line up allowance JAA A320
 

very well explained in grips with performance,

our laptop calculates t/o performance based on a 90 line up allowance
(i understand there is a standard one to correct for tora and asda and each operator must cater for their own, obviously in excess not in defect).

my inquiry

what is the purpose of the yellow line on line up?

i always continue straight ahead deviating from the yellow line as i did on the cessna 152.

thanks for listening

1. Taxiways have classifications so operators know which aircraft will fit onto them. As long as the aircraft's nose wheel tracks along the line the main gear will not go off the edge of the taxiway on corners.

2. In low visibility operations or night operations it may be difficult to locate the taxiway while on the runway. If you have a line going from the centre of the runway to the taxiway it's easier to find.

Generally the yellow lines are there to guide you when taxiing OFF the runway, so that you remain on the paved surface when entering the narrower taxiways.

Airports do sometimes provide taxi-on guidance for unusual layouts (there is one at ALC at the moment due to WIP), but normally it's up to you to line up properly.

We just use the standard values for A320/330/340 and even our Boeing aircraft.

Mutt

yellow line will not show up if aligned on wrong runway.