Departing from a taxiway / TO performance
 

Hi all,

A bit nit-picking maybe, yet I can't figure out the exact answer from the books.

Imagine a runway without displaced threshold but with a taxiway leading straight onto the runway (entry angle 0) two examples FCO 25 and MAD 36R

I always though you have to physically move the aircraft over the threshold before applying TO power in order not to take off from the taxiway = as they are not inspected the same way as the runway for FOD for example.

However when I looked at the TORA in LEMD 36R full length vs Y2 I see a different of 45m even though both of the taxiways lead you onto the same threshold (even though Y2 shows entry angle of 90 it joins the runway well prior the threshold)

Was my assumption about taxiways vs displaced threshold always wrong, or indeed, the 45m for take off from Y2 are subtracted for the 90 degrees turn even though it take place prior to the actual threshold?

There are no published lineup allowances for lead on 0 degree taxiways, hence probably using the shortest one, 90 degree, makes sense

The point is:

LEMD TORA

36R 3500m
36R Y1 = 3500m
36R Y2 = 3445m

The threshold 36R is definitely past Y2

http://www.aena.es/csee/Satellite?bl...&ssbinary=true

so I don't think you'd be loosing 45m lining up from Y2

Conclusion you are expected to start your takeoff roll from prior crossing the THD?

RWY 36R 3500m
Y1 3500m (considered full length)
Y2 3445m / 11302ft
Y3 3345m / 10974ft

Maybe this is of help...

LIDO Legends and tables:

Certainly during my line training I was told by more than one TC that the aircraft should be taxied from these types of 'start points' before commencing the actual take off roll.