wake turbulence sep during takeoff

[galleypower]

Under what circumstances may ATC reduce the standard 2 or 3 minute separation between departing aircraft?

and...if I depart in VMC conditions but on an IFR flightplan, who is responsible for maintaining separation? The pilot or the controller?

Many thanks

[Gonzo]

in the UK, ATC cannot under any circumstances reduce departure wake turbulence separation.

Your second question implies you're interested in all forms of departure separation, not just wake turbulence, correct?

[galleypower]

Thanks for your answer. Good to hear that it is applied so strictly in UK. I noticed that things are different in e.g. Frankfurt. Does anyone have info how the rules are applied outside of UK?

And regarding the second question, I am only interested on wake turbulence seperation (at this moment).

[mad_jock]

depends what type as well.

The ICAO medium goes from 7 tons all the way up to 100.

The UK splits it down further with 7 to 35 tons(?) counted as a light. Which is much more sensible.

Some countrys will give you "caution wake vortex, cleared takeoff"

And others will give you gip for not accepting a departure 30 seconds after a 757 in your crappy turbo prop in still wind.

The only way you can cover your arse is by telling them you want it when you pick up the clearance and then remind ground on the way out if you get put behind something scary.

It can get confusing if your flying a lower end medium in the UK then cross the channel to discover that your now in with the big boys. You do it once or twice with a reasonable crosswind and everything is OK. Then you get caught once and after a change of pants vow never to get caught again. Its always worth coming down one dot high on the ILS in europe anyway when its not LVP's to avoid wake vortex if they are running them in min spacing then land after where the one in front lands. Once LVP's are in they increase the spacing so its not an issue.

Normally this only ever becomes an issue at multiple runway airports as one landing one departing takes care of it for single runway ops.

[Gonzo]

It is ATC's responsibility for wake turbulence separation on departure, regardless of flight rules or met conditions.

[mad_jock]

Gonzo different countries have different ways of doing things even in europe. And if your used to the Brit way of doing things it can be a bit of a shock on first exposure to the way the rest of the world works.

And it is also the PIC's job to conduct a safe flight so if they want more than the book says thats what the get. Obviously its bad form to announce you want more just as you block the runway or for that matter once you are in the line up sequence. For that matter some company SOP's state you need more behind certain types than the official book figures 757 being the prime example.

Min spacing behind something 3 or 4 times your weight in the medium cat can be a bit of a rollercoaster.

[DaveReidUK]

The UK splits it down further with 7 to 35 tons(?) counted as a light.


Close. In the UK, the demarcation between Small and Medium is 40 (metric) tons.

[mad_jock]

Thanks and what a sensible idea it is to.

[galleypower]

Thank you all for your answers. Flew today out of two German airports. I got takeoff clearance twice well below the standard separation of 2 resp. 3 minutes. Could it be that the controller takes the aircraft size/performance into account? But how does he/she know the load resp, the performance of an aircraft?

1st case: line-up and takeoff behind Embraer 190
2nd case: line-up and takeoff behind B737

me in Embraer 135...(20 tons)

[ron83]

The ICAO medium goes from 7 tons all the way up to 100.

Up to 136 tons to be correct.:ok:

[Jamieh]

They base it on your MTWA. In terms of WT departure separation Medium and Small are the same category, so in your E135 (small) there is no WT departure separation required behind an E190 (medium) or 737 (also medium.

[Tower Ranger]

FWIW in my part of the world you would be considered the same Vortex wake category, medium. So as long as you were departing on diverging tracks you could be given take off once the previous departure was airborne and at least 2500 metres down the rwy, aprox 45 seconds.

[rodan]

Galleypower - I can't speak for ICAOland, but in the UK you would have received no wake turbulence separation in either of the two situations you describe. An E135 is categorised Small in the UK, both the types you were following are Medium. No departure wake turbulence separation applies between these categories.

[mebur_verce]

Same where I work (Italy): an E135 being in the same Wake Turbulence Category (Medium) as an E190/B737, no wake turbulence separation would be required, unless you were departing from an intersection further down the runway.

[mad_jock]

http://www.skybrary.aero/bookshelf/books/1166.pdf

This is quite good for the differences to ICAO and the rules.

http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-OPS_ENV-SEQ07.pdf

This isn't bad either.

[DaveReidUK]

http://www.skybrary.aero/bookshelf/books/1166.pdf

This is quite good for the differences to ICAO and the rules.


That's the 2009 edition, superseded by this one in 2010:

http://www.ead.eurocontrol.int/eadbasic/pamslight-785A283B263BD599EE5A0C2AF80B43B0/7FE5QZZF3FXUS/EN/AIC/P/072-2010/EG_Circ_2010_P_072_en_2010-10-07.pdf

though as far as I can see, the only differences are in the helicopter procedures.

Both editions have the same wonderful note at the bottom of Page 5.

