What are the rules for landing separation?

[dscartwright]

Hi all,

As a PPL who learned to fly at an airfield with a nice long runway I'm used to "Land After" clearances.

However, I was sat at a holding point at Gatwick as SLF the other week, just after the Captain had told us all: "Sorry, they've changed the runway on us, so we'll have to wait a bit".

Clearly this meant that a few flights would take off and a few would land on the "previous" runway while they cleared the pattern, and then we'd launch the opposite way.

So we sat there watching out of the window. And golly, there were some pretty slimline intervals between aircraft. The shortest I saw was about 15 seconds between the wheels of one aircraft leaving the runway and the wheels of the landing aircraft touching down.

I'm intrigued to know just what the minimum legal separation between departing and landing aircraft is. Clearly at a place like LGW, and in commercial flights, the concept of "land after" isn't a valid concept.

Cheers,

Dave

[Roadrunner Once]

Clearly at a place like LGW, and in commercial flights, the concept of "land after" isn't a valid concept.

Why not? :confused:

[timelapse]

It is a very valid concept. Probably used it 10 times today at Heathrow. But you can't use it following a departure :-)

[Geffen]

Am I right in thinking that at KK they still use 'after the departing cleared to land'?

[HEATHROW DIRECTOR]

Gefen... I'm curious too..

dscartwright.. There are (or were!) two procedures: "Land after", which you are used to, which puts the responsibility squarely on the pilot. There is another one: "After the landing xxx, cleared to land" (and, maybe still, "After the departing xxx cleared to land") which are safe ATC clearances which can only be used in certain conditions. Eg after a landing aircraft which is anticipated to have left the runway, or be at least a certain distance down the runway when the next one touches down... Oh yes, even with large commercial jets it is (or was!) legal to have two on the runway at the same time.

Hopefully a current controller (timelapse?) will put us right...

[Talkdownman]

See Paras 8.3 and 8.4 in GEN 3-3-3:

http://www.nats-uk.ead-it.com/aip/current/gen/EG_GEN_3_3_en.pdf

[Geffen]

Curious that the AIP still states the 'after the landing..'etc at Heathrow when they were withdrawn as a local procedure by management.

[HEATHROW DIRECTOR]

Geffen.. Very interesting. So at Heathrow there are no such procedures now? Presumably the spacing has been increased to account for this, but still you must get many more go-arounds?

[CommandB]

As a pilot who has been based out of STN and LTN, never have I heard the "land after" clearance. Normally if there is one to land/roll, we get "continue approach, expect late landing clearance" or "expect late landing clearance at XX miles" Usually get this other places too - DUB, BGY, GRO...etc.
Dublin are particularly prone to this ive found! Alot of the time right at the minimums call do we get our landing clearance! :}

[timelapse]

The "after the landing" and "after the departing" clearances were withdrawn from use at Heathrow (and I believe Gatwick) some months back after it was decided that they were too confusing for pilots. I can understand why really, despite how useful they were, most foreigners will struggle with even the "land after" and read it back as "cleared to land".

For that reason I only normally try to use it with British airlines and then only when I really, really have to with foreigners.

[hangten]

Now here's something which has been the topic of hot debate recently at units...

First of all, taking an arrival following a departure:

Gatwick and Stansted can still use the 'after the departing cleared to land' procedure after a comprehensive safety case was put forward for it's use in high intensity single runway operations.

The separations for this procedure are as follows:

Once the landing aircraft passes above the landing threshold ('the keys') the departing aircraft will either be airborne and 2000m along the runway, or not airborne and 2500m along the runway. This in theory allows a departing aircraft to still be on the runway when an arrival touches down - but taking Gatwick's runway as an example the displaced threshold and overall length renders this virtually impossible. Certainly 10-15 seconds is perfectly reasonable and easily achieved whilst meeting these requirements.

Heathrow and Manchester both withdrew this procedure.

To issue a standard landing clearance MATS 1 procedures state that an aircraft should be issued with a landing clearance before it is overhead the runway. After much discussion, including SRG, the runway is confirmed as the departure and the landing runway and hence in this case it is not the landing threshold but the start of the starter strip that the aircraft should receive it's clearance before. In this case, it's still perfectly possible to have approximately 15 secs between a departure rotating and an arrival touching down, but less likely.

For an arrival following an arrival:

All airports can still use the standard MATS 1 'land after' procedure, for which there is no standard separation to my knowledge. This procedure essentially puts the requirement for separation in the hands of the pilots, indicated by the ominous omission of the word 'clear' in any tense. In this case, if all parties are happy then there may well be two landing aircraft touching the runway at the same time - albeit virtually at the opposite ends. This 'concept' is just as valid at major airports as at a local airfield. Of course, controllers and pilots use their skill and judgement to decide what is reasonable, and the distances involved are vastly increased to take the speed, weight and manoeuvreability of the aircraft into account.

