Take-off alternate performance requirements

[president]

This is a planning question only! For large jets in Europe, would your take-off alternate have to comply with the ability to stop within 60 pct of the required LDA? I have checked the docs and cannot find anything to suggest otherwise.

And another thing. Take-off with eng failure. On return to dep airport SE you can only stop within 80 pct of the LDA. In the planning phase do we need to nominate a take-off alternate that complies with the 60 pct ?

[B737900er]

Simple answer is yes. Its a Performance A requirement.

[president]

According to EASA:

"The landing mass of the aeroplane determined in accordance with CAT.POL.A.105 (a)
for the estimated time of landing at the destination aerodrome and at any alternate
aerodrome shall allow a full stop landing from 50 ft above the threshold:
(1) for turbo-jet powered aeroplanes, within 60 % of the landing distance available
(LDA)"

This would imply that this planning requirement is only present for destination and any alternates. But the departure airport is neither. So to put it short any take-off alternate will comply but not the departure airport if we return immediately (as its not a destination or alternate). Right?

[FE Hoppy]

clue is in the question.

Take-off alternate.

[president]

It's settled that we need the performance margin for the take-off alternate. But what about return to departure airport. That's not an alternate. According to the docs I could find we don't need that margin in the planning phase (as it's not an alternate)... Question was if there is anything out there disputing that ?

[president]

Unless "any alternate aerodrome" is to be regarded as "any other" airport, which would include the departure airport?

[Derfred]

I've never heard of any requirement to assess the departure airport for LDA.

I would guess that is because in virtually every normal scenario TODR > LDR.

So, to play the devil's advocate, what about a displaced landing threshold?