Wake Turbulence Question for UK ATC

[MightyGem]

Is the recommended separation between aircraft that you give out, to the following aircraft, advisory or mandatory; ie, can a pilot choose to ignore it if he so wishes?

Helicopters are largely unaffected by it. In 30 years the only wake turbulence I've encountered is from another helicopter.

We recently started to operate our Police helicopter from an airfield where ATC absolutely refuses to lets us depart until after the required number of minuets have passed. We have several things in our favour: A, we are about 100m to one side of the runway; B, the prevailing wind is blowing the vortexes away from us; C, we are not following the preceding aircraft and will quickly be above and turning away from it's flight path; and as I've mentioned, it doesn't really affect us.

Are ATC legally obliged to make us wait or is it a case of their airfield, their rules?

Our Chief Pilot will be discussing the matter with them in a couple of days, but we just want to get our facts right.

Thanks

[Crazy Voyager]

Now I'm just a mere wannabe (hopefully a Trainee ATCO soon though, pending medical).

Anyway, this is out of CAP493 (section 1, chapter 3, page 12, at the bottom):
"ATC shall apply the minima as prescribed above, irrespective of any pilot
request for reduced wake turbulence separation. ATC does not have the
discretion to reduce wake turbulence separation minima."

I belive this means nothing will change after your meeting since the MATS is the founding document for ATC in the UK. But I do off course understand that you might want some real ATCOs to confirm that aswell :)

[Spitoon]

It's a few years since I worked for real and I don't have the references (or time) to hand to check.

But as I recall it depends broadly on your flight 'rules' for arrivals. If you are VFR or making a visual approach you will be given the recommended minimum spacing from the aircraft in front. It's up to you to arrange the spacing that you want. If 'full' IFR, ATC will give instructions to assure the minimum spacing exists. Some airports seem to have procedures which permit the spacing to be eroded inside 4 NM from touchdown but I don't think this is part of the national rules.

For departures the minimum spacings for take-offs apply to all aircraft irrespective of anything.

Of course, as you fly a helicopter things get more complicated. As I recall, if you are using the runway you get the same spacings as fixed wing aircraft. If you are using grass alongside the runway you get treated like you were using the runway (I can't remember whether this was just at the airport I last worked at or in the national rules) and if you were using another part of the airport we just take lots of care and exercise individual judgement.

At airports with lots of heli ops - especially big ones - you'll probably find local procedures are developed for common operations. The national rules are in the Manual of Air Traffic Services Part 1 (CAP493) available on the CAA website.

I think this is all roughly right but hopefully someone current will be along before your CP's meeting to either confirm or correct the above.

[ADIS5000]

MightyGem,

The reference you need is CAP493 Section 1, Chapter 3, Page 12, Para 9.6. (Google it.)

I work at the Scottish airport with all the helicopters (!) and basically it is a mandatory requirement that departure wake turbulence is applied by ATC. The lateral distance you mention of 100m is nowhere near enough. You need to be displaced by 760m or more. If you are arriving as VFR then the spacing given to you by ATC is only advisory.

At my unit we are fully aware that helis do not feel the effects of wake turbulence as much as fixed wing but as no one has done any definitive research to prove this then the CAA line is that the above reference is to be applied.

Wish your CP good luck but I wouldn't hold your breath. If you do get anywhere please let us know though!

Regards, ADIS

[MightyGem]

CAP493 Section 1, Chapter 3, Page 12, Para 9.6.
Yeah, suppose that says it all really. Although when we operated out of Liverpool, they were happy to let us go, and so was the guy I spoke to there today.

Thanks for the info everyone.

[Danscowpie]

Wake turbulence distances for arriving aircraft are recommended.
Wake turbulence separation for departing aircraft is mandatory.

Helicopters are largely unaffected by it. In 30 years the only wake turbulence I've encountered is from another helicopter.

