Supplementary take off distances

[Jay Bo]

Anyone can give an understanding on supplementary take off distances found in ERSA.

eg. Orange
RWY 29 TORA 1676 TODA 1816

Supplementary take off distance
RWY 29 1791

Does the above mean if you are taking off 29 at the point of entry from the taxi way the distance will be 1791 and if you use the full length from the turning node it will be 1816

thanks

[triton140]

1791 for 29 at YORG is based on a 1.6% obstacle gradient, 1816 is for 1.64%.

It's all explained at the front of ERSA under "Runway Distances Legend".

[Capt Fathom]

ERSA Intro page 21 & 22 explains it.

All to do with gradients after takeoff.

Just think of a 100ft hill right on the end of the runway.

If your aircraft can climb out at a 6% gradient, you can become airborne much further down the runway, climb out and clear the 100ft hill.

If you're in an aircraft that can only climb at a 3% gradient, you must become airborne sooner (ie in less runway) in order to clear the hill, as you are climbing at a shallower angle!

So you may see this in the ERSA or in Notams:

SUPPLEMENTARY TKOF DIST
RWY29 1500(6%) 1000(3%)

If you can climb at 6% you have 1500m available for takeoff.
If you can only climb at 3%, you have 1000m available.

PS.. also some further info here (http://www.google.com.au/url?sa=t&source=web&ct=res&cd=3&ved=0CBUQFjAC&url=http%3A%2F%2Fwww.casa.gov.au%2Fdownload%2Fcaaps%2Fdrome% 2F89o_1.pdf&ei=rgxVS9muOcugkQXLl6GgCg&usg=AFQjCNGjFHJgrjKSoxtrKYOJNuHs5QO8Kw)

[DeeJayEss]

Nothing like some takeoff performance and OCTG calculations to wash dinner down with!

[gupta]

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.