TORA greater than ASDA????

[fastidious bob]

In my part A it states that only 2 RVRs (touch down and midpoint) are required for take off if the TORA exceeds the ASDA by 2/3.
How can the TORA be greater than the ASDA?This surely must be a misprint?Or am I missing something?

Thanks

F

[I Just Drive]

You sure its not ASDR (required) not available. That would make more sense. I only ask because we have the same rule but noone knows how to calculate ASD required.

[Ringi]

Not too sure. It would make more sense if it read ASDR.

[OverRun]

Accelerate-stop distance available (ASDA) defined as the length of
the take-off run available plus the length of any stopway. TORA cannot be greater than ASDA. Misprint.

[Squealing Pig]

Sounds like a mis print to me too, the last third can be 75m if the last third will not be required for a rejected take-off.

[fastidious bob]

I Just Drive,

On closer inspection it is ASD not ASDA, however, I still don't have a clue how to work this out. Would be nice to know, anyone?

Regards,

B

[rudderrudderrat]

Hi Bob, Depends on how your performance data is presented. Do you have generalised performance figures so you could see if you could take off OK from a runway that's 2/3rds of your TORA?

Our performance is lap top generated so it's easy.

[fastidious bob]

Hi Rudderrudderrat,

As line Pilots we do not have laptops, however our OPS department do. I think the best way to tackle this problem would be to ask them to work it out. I have a feeling the response I would get would be “COMPUTER SAYS NO"

[Okavango]

Are you sure it's not referring to TODA? This can be greater than ASDA?

[Squealing Pig]

fastidious bob, if you have electronic manuals would you be able to post the exact wording of the section in your pt A?

[fastidious bob]

ASD vs TORA
When the take-off run available (TORA) exceeds the calculated accelerate-stop distance (ASD), then only the number of RVR values relating to the ASD must be at or above those required in the table above.
E.g. ASD 2000 m, TORA 3000 m: only 2 RVR's must be at or above take-off minima. The RVR for the initial part may be replaced by Commanders assessment, but not in the 125 m take-off case.

[shlittlenellie]

Calculated ASD=required ASD (for given conditions)=physical distance that will be used.

Hence if the Take Off Run Available (physical tarmac available) exceeds the required ASD then only the relevant RVRs need be taken into account, i.e. if well airborne by stop-end (in the case of TORA>>calculated ASD), stop-end is irrelevant.

The 125m case can now include pilot assessment if the touch-down RVR is missing - according to newly issued Jeppesen 600 pages.

[Squealing Pig]

When the take-off run available (TORA) exceeds the calculated accelerate-stop distance (ASD), then only the number of RVR values relating to the ASD must be at or above those required in the table above.

Bit of a different way of saying whats in our Pt A :-

When the last third of the runway is not required for rejected takeoff
performance purposes, a minimum RVR of 75 metres must be
available in that segment.

[microbus37]

It is possible. Check for "negative stopway" and RESA.

[john_tullamarine]

Bit of a different way of saying whats in our Pt A

I don't think so - each is saying that the ASDA exceeds the ASDR albeit one tries it with some numbers to indicate the amount of fat .. one could have expressed the matter in a somewhat simpler fashion.

For the first post, read ASDR instead of ASDA.

[goeasy]

Isn’t it just logic.... if your ASD is only two thirds of runway, then the RVR in the last third is irrelevant...... because you’ve stopped or are airborne