Wake Turbulence Separation - Reciprocal Runways

[Prop Job]

Good day,

Imagine a situation where an MD-11 takes off from RWY36 and next in line is a B737 taking off from RWY18. Is there a requirement for wake turbulence separation in this case?

The only requirement I can find in Doc 4444 is for an aircraft making a low fly-by or go-around from RWY36 in this example, before the B737 takes off from RWY18.

Also, I have heard some controllers mention that there is no wake turbulence separation requirement when the x-wind component exceeds a certain value. Again I have been unable to find any reference. Can anyone confirm if this is the case?

Many thanks,

PJ

[Gonzo]

In the U.K. wake separation applies if the airborne tracks will cross, so I would suggest that it would depend on the rotation point of the MD11.

I'm not aware of any current method of reducing wake separation due to crosswind that's in operation.

[B2N2]

Technically wake doesn't start till the rotation point.
So for the sake of the discussion we have a 10,000' runway.
MD-11 takes off 18 and rotates at the 6000' marker.
The 737 would have to rotate and be airborne well before the 4000' marker in order to cross paths.
Assuming a no wind condition.
Now the MD11 taking off with a max legal tailwind changes the dynamics but it also changes the rotation point.
The 737 taking off into the headwind would still not encounter the wake.
Try drawing it if that makes any sense.
If we're talking about a 14,000'+ runway and light take off weights you might be able to make it work.
Now a light GA airplane is a completely different story.
And the ATC controller still doesn't make your decisions for you.
If you don't like it you don't go.

[Romeo_Fox]

UK Cap 493 9G. Departures – Opposite Direction
9G.1 A380-800. A wake turbulence separation minimum of 3 minutes shall be applied between a Light, Small or Medium (Upper and Lower) aircraft and an A380-800 aircraft when the A380-800 aircraft is making a low or missed approach and the Light, Small or Medium aircraft is:
(1) utilising an opposite-direction runway for take-off; or
(2) landing on the same runway in the opposite direction, or on a parallel opposite- direction runway separated by less than 760 m.
9G.2 Other aircraft categories. A wake turbulence separation of 2 minutes shall be applied between a Medium (Upper and Lower), Small or Light aircraft and a Heavy aircraft, and between a Medium (Upper and Lower) or Small aircraft and a Light aircraft whenever the heavier aircraft is making a low or missed approach and the lighter aircraft is:
(1) utilising an opposite-direction runway for take-off; or
(2) landing on the same runway in the opposite direction; or on a parallel opposite direction runway separated by less than 760 m.

[Gonzo]

Romeo Fox, the OP was after departure following departure from opposite ends, not departure following landing/missed approach.