B757 Wake Turbulence timings

[brownstar]

I was always under the impression that the minimum time for seperation between a preceeding B757 take-off and a following medium aircraft, was two minutes. Is this the case or is it different for individual airports? I heard that this time can be as little as one minute. Answers from aircrew would be good but I would like to hear from ATC, especially any London ATC.

Thanks

[Gonzo]

In the UK the 757 is classified as a Medium, so on departure if you're also a medium we do not have to provide any wake vortex.

[1261]

Also true if you're in the UK's peculiar "small" category (E145, DH8C/D, F27/50, etc., etc.) - ATC is not obliged to provide any departure vortex wake spacing behind a 757.

[qsp888]

wait a minute, i was under the impression that a 757 is classified as heavy when in front, and a medium when behind!!!!!
i'm pretty sure this is widely used in the UK.

[tigtog]

Brownstar,

As above says we are actually required to provide NO vortex sep between M and S aircraft and 757's. The reduction to a minute, especially if referring to London, is due to our minimum dep. separation and thus we sometimes say "are you happy with a min behind a 757?" however this has nothing really to do with vortex.

However our procedures (Mats 1 for controllers reading this) state that :
"separation SHALL be increased at the request of a pilot"

This includes vortex wake to my understanding.

So if you want 2mins behind 757's ask BEFORE line up and we are usually quite happy but if you ask when already ON the runway this may not always be possible and the next a/c may have to go around.

Hope that helps.

[radar707]

Th eonly increase in vortex we apply with a 757 is on the final approach, if the following aircraft is a medium , then the vortex requirement is increased to 4 miles instead of the usual 3 miles.

On departure, unless you ask for 2 minutes then all you will be given is 1 minute (subject to normal separation requirements). The key to all of this is if you require 2 mins behind a departing 757 then TELL the controller, the gap might only work for a 1 min separation.

[West Coast]

Do most operators ask for the two minutes? Pucker factor is always high following one of those.

[1261]

Some do, some don't; I won't name names but the continental operators tend to be a bit more cautious than the Brits! Depends on the wind, etc..

[radar707]

A certain Spanish operator once told me after I'd given him 2 mins behind a 757 that he required 2 mins, I asked if he needed ANOTHER 2 mins as he already had 2 and he said company requires 3 mins behind a 757!!!

[j17]

radar 707

the simple reply is " vacate the runway " and join the queque if you have one.

[brownstar]

thanks for the ATC replies. Is there any source reference material that you could point me to as regarding the timing/spacing, the B757 preceeding and medium following. I believe that the 757 is classed sometimes as un upper medium? .
You might think it is strange that I am asking these questions but i am finding it difficult to 'pin down' in text.
A lot of the info that is available to aircrew is not specific on this or even contradicts the info that ATC has provided via PPrune.
I do believe the info that you have provided here, I wonder if there are any other aircrew that are confussed on this issue.
Are the spacing requirements different in other countries?

thanks.

[vector4fun]

Are the spacing requirements different in other countries?




In the U. S., we use two minutes or 4 miles...


============================================



FAA 7110.65

3-9-6. SAME RUNWAY SEPARATION



WAKE TURBULENCE APPLICATION



REFERENCE-
AC 90-23, Aircraft Wake Turbulence.

e. The minima in para 5-5-4, Minima, may be applied in lieu of the 2 minute requirement in subpara f. When para 5-5-4, Minima, are applied, ensure that the appropriate radar separation exists at or prior to the time an aircraft becomes airborne when taking off behind a heavy jet/B757.

NOTE-
The pilot may request additional separation; i.e., 2 minutes vs. 4 miles, but should make this request before taxiing on the runway.

f. Separate IFR/VFR aircraft taking off behind a heavy jet/B757 departure by 2 minutes, when departing:

NOTE-
Takeoff clearance to the following aircraft should not be issued until 2 minutes after the heavy jet/B757 begins takeoff roll.

1. The same runway. (See FIG 3-9-4.)


2. A parallel runway separated by less than 2,500 feet.

[Spitoon]

ICAO has a basic set of wake vortex spacings but many States have delevoped their own spacings based on experience.

The basic categorisation is based on aircraft weight but some in some cases an aircraft type that would normally be put in one category is deemed to fall into a 'higher' category because of the vortices that it creates.

So although there is a sort of standard, you'll find differences in many countries. The differences should be published in the relevant AIP.

[360BakTrak]

Go to a certain London airport and a 757 is classed as an 'Upper Medium' just to confuse the issue! :bored:

[Ausatco]

Down here a 757 is Heavy if leading, Medium if following.

Heavy heavies (>200,000kg) behind any other heavy - 90sec or 3 miles

Heavy behind a heavy - 2 min or 4 miles

Medium behind a heavy - 2 min or 5 miles

We use time or distance, whichever occurs first. Time is recorded to the nearest half minute, so you could record a two minute standard with aircraft only 90 sec apart. Ditto, 90 sec could be 60 sec in reality. There was a memo about 2 years ago talking about real 90 sec and real 120 sec, but it was never incorporated into MATS and is no longer in circulation, so is not applied.

Makes one wonder, that. I usually go for the distance standard - there's no argument with that.

AA

[Quokka]

MATS allows you to run two aircraft on a Sight & Follow a mile apart with the second aircraft quite happily riding the wake turbulence behind the first aircraft the whole way down....

:rolleyes:

[alexban]

I find it interesting that a 757 can be a heavy or a medium,depending on which country it is.Maybe in the future,due to trafic congestion,some smart guys will decide that all planes are medium to light.
As ,for me,I usually time 1'30 sec after the 757 lift off,then I start rolling,this will give~ 2 min between lift offs.:
I try not not make the day for atc,or for me and my passengers:ok: