Runway Separation - The Pucker Moment

[arctic radar]

To Tower ATCOs far and wide...

Regardless of the regulations of your country of practice, your skill, your bravado or your devotion to safe operation - there will come the moment whether it is your fault or otherwise, when you are faced with the hellishly scary 'piggy-back' scenario. i.e. a/c departing/climbing out (relatively) slowly versus an arriving aircraft going around and climbing like a Euro-Fighter in a hurry.

The means of resolving this has been discussed on this forum before and I don't intend to cover old ground. However, I would like to envoke a bit of discussion with Tower Atcos at busy airfields as to how their own regulations allow them to operate.

The PANS OPS 4444 regs of ICAO state as a basic standard for same runway ops that any arriving aircraft may only be cleared to land when there is a reasonable assurance that any preceeding departing aircraft will have crossed the end of the runway or started a turn. Importantly, there is no requirement for the departing aircraft to be airborne in order to issue landing clearance to the arrival.

As an ATCO who had formerly worked only in the UK, this was a bit of a surprise. The UK CAA work to the following standard:

CAP 493 Section 2 Chapter 1

15.2.2 Unless specific procedures have been approved by the CAA, a landing aircraft shall not be permitted to cross the beginning of the runway on its final approach until a preceding aircraft, departing from the same runway, is airborne.

Now the above standard actually avoids the issue of landing clearance. One could argue that an ATCO in the UK could clear an arriving aircraft to land whilst there is an aircaft which is still on the runway but on it's departure roll provided that the arrival does not cross the beginning of the runway until the preceding aircraft is airborne. However from my UK experience, most ATCOs interpret the above as meaning, 'Thou shalt not clear an aircraft to land until any preceeding departing aircraft is airborne.' (i.e. if the departure will not be airborne by the time the arriving aircraft will be over the threshold of the landing runway, the arrival will be instructed to go-around.)

I currently work outside of the UK and regularly observe ATCO colleagues issuing landing clearance to aircraft on long final when there are other aircraft occupying the same runway engaged in the take-off roll. The practice initially made me shudder as it was alien to me and didn't fit with my established strip movement practice amongst other things. But it seems to be a perfectly legitimate practice under ICAO.

However - and this is my main discussion point - I have regularly been involved with busy single runway ops in the UK with 'tight' situations between departing aircraft and arrivals. i.e. Departure airborne with just a glimpse of daylight under the wheels with the arrival inside 1 mile final. Now under UK CAA regs, this is permissable since the preceding departing aircraft is airborne and the arrival has not crossed the threshold of the landing runway (the pucker moment as suggested in the title). However, when a nice long runway is involved, the ICAO regulations are certainly not adhered to. ie. the fat, fuel laden departure would neither have turned nor crossed the end of the runway prior to the arrival crossing the threshold.

Is my interpretation of MATS part 1 wrong?
Is the less restrictive UK CAA stance unsafe?
Is the ICAO practice of 'anticipated aircraft movement unsafe?'

Discuss... if you can be bothered.

[NudgingSteel]

I've had a few beers and can spare you a couple of minutes....

I'd say your interpretation of MATS1 is correct, and unless somebody's MATS2 is specifically different, the departure gap is too tight with both overhead the runway at the same time.

I'd also venture to suggest that the CAA stance is more, not less, restrictive; witness the prescriptive "...shall not.." versus the much looser "...reasonable assurance..." stance of the ICAO bits. By not issuing a landing clearance until the runway is available, there is an element of separation on the runway built-in, particularly in the event of R/T failure (although you could then possibly argue that you're marginally increasing the risk of a g/a vs a departure).

I'd say the issue with 'anticipated' landing clearances is when a departure either fails to roll in time, or aborts t/o. Even if the visibility is good, consider the view from the flight deck of the arriving traffic, looking at the tail of an a/c halfway down the runway....for some reason there's no R/T input from either TWR or the departure (blocked freq / R/T failure somewhere etc): how easy is it for the arriving pilot to judge the position, speed and intention of the departure? Do they assume it's about to leap into the air at 150kt? What if it's braking during an RTO and coming to a stop at the midpoint?

