You said 'wake turbulence separation'. Check CAP 493 Part I 9.6.2 - there is no wake separation on departure between same weight types.
And as I said before - most heavies will go from the longer international runways, while the mediums will go from the domestic/European terminal. In this case, there is little need to mix aircraft types, and thus incur wake turbulence separation delays.
Yes, I did say 'wake turbulence separation'. Look back. That was in response to your comment that departures would have to be delayed for crossing inbound traffic. My comment was that, sometimes, departures are delayed anyway due to wake turbulence separation. LHR's traffic mix is about 30% Heavy. So if you restrict Heavies to the long runways in your plan, and all Mediums to the small runways, then you'll either have realtively low demand for departures off the two long runways, in which case there is no delay due crossing traffic, or you'll have Mediums in the mix there as well, in which case you'll have WTS gaps to get the inbounds across.
And Geffen, you are looking at CAP 493 Part I 8.6, which has nothing to do with wake. Since I had the tracks diverging at 5nm, the following aircraft could be released in approx 1.6 mins. But with the new, revised departure tracks on the new map diverging at 1nm, they can now depart with very little separation - 30 seconds or so.
You know most Heavies take 45-50 seconds to get airborne? With 30 seconds separation then you'll be clearing an aircraft for take off with the one ahead still on the runway.
Route separation on departure (assuming same wake category) applies as follows at LHR. 1 min: Routes diverge by 45 degrees or more
Route separation on departure (assuming same wake category) applies as follows at LHR. 1 min: Routes diverge by 45 degrees or more
AN-Conf/11-IP/3 3.2.1 Manual on Simultaneous Operations:
Independent IFR departures may be conducted from parallel runways provided:
b) the departure tracks diverge by at least 15 degrees immediately after take-off.
c) suitable surveillance radar capable of identification of the aircraft within 2 km from the end of the runway is available.
http://www.icao.int/icao/en/anb/meet...003_app_en.pdf
You missunderstand me. I am talking about
departures from the same runway, not parallels! If the routes of successive departures
from the same runway do not diverge 45 degrees then
you must leave 2 minutes between them. From the same runway.
There is a hell of a lot wrong with that.
I am at 300ft and fast approaching a point where I will have 1.25 seconds to make a land/go-around decision, and the last thing any captain wants is the aircraft swaying all over the place on an unstable ILS (Sensitive Area still compromised) and ATC wittering on about landing clearances and winds.
I have never had a CAT III landing clearance inside 4-5 miles, and I would consider it wholly unacceptable and highly irresponsible to do so.
Then I suggest you should never fly into a capacity constrained airport in CATIII. To give you a landing clearance at 4nm, then we'd have to apply spacing of 8-9nm between lanbdings, not 6nm, in CATIII. LHR's CATIII capacity would go down even more.
From FLIGHT INTERNATIONAL, 18-24 July, 1990
BA REPORT REVEALS LHR 747 OVERSHOOT FROM 75ft.
And I'm sure you are aware of all the mitigations in place to ensure that doesn't happen again.....