You are correct mate regarding being ex-UK. And the grey matter pertaining to some of the policies of my previous employer are a little on the hazy side.

Here in Canada, the Wake Turbulence standards are in black and white in the CARs. The reason I say black and white, in this now wonderful lawyer filled world we now live, I would hate to be standing next to someone in a court of law who had a nasty due to wake turbulence and you have no defence if you didn't have the standard.

To me, asking a pilot "are you happy to continue" means you're not.........why would that be?

Bekolblockage, I've been having a bit of a hunt around UK docs, and am a bit of a loss regarding your "NATS policy". Has there been a change sine AIC 17/1999 (that's the one I remember)?

I agree with you on that Jerricho.
Not sure how "official" the policy is at Heathrow, but from this:
http://wwwe.onecert.fr/projets/WakeN...ul_Johnson.pdf
comes this:
"•Wake Vortex Separation applied to 4DME from
touchdown.
•When the lead aircraft is inside 4DME and a reduction
of ½ mile or more in the required wake vortex separation
occurs, the pilot of the following aircraft must be
informed."
... meaning no need to say or do anything down to 1/2 mile below the standard?
Not saying I agree with it, just seems there's some fairly liberal interpretations of Doc 4444 out there.
Also seems to me the last 4NM is when you DO need it, as the chance of a recovery from a major upset at low altitude/low control effectiveness is fairly unlikely.

AsA wakes
 

Just for the record in dunnunder:

L following M 5nm (except light medium then nil)
M following H 5nm
L following H 6nm

A380 lots - hopefully under review
special standards for 757 (meduim when following, heavy when leading)

Bust any of these standards and you are stood down pending investigation.

Interesting how different they all are! I thought we were pretty well ICAO standard...

Blue:hmm:

bluerider777
Thanks for that. Our sep standards are the same here as Oz, including H-H 4NM.
I recall the change in attitude to WT in Melbourne in the mid 90's when it went from "do your best to get it" to " its non-negotiable". I remember several instances when the Tower started sending people around if a/c were handed off without the required WT sep, much to the chagrin of the APP controller.
It all seems logical of course, but its interesting to see how busy airports have interpreted the rules on a "needs must" basis. I'm sure Heathrow's capacity would fall way short of demand if controllers had to start applying a buffer.
Any other places out there that allow some "infringement" of the sep standards?
P.S. Out of around 900 movements a day here, more than 600 are Heavy. Light = zero!

The 'grey area' is due to the differing speeds that aircraft fly after 4DME. We cannot legislate for that, so cannot guarantee separation.

Just playing Devil's Advocate Gonzo.
Presumably you guarantee radar separation in IMC even though there is compression inside 4NM, so what is the difference?

Heathrow have a version on the UK system,with slight differences from what we use up north within Nats.For example Light following a Heavy in the UK Mats part1 is 8 miles.At LL it's 7.Light following a lower medium would be 6miles.At LL it's 5.
I suppose they could argue that they are very busy,and it's as near to ICAO standard that they can lose a mile.If I put a light 5miles behind a lower medium,it could well cause problems.LL it's OK.
With helis such as the AS332 (Small) and say a Saab 340 behind(Light) the requirement is 4 miles.With the speed differential,especially if the heli want 80kts inside 4 miles,then we always go for the buffer.Aim is to get 4miles when the heli is at touchdown.We don't have the 1/2 mile below standard at all.

You can guarantee the separation Gonze me old buddy.......unfortunately it means having your wake turb at 4 miles requires MORE further out. Bye bye landing rate.