In summary:
1) I'm more comfortable with the UK procedures...although will happily admit that's due to years of experience with them
2) can't remember second point due to beer

[HEATHROW DIRECTOR]

<<The PANS OPS 4444 regs of ICAO state as a basic standard for same runway ops that any arriving aircraft may only be cleared to land when there is a reasonable assurance that any preceeding departing aircraft will have crossed the end of the runway or started a turn. Importantly, there is no requirement for the departing aircraft to be airborne in order to issue landing clearance to the arrival.

As an ATCO who had formerly worked only in the UK, this was a bit of a surprise.>>

Do the "after the departing, cleared to land" procedures at some airports no longer exist?

I only had a couple of "formations" during my time at Heathrow, back in the days of runway resurfacing for weeks on end, but they were quickly sorted by placing them on headings.

[Gulfstreamaviator]

what happens with the last moment GA

Lets assume the departure is very slow to roll, and the landing captain initiates the GA. you now have the rolling aircraft just past V1, and the GA aircraft almost on top of him.
Now assume slightly less then optimum visability, add level 4 English.

Unless my landing clearance was LAND AFTER, it is MY Runway.

I am sorry, but as the lander would rather have the runway to myself, after all I have paid for it.
glf

[HEATHROW DIRECTOR]

<<Unless my landing clearance was LAND AFTER, it is MY Runway.>>

In the UK you shouldn't get the runway unless a landing is assured. How about in the USA where they clear everyone to land regardless of what's happening on the runway?

[General_Kirby]

"After departing cleared to land" is still in use, very much so. If your given this clearance then ATC is ensuring seperation against a list of set distances and criteria they must meet before issuing the clearance. In other words, if ATC are doing their job properly then you have nothing to worry about.
A land after, the onus is on you to continue and land another arrival possibly still to vacate at the far end.

In the scenario you describe hopefully ATC would have noticed the departure was slow to roll, and/or/both stopped the departure and sent you around with avoiding action/heading instructions if needed. I honestly cannot see any ATCO in the UK letting the situation develop to a point whereby you are going around a few hundred feet over the just rotating departure.

Also if its rubbish visibility and rubbish english from the pilots then ATC probably wouldn't be going for the tightest gap anyway, and if they do, rest assured they will (should) have a backup plan A and B if it all goes wrong.

[Heloboss]

.65 application

"Anticipated Separation" is our Mantra here in the US. The Controller is responsible to provide visual separation. I issue landing clearances to acft on final all day long and the departing acft has yet to taxi onto the rwy. I advise both of each other and in their acknowledgement (the pilot's) they are assuming some of the responsibility for separation. We have the 3000/4500/6000/RWY rule here depending on the type acft and that allows me to "control" rwy use and occupancy times with my timing of the clearances whether they are landing or taking off...(bearing in mind Wake Turbulence minimums too...)

I'm curious...what is the image of US FAA controllers to European or UK controllers....I used to work in the UK airspace environment at a couple of RAF bases, and never got a straight answer from the local boys (and lasses)...?

[Gulfstreamaviator]

General: but it did happen

At Luton, and the lined up aircraft "lost RT", and ATC was telling him to expedite his TO, we are getting closer and closer...and ATC gave us the GA, just as we came to the same conclusion.

As we received the GA call, the lined up aircraft acknowleged the expedite call, and made his rolling call. His call included all of the explanation of his problem, as he continued his verbalising take off roll......
We were now in the GA, at about 250 ft, (in a small biz jet), and going around, std GA......he was getting into the climb...
Our ROC was rocket assisted......ATC gave us a turn left to instruction.
I assume back up plan was to give me the GA, but foiled by the blocking of the ATC freq.

