hope you do.....

[wiggy]

I hope you do.....

I suspect the point nitpicker is making is that whilst obviously the stopping distance enters the performance equations/calculations it is not a figure we specifically calculate for every takeoff or is made available to us for every take-off calculation......

That said you could use the normal or non-normal landing distance tables from the QRH to come up with a stopping distance - provided of course you knew the initial conditions ;)

[nitpicker330]

Huh?????

Mate mate mate. We calculate our T/O Data to either 1/ stop in the ASDA, or 2/ clear the end of the Runway by 35' ( 15' wet ) Engine out AND and then clear the obstacles in the t/o path. Thrust is reduced commensurate with conditions and weight etc etc,

It is assumed in those calculations we will stop by the ASDA BUT we don't know the actual distances involved!!

We get weights, thrust settings and speeds. That is all:ok:

[Fullblast]

That said you could use the normal or non-normal landing distance tables from the QRH to come up with a number of sorts - provided of course you knew the initial conditions


That's what I would do.

[nitpicker330]

How? Those figures are for landing with idle thrust at touchdown. How much extra would you use going from full thrust to idle??????

Anyway YOU DON'T NEED TO KNOW THE FIGURE. Follow your T/O Data calculations correctly and you "should" stop in the ASDA available :ok:

Having said that,,,,, have you ever seen a Boeing RTO?? The brakes come on really really hard and your shoulders hurt for days after from the harness!!

I imagine after quite a few years on the 77W that at 351 tonnes stopping at V1. ( around 150kts ) wouldn't take that much distance? Maybe 3,000' dry.

[de facto]

It is assumed in those calculations we will stop by the ASDA BUT we don't know the actual distances involved!!

How about for thrust setting for full rate or derate?(no Ass) and go in the take off field limit weight table to find the take off field lengh required?
You just need the thrust rating,temp,weight,slope,dry,wet...
A B737 uses about 60% to accelerate and 40% of the distance to stop.
Why cant the B777 be the same?

Tme to open your FCOMs again i guess:E

[plain-plane]

In my small 73, my EFB also gives me "stop margin", the calculated remaining distance of ASDA, after an RTO at V1...

Now if you are not quite happy with ASD with a zero meters margin, then you can change some of the inputs, and change your performnce to give you a better margin.... (on the EFB you can: short the runway from either end, increase the TOM by an approved amount, and a few other things)

There are often a range of V1 speeds available to you, and knowing on what criteria your company has selected for the prefered V1s on the EFB, gives you a good basis for changing the basic settings for your takeoff performance...

Ie: the EFB gives you go minded V1 speed on contaminated runways, and will generally avoid V1 speeds giving you 0 meters of stop margin...

[wiggy]

Anyway YOU DON'T NEED TO KNOW THE FIGURE.

Calm down, calm down, no need to shout - I think most of us agree with you with you.

How? Those figures are for landing with idle thrust at touchdown. How much extra would you use going from full thrust to idle??????

Again agreed, but it at least gives the OP an idea of some sort of typical stopping distance - I'm certainly not recommending it for passing Perf A or whatever it's called these day.....

[de facto]

In the AFM maybe then?:rolleyes:
You all have one on board?

[zlin77]

On the 77W we use OPT in the EFB, it calculates very precise T/OFF performance figures, normally it seeks to establish Improved Climb data, but will default back to Balanced Field if necessary...the actual stopping distance is not displayed to us for an abort at V1, but observing many Max Weight take-offs at 351 Tonnes, I would estimate that the V1 point leaves as little as 3,000-3,500 feet of runway left...on a dry runway, on a wet runway with V1 reduced by 11-14 its. I can only assume it might be 4,500-5,00 feet..

[skylark777]

Hi,

Many thanks for all of your answers.

My initial question was about, how to have in mind an order of magnitude of the likely acceleration stop distance, a Boeing 777-300 would need at full load.
(345 T, Full thrust, 15°C, Seal level, wet runway)
I had in mind, that a B777-200ER at roughly 200 Tons, would need at the same conditions listed above, 1300 Meters (4200 ft), right ?

As you know, the Boeing Laptop Tool, doesn't give this kind of informations.
One more time, I wanted to know this information just about a good "Situational Awerness" as nice to know !...

Best,
Skylark

:ok:

[FE Hoppy]

In our little Jet AOM we have ASD tables for low vis operations. The info is useful if you can show that the last 3rd of the runway is not relevant to the TO as it's rvr no longer needs to be taken into consideration.

I'm not sure there would be many cases where this info is useful on a 777. Certainly wasn't on the old 3*.

[mutt]

In the AFM maybe then?
You all have one on board? Chapter 4 of the B777 AFM is a digital performance interface, so unless you have a laptop you cant run it.

mutt

[de facto]

My initial question was about, how to have in mind an order of magnitude of the likely acceleration stop distance, a Boeing 777-300 would need at full load.

As i wrote earlier you either can find out by looking into your FCOM(where you get Vspeeds) under take off field lengh REQUIRED.

Or in the AFM and im quite sure the ASD is one of the graphs in it.

Are you a B777 pilot or not?do you have those manuals?.
I had in mind, that a B777-200ER at roughly 200 Tons, would need at the same conditions listed above, 1300 Meters (4200 ft), right ?
A B777-200(trent 892 engines) at 270T 30C,SL,flaps 15,will need 7820 ft asd with a balanced V1 and a 780 ft STOP margin.(toda=asda=9500m).
At 200t,about 4800ft for a balanced V1.