Also at Gatwick and Stansted there is the opportunity to issue a 'after the landing/landed/vacating cleared to land' which works in a similar way to the other clearances above. In this situation the controller is ensuring that the first arrival will have vacated the runway by the time the second crosses overhead the landing threshold.

I'm not sure if Heathrow and Manchester can still do this, but presumably they can.

Phew. If you're still here and not an ATCO or pilot, well done, you really are an enthusiast...

To sum up:

A 'land after' following another arrival is prefectly acceptable at all airports and is issued at Heathrow and Gatwick quite frequently. I'm surprised that Luton and Stansted use this less.

If you receive a 'late landing clearance' at whatever distance, against a departure or arrival ahead, this should be received before your aircraft is overhead the physical concrete/asphalt of the runway.

At Gatwick and Stansted you may also receive an 'after the departing cleared to land' clearance which ensures the specified separation given above.

[timelapse]

"After the landing cleared to land" was removed from Heathrow as well FYI.

[jimtherev]

Now here's something which has been the topic of hot debate recently at units...

First of all, taking an arrival following a departure:

...
The separations for this procedure are as follows:

Once the landing aircraft passes above the landing threshold ('the keys') the departing aircraft will either be airborne and 2000m along the runway, or not airborne and 2500m along the runway. This in theory allows a departing aircraft to still be on the runway when an arrival touches down - but taking Gatwick's runway as an example the displaced threshold and overall length renders this virtually impossible. Certainly 10-15 seconds is perfectly reasonable and easily achieved whilst meeting these requirements...



Sucked me teeth at this one: suppose the departing a/c suffers a rejected takeoff? Does the procedure above allow enough time for a TOGA?

[choclit runway]

The procedure is simply used to buy a bit of r/t and/or thinking time for the controller; not to reduce the distance/time between runway movements. At busy single runway airports it is not uncommon to issue a late landing clearance with far less than the stated distances here.

[terrain safe]

Also at Gatwick and Stansted there is the opportunity to issue a 'after the landing/landed/vacating cleared to land' which works in a similar way to the other clearances above. In this situation the controller is ensuring that the first arrival will have vacated the runway by the time the second crosses overhead the landing threshold.


Not at Stansted I'm afraid, and never used either. After the departing yes though.

[hangten]

Does the procedure above allow enough time for a TOGA?

Yes, absolutely. It's my understanding that flight crew will initiate a go around up to two seconds after touching down, at this stage if an aircraft which is 2500m along the runway is just calling aborting then there is a bigger problem...

[chevvron]

'Land After' is really akin to saying 'land at your discretion' but hang on a sec, that's FISO phraseology, and FISO's aren't allowed to say 'runway occupied, land at your discretion' dohh!

[criss]

And anyway, 15 secs is a loooong time...

[Roffa]

Yes, absolutely. It's my understanding that flight crew will initiate a go around up to two seconds after touching down, at this stage if an aircraft which is 2500m along the runway is just calling aborting then there is a bigger problem...

I would've thought anything that was still barreling along on the ground after 2500m would be well past V1 and ain't stopping in whatever is left of the runway.

[hangten]

That's my point exactly. :ok:

[NudgingSteel]

If the lander is doing 130kts then 15 seconds is just over half a nautical mile. Tightish but not that unusual at a busy airport - for the lander it'd be a later landing clearance than they'd like but on the other hand, larger spacing on final means longer delays in the hold (or extended vectoring or earlier speed reduction), plus a reduced departure rate, all of which costs money and time for the airlines. It's a fairly fine balance.
The absolute, overriding priority is safety and specifically having a plan in case it does all go pear-shaped. As long as a go-around can safely be turned away from a departure it's alright. When you're boxed in by weather or other traffic, though, with limited options, that's a different matter.

[loubylou]

As an aside - "land after the vacating xxx rwy xx" is not the same as " after the landing xxx , cleared to land rwy xx"
The first means that the pilot lands on his own judgement, and is not a landing CLEARANCE - however a controller won't issue the clearance unless he deems it to be safe, the second IS a clearance.
The semantics are that in the first case , if it all goes wrong then it was down to the pilot, the second, the controller.
However, obviously the pilot still elects to land or not whether given a straight landing clearance or one of the above.

louby

[2 sheds]

"land after the vacating xxx rwy xx"

Speaking of semantics, should that not be "(Runway...,) land after the..." ? When did "vacating" creep in?

2 s