Maintaining Seperation.

[NacelleStrake]

How do adjacent ATC sector's co-ordinate height separation of their A/C? say for instance, we are at level FL380 and enter the next sector, what if there is another A/C 'leaving' their sector at the same altitude, on the same airway? When, and how, does each sector get the 'head's up.?'

[HEATHROW DIRECTOR]

Information about flights is provided well in advance to all sectors which will control the aircraft so controllers will be anticipating traffic. Also, radar provides information to controllers and all sectors can see what is happening. If the aircraft is following its flight plan the handover to the next sector will often be "silent", i.e. no telephone or other contact will take place between the controllers and controler A will simply tell the pilot to change frequency to Sector B, which will be expecting the aircraft. Opposite directioo aircraft may be assigned different cruising levels but this may vary depending on traffic. A great deal of liaison either by telephone or by direct contact, when contrololers of adjacent sectors maybe sitting close to each other, also takes place.

[ZOOKER]

All en-route traffic within controlled airspace generally flies under the semi-circular flight-level allocation system.
Eastbound flights use odd levels, (e.g. 150, 170, 190), while west bounds use evens, 140, 160, 180, etc. Simple, but it works.
As HD says, if controllers wish to use opposite direction or non-standard levels, co-ordination must take place beforehand.
Flying across the North Atlantic, as the traffic flow is generally one-way, all levels are usually available to cope with the demand.

[NacelleStrake]

Thanx for the replies. Appreciated. I was watching a 'convergence' of A/C, [@ 90 degrees and FL360], on Flightradar24, and the thought did occur to me just how close do you have to be before 'separation' became an issue. Just happened, in this case, that the Tommy Cook started his descent, into LGW, from 360, whereas the Transavia maintained 360.......

[HEATHROW DIRECTOR]

Basic radar separation is 5nm, but this can vary depending on airspace. Closer to the ground it can be reduced to 3nm or even 2.5nm, depending on a number of factors.

[NacelleStrake]

Noticed today on Flightradar24 the BAW 268 Super Jumbo, from LAX, holding around NIGIT and then OCK. A VIR A340 entered the first hold sometime after the A380 but came out first! [It was 1000ft above the A380]. It was subsequently vectored for the LHR approach ahead of the A380. Why would the VIR be given priority over the BAW A380?

Heathrow Director, it always amuses me that when two converging A/C are at say, FL33025 and the other at 33975, this '50ft' soon disappears back to the std 1000ft mark.....:)

[HEATHROW DIRECTOR]

I have no idea why the Virgin flight should have beaten the Speedbird; there are many possible reasons, not all of them to do with ATC. E.g Sometime ago some BA flights would ask to hold because no stand was ready for them!

As for the altitude variations, I presume that FR has something to do with it. ATC displays usually provide the three digits for altitude and 50 ft is neither here nor there.

[DaveReidUK]

As for the altitude variations, I presume that FR has something to do with it. ATC displays usually provide the three digits for altitude and 50 ft is neither here nor there.FR24 will simply display the altitude that contributors' Mode S receivers are picking up.

For almost all commercial jet transports nowadays, that is sent to the nearest 25'. For an aircraft in the cruise, or level in the hold come to that, it's very common to see periodic variations of plus or minus 25 feet. I very much doubt that the presence or proximity of another aircraft has any bearing on these variations.

[Crazy Voyager]

I will hazard a guess and say either fuel pan or medical pan could have put him first.