Complete and utter nonsense, helicopters are just as at risk from the effects of wake turbulence as fixed wing, in fact, due to the reduced time a helicopter piot has to react to and recover from such an issue compared to fixed wing, it's even more important that the departure separation is applied.There are absolutely no facts to suggest otherwise.

At my unit we are fully aware that helis do not feel the effects of wake turbulence as much as fixed wing

I refer you to the above and challenge you to present the evidence.

But as no one has done any definitive research to prove this then the CAA line is that the above reference is to be applied.[/

Yes they have and yes they are, EASA are conducting a major study into the turbulent wake effects and have been doing so for a number of years. All sectors of industry are being consulted, Helicopter operators throughout Europe and ATS Managers in the UK were the first to be asked to contribute, although not many of the latter considered it worthy of reply.

[HEATHROW DIRECTOR]

<<Wake turbulence distances for arriving aircraft are recommended.>>

Guess another change since I hung up my electric hat. At Heathrow, wake turbulence spacing on final approach was mandatory and if it was not achieved, the Air controller was bound to break off the second aircraft or switch it to the other runway if poss. I'd be interested to know the rules now.

[BEXIL160]

Oh dear,


Helicopters are largely unaffected by it. In 30 years the only wake turbulence I've encountered is from another helicopter.

A statement of the poster's (a helicopter pilot) 30 years experience. Kind of relevant I would have thought and useful to the debate.

but...


Complete and utter nonsense, helicopters are just as at risk from the effects of wake turbulence as fixed wing, in fact, due to the reduced time a helicopter pilot has to react to and recover from such an issue compared to fixed wing, it's even more important that the departure separation is applied.
... and this is based on?

There are absolutely no facts to suggest otherwise Really? See quote 1, above. At least one experienced helicopter pilot might suggest otherwise.

I might suggest that Helicopter pilots are also a lot more aware of local wind effects and have better SA all round. They need to have.

Wake vortex is indeed poorly understood, and I know of several occasions where it has clearly contributed to accidents to fixed wing aircraft. Not sure I recall any affecting helicopters though... Enlighten me.

BEX

[terrain safe]

Bex

Perhaps the heli pilot hasn't been affected because he has been separated by ATC? Therefore no wake turbulence to be affected by.

Just a thought.

[BEXIL160]

Possibly, but he alludes to the fact that some ATCUs have been "flexible".... and I know that some units not subject to MATS part 1 do (did?) have different guidance for helicopter departures.... and they don't have a record of wake vortex encounter incidents.

BEX

[MightyGem]

Perhaps the heli pilot hasn't been affected because he has been separated by ATC?
More likely because of our steep climbout we avoid any wake turbulance. I've departed many times within a minute of 737s and such like without any problems. As I said, I have felt it behind another helicopter(and from my own at times when orbiting), but it's just like driving over a bumpy road. I admit it could be different in an R22 or suchlike.

[Bagheera]

HD, think you might be slightly misinterpreting what was being said. If a controller is vectoring aircraft onto final approach then the wake turbulence seperations are mandatory for the controller to achieve, otherwise the aircraft should be broken off the approach. What is meant is that if an aircraft, whether VFR or IFR is conducting a visual approach then the controller will pass the recommended spacing and it then becomes the pilots decision to achieve or not that recommended spacing.
Dont suppose there are many visual approaches carried out at heathrow most days. :O

[Gonzo]

MightyGem,

At Heathrow we've successfully argued that the 760m value does not apply to helicopter operations. We operate a helipad 250m from our southern runway independent from any vortex (apart from Super Heavy category a/c).

We used ICAO documents (can't remember off hand which one!) where that 250m figure came from (from the edge of a Code E Runway). Our runways are Code F, so hence why we still apply vortex from A380s.

PM me for more info if you wish.

[2 sheds]

Danscowpie
Wake turbulence distances for arriving aircraft are recommended.

Very misleading. I hope that you qualify that in practice!

2 s

[Lon More]

until after the required number of minuets have passed.
So whereabouts are you, in a ball room? :}