T/O Separation in U.K. ?

[aiming point]

Have tried a search but no luck.
Can someone please provide the written source/reference to the 1 min take-off separation requirement for a Heavy behind a Heavy at LHR etc.
Our FOM and Route Manual say 2 min and I would like to have them notated accordingly should it be necessary.
Thanks for any help.

[cossack]

Take a look at

http://www.ais.org.uk/uk_aip/pdf/aic/4P188.pdf

You'll need Acrobat Reader to read it, but all your vortex wake questions will be answered!

[Dan Dare]

Why wait a minute?

There is no laid down requirement for vortex separation between heavies (in practice it would be difficult to see the leading aircraft airborne, clear the following one, have them spool up and airborne in less than a minute).

Please also note that there is no requirement to provide votex separation for a landing aircraft against a departure, nor a departure against a heavier landing aircraft as various pilots have suggested in the past.

[cossack]

DD
Agree with point 1.
To clarify point 2: If the landing threshold is displaced and the projected flight paths will cross, you do need to provide vortex wake separation. Otherwise, no vortex wake separation required.

[aiming point]

Thankyou for taking the time to reply.
Cheers.

[Gonzo]

Just to clarify, the 'one minute' between Heavy/Heavy or Med/Med isn't for vortex purposes, but for route separation. Generally, if the SIDs diverge after take off by more than 45 degrees, then it's one minute, if not then 2 mins.

However, in practice the 1 minute is often what we call 'wheels up', ie. as soon as the preceeding a/c is off the ground, no.2 is cleared for T/O. If you've got M/M/M/M/M/M then it works out as 50 seconds so in effect you gain time, and visual separation is used. If the wx isn't good enough to allow for visual separation, then I usually wait a few seconds before launching the next to ensure the 1 min. If you've got H/H/H/H/H then it usually works out to 65-70 seconds between each, so you 'lose' time.