[fujii]

Australia: Up to 7000 kg - light, >7000 - <136000 - medium, 136000+ heavy. Medium less than 25000, no wake turbulence separation behind required for a light.
A pilot may initiate no wake turbulence separation using the phrase "accept waiver" but ATC must include "caution wake turbulence" with the TKOF clearance. Due to their wake turbulence characteristics, a 757 must be treated as a heavy if leading and a medium if following.

[Talkdownman]

Dave's link not working for me.
Try this AIC: P 072/2010 (http://www.ead.eurocontrol.int/eadbasic/pamslight-7A881E823DFA2748A8124F4B46B643AF/7FE5QZZF3FXUS/EN/AIC/P/072-2010/EG_Circ_2010_P_072_en_2010-10-07.pdf): All you need to know about UK Wake Turbulence Weight and Separation Criteria.

[scotbill]

Surely Xwind component should allow some modification of standard separations to increase RW utilisation?

As I remember it the worst case is a 5kt cross wind component which can hold the upwind vortex on the runway.

Conversely, stronger components would clear the vortex very quickly - but might pose problems for a parallel runway.

[Dan Dare]

I believe CREDOS (http://credos.bluskyservices.com/) is expected to answer this. I don't really believe it to be a good idea with my loved ones on board.

[Gonzo]

Mad jock,

Sorry, I thought it was clear after my initial post that I was referring to the UK.

[mad_jock]

:ok: So was I, its both ATC and the PIC.

[Gonzo]

Now I'm confused. I thought we were talking about reducing departure wake turbulence spacing, which ATC is responsible for providing and cannot reduce.

If the crew want more than required, that's fine. If the crew are happy with less, then ATC will not permit that.

In the UK of course.

[bigjames]

are there different requirements for landing... ie what if you follow a larger aircraft in... i have been given "caution wake turbulence on approach but up to me to judge distance. (was smallest aircraft in the sequence by far)

[mebur_verce]

are there different requirements for landing... ie what if you follow a larger aircraft in... i have been given "caution wake turbulence on approach but up to me to judge distance. (was smallest aircraft in the sequence by far)

Were you (and the preceding traffic) flying VFR or IFR?

[bigjames]

preceeding IFR, me VFR

[ZOOKER]

The current CAP493, (MATS Pt. 1), states that:-

Separation standards are minima and shall be increased when:

a) requested by the pilot;

b) the controller considers it necessary;

c)directed by the CAA.

[mebur_verce]

preceeding IFR, me VFR

That sounds pretty normal to me.

"Join final rwy xx, number two, preceding A320 medium [position], caution wake turbulence" or something like that is all that's required when a VFR follows a medium or heavy IFR.

From ICAO Doc 4444:

http://i.imgur.com/Pcc46.png (http://imgur.com/Pcc46)

[bigjames]

many thanks zooker and MV.

that is how i understand it as well.

but wonder if (all else being equal) i should be leaving more separation on landing compared to take off. ie is wake turbulence worse on take off or landing? are tip vortices more a function of thrust or flap config?

cheers

[Tarq57]

but wonder if (all else being equal) i should be leaving more separation on landing compared to take off. ie is wake turbulence worse on take off or landing? are tip vortices more a function of thrust or flap config?
I think if you're flying a light, and the preceding is a heavy, there is probably little difference - in practical terms - between the turbulence generated during initial climb vs approach.

Flaps will tend to break up the turbulence slightly. Vertical component of engine thrust will reduce wing loading slightly. We're only talking a few points of a decimal-place percentage, though. In practical terms, you don't want to be caught in either.

Landing is generally easier to avoid, by staying above the approach path of the heavy, and touching down beyond the heavy's touchdown point. Note that a tailwind will effectively reduce the margins. Maybe cancel them out altogether.

In NZ (fwiw) a pilot is permitted to take reduced wake separation on departure. This happens fairly often. Usually when the medium is a fairly light-ish sort of medium, such as a B190 or SW4.

[bigjames]

thanks! appreciate the answer!:ok:

[FlightPathOBN]

Link from the FAA ATC 711.65 Section 9. Departure Procedures and Separation (http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0309.html)

I am thinking that the bare min, and I mean bare min for ICAO DEP distance is runway length +1000 feet. (but cant remember exact)

Any Heathrow controllers here involved with the time based separation simulation testing?

[west lakes]

As an aside I witnessed this sequence earlier today.

A 380 land, B 738 take off, PA 28 take off. From one extreme to another!

[Fesch]

Hi WL,

This is not an unusual sequence, at least where I work (You'd have to replace the 380 by a 747 though).
There is no WT separation between the landing 380 and the departing 738.
So i'ts only a WT sep. between the Medium 738 and the light P28A, which is 2 or 3 minutes depending on wether they departed from the same intersection or not.

[Gonzo]

FlightPathOBN,

What do you want to know about TBS?

[FlightPathOBN]

Gonzo..will PM

[1Charlie]

At Australian 'RADAR' towers aircraft can roll using radar derived distance based wake turbulence separation which you often achieve prior to two minutes.