Vortex Wake

[niknak]

I know all the regulatory applications etc of vortex wake, but I've often thought that if the surface wind is directly across the runway and is, for arguments sake, 15kts or more, the vortex wake should dissipate quicker than it would if the wind strength was 5kt.
I would be interested to know if the fine minds who research vortex wake issues have considered this as a factor and does anyone have any contacts therein?

I ask partly because we have heli ops (often cat A & B flights) which have to go at short notice and they operate from an area which is close enough to the runway to be affected by vortex wake by departing aircraft, as are both the helicopter training areas.
In the event of a vortex wake issue, the Cat A & B flights get priority and the departures are delayed, conversly the training heli's get delayed.

One of my OJT students who is ex Mil recently told me that if the crosswind component exceeds 6kts, in the Mil', vortex wake is not applied for take off purposes.
Is that correct?

[OCEAN WUN ZERO]

Wake

Heard this only yesterday from an ex mil visitor. Cannot believe that at BZ or Lossie or is it Kinloss they disregard Wake behind a c17 or NIM.

On a related issue a scenario.

Light, orbiting at the end of the downwind leg for a Medium arrival. due to priorities based on training vs. earning a living after the landing Medium one decides to depart 1 or 2 before considering bringing on the circuit traffic.
Question
When you do decide to bring it on do you need to take into account the dissipating vortex or not and if you do what RTF do you use????

[canard68]

It is correct about the 6kt crosswind and the time/distance values are approx half the civil numbers. I reckon the military would find civil wake vortex procedures too restrictive.

[Spitoon]

There's work going on - I think Eurocontrol's involved - to develop variable time-based separation techniques that take account of the dissipation (sp? doesn't look at all right!) of vortices.

[reportyourlevel]

Light, orbiting at the end of the downwind leg for a Medium arrival. due to priorities based on training vs. earning a living after the landing Medium one decides to depart 1 or 2 before considering bringing on the circuit traffic.
Question
When you do decide to bring it on do you need to take into account the dissipating vortex or not and if you do what RTF do you use????

You can't just ignore the vortex, unless you're sure that the time equivalent of recommended spacing has elapsed. If you're bringing the circuiter in before that time, then I would use this phraseology: "G-CD report final, number two, number one is a whatever landed at time XX. Caution vortex wake, the recommended spacing is Y miles." Of course, if the trainer was intending to touch and go, you'd still need to consider vortex from the departures you'd launched in between.

[OCEAN WUN ZERO]

Wake

"You can't just ignore the vortex, unless you're sure that the time equivalent of recommended spacing has elapsed."

Ok but unless Ive got early altzimers I dont know of the time equivelent of say "recomended" 6 miles being published anywhere. Could go for 3 mins but at some fields with airspace and ground maneuvering challenges this would be difficult to apply?

Point here is the airframe that produced the wake might be on the stand, so it would be Tfc WAS a 737 landed at X recomended spacing WAS etc etc etc... bit of a mouthful and not promoting brief and concise RTF.

[eastern wiseguy]

http://www.eurocontrol.int/eec/credo.../homepage.html


For info this is the project Eurocontrol is working on.

[niknak]

Thank you.

[reportyourlevel]

Ok but unless Ive got early altzimers I dont know of the time equivelent of say "recomended" 6 miles being published anywhere.

If you're in the UK: CAP 493 Section 1 Chapter 3 Page 12.

Edit: The rule of thumb is to divide the recommended distance by two then round up to the nearest minute.

[OCEAN WUN ZERO]

Mmmmmmm

"If you're in the UK: CAP 493 Section 1 Chapter 3 Page 12.

Edit: The rule of thumb is to divide the recommended distance by two then round up to the nearest minute. "


This could be used but may not pass the Grey Wig test.

Projected paths are not CROSSING they are following!! after some indeterminant time.
Or are we saying its the only tool and crossing behind = following in this instance. And as M followed by L = 3 mins anyway there is no issue.

Still