Where exactly can you set take off thrust?

[Screwballs]

Hello,

Just discussing this the other day with a colleague and he wondered when precisely can we set take off thrust on a commercial airliner?

So did a bit of reading and wondered what other people might have to say. And also wonder what people think of real-world examples.

According to Jeppesen Text Manual and CAA CAP 168, page 286; Yellow Chevrons means not suitable for use by aircraft except as a stopway. However, in LGW 26L, the Yellow Chevrons are obscured by large white arrows.

The large white arrows are fit for the movement of aircraft according to 168. So we can set take off thrust all the way up to the edge of the yellow chevrons? But not on the yellow chevrons.

However, for some discussion, if you look at Dusseldorf via Google Earth the white arrows stop someway short of the actual tarmac. Now, purely being theoretical, if I entered any runway in DUS I could taxi onto the white arrowed area and set thrust but not on the unpainted/unmarked surface? That seems sensible.

And in another example in FCO, runway 25, preferred departure runway things are less clear. The threshold starts to the left of the the western holding point. And there are no white arrows or yellow chevrons. Where would be the right place precisely to set take off thrust? For example in FCO, the inbounds usually taxi down D or C which is right behind the 25 departure threshold.

I'm interested in what people think, and it's mainly to see other points of view on it.

Regards,

Screwballs

[rudderrudderrat]

Hi Screwballs,
I can remember this incident http://www.aaib.gov.uk/cms_resources.cfm?file=/Boeing%20737-436,%20G-DOCT%2006-07.pdf

Since I have very rarely needed to use TOGA power for take off performance reasons (Flex or assumed temp mostly), then there is plenty of stop margin in the calculations, and a rolling take off is the norm.

On the occasions that I have needed to set TOGA power against the brakes, then we never lined up as G- DOCT did.

[compressor stall]

Without knowing the runways concerned, look at the runway length on your performance charts and cross reference that with the RDA / ASDA.

That will show you your answer.

[flarepilot]

at san francisco, the question was the same...answered when sign was posted:

takeoff thrust from this point. or something like that...had to do with cars driving near threshold of one left/right and location of blast fence.

threshold marks make sense so use that.

[john_tullamarine]

Keeping in mind that the threshold markings generally are dictated by landing rather than takeoff as I understand (caveat - not an airports engineer).

With any luck, Overrun (who is) will come into the discussion and set us right.

[Basil]

Recollect following another aircraft at GLA which, as it turned onto the runway and applied power, detached a couple of large slabs of tarmac which tumbled off downwind.

[EEngr]

Perhaps the intent is to prevents scenes like this:

K2IB54jb3tc

[Basil]

EEngr, Yes, flew B747s in there a few times. Silly people - could wreck their eyes and, although there's a wire mesh fence, a lump of paving in the face could seriously offend :ooh:
Or perhaps I'm just an old, risk-averse, joyless barsteward :p

[Screwballs]

Cheers for the replies. It is a bit more of an obscure question!

The AAIB report is fascinating. Very useful food for thought for a contaminated runway, TOGA departure with ice accretion (ie run ups before the roll to shed blade icing) situation.

Out of curiosity, where is the eastern most point you would set thrust departing off runway 25 in FCO?

Thanks,

Screwballs