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Old 19th Jan 2010, 09:54
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gupta
 
Join Date: Jul 2006
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Published in ERSA, but it is raw data - not always apparent to the uninitiated. It used to be easier when Flight Service could help with briefings

TORA - Take Off Run Available - the physical length of runway available for takeoff. This may include an area before the commencment of the runway that is available for use.
TODA - Take Off Distance Available - the runway length plus any clearways etc after the runway proper ends. Normally there will be no obstacles under a 3.33% (IIRC) gradient from the clearway end unless published, in which case the TODA will be shorter than that for an unobstructed runway.
STODA - Supplementary TODA - calculated where there are any obstructions, so Supplementary TODA will be less than TODA unless there are no obstacles. This will allow pilots to calculate the available TODA against particular aircraft requirements such as a need for a 2%, or 1.5% climb gradient
LDA - Landing Distance Available - based on a 5% gradient to the touchdown point, so may be less than the physical runway length if there are obstacles in the approach.
ASDA - Accelerate Stop Distance Available - the distance from the start of the takeoff area to the end of any runway plus stopway if available.

Hope this helps. It used to confuse lots of people until they grasped the concept.

I worked with these figures for years as an Airport Inspector and now still can't forget it.

Even more relevant when runway works were in progress, with obstacles on the runway but some runway available.

If anyone wants more info, I'll try to work up some diagrams.
gupta is online now