All resolved, but I still stand by my what if question.....

In an earlier life, GA training, we would make the GA with a little break right, then parallel, looking for the traffic. This was my immediate thought in this situation, solid VFR, so not a problem for me.

Heathrow Director: I hate being cleared to land when I am number 3....


glf

[loubylou]

The airfield the I currently work at withdrew the "after the departing xx, clear to land " procedure a while ago, so if it gets a bit tight, then send the landing aircraft around. Personally I would line up the aircraft in the gap then re-assess it before issuing take off clearance.
The bad news scenario of the departing aircraft being R/T fail after take off clearance is issued - then you would give a (possibly non standard ) go around with avoiding action and essential traffic information.

There is a difference though between that and a "land after the vacating xx" in that the first clearance is a landing clearance issued by the controller who has to make the judgement call that the departing aircraft will be far enough on the landing roll that the landing aircraft will be able to make a safe landing ( notwithstanding that the captain could go around anyway - but that is always the case )
This is a landing clearance as the phrase used is " after the departing xx cleared to land" - the procedure does not avoid issuing a landing clearance.

The second procedure is technically not a clearance - but the controller is giving the captain the option of landing after the vacating aircraft - and if goes wrong then it was down to the captain.
Except the Heathrow ( I think ) uses the phraseology " after the vacating xx cleared to land" which is a landing clearance.

Hope that's a bit of help!

louby

[timelapse]

The "after the departing" and "after the landing" procedures were scrapped at heathrow more than 6 months ago.. we now only have the "land after" as an option.

Rumours were that foreign crews especially found the whole thing too confusing.

[Desert Hunter]

Piggy Backs

then you would give a (possibly non standard ) go around with avoiding action and essential traffic information.

I'm interested in different Tower Atco opinions on how you should phrase this and whether you have any unit guidance. Obviously it's an unusual situation and rapid response is vital. With the prime objective being the avoidance of a mid-air collision, one could argue that you must say and do whatever is necessary and then worry about the fallout later. That's all very well, until of course you find yourself in that situation. The subsequent investigation determines that the situation - although unusual - ought to have been dealt with adhering to standard practice and your actions and/or choice of phraseology is called into question.

If you are unable or there is no time to co-ordinate with Approach, how should a Tower Atco resolve the situation?

[HEATHROW DIRECTOR]

Desert Hunter. Every eventuality cannot possibly be covered by the various MATS or by standard phraseology. In such circumstances the ATCO must use his experience and initiative to solve the problem to the best of his ability. It says in the UK MATS Part 1: "...nothing in this manual prevents controllers from using their own discretion and initiative in response to unusual circumstances, which may not be covered by the procedures herein."

In the situation you are concerned about, one solution might be: "Avoiding action, turn left/right......traffic is...." I've had a few of those and a heading change was the answer every time.

[chiglet]

I remember at Manchester, an Aviogenex TU134 being No 3 to two light a/c. Light no 1 landed long, to clear at R/w 28 Light no 2 landed "normally" to clear at Link "C" South
The TU134 was given at LEAST five "Overshoot" [G/A] instructions. Each one was acknowledged by "Roger"...He landed, just as No1 LA/c cleared the R/w.
He obviously was in control.......

[towerboy]

The common sense "approach" regardless of procedure is ONE clearance to use the runway at a time!
As soon as the departure is airborne, or a suitable distance along the runway..."cleared to land".
As soon as the arrival vacates the runway..."cleared...for T/O, to land".
This also provides structure to the thought processes, a logical sequence of events, and MAKES the ATC scan the important parts of the runway.
Watching an aircraft vacate on (especially) a rapid exit also allows you to identify possible conflicts with taxiing traffic.

Aircraft should report "ready" with their assigned position ie. "TWY A".
This would eliminate mis-identification of aircraft through (aircraft taxiing to the wrong holding point, ATC errors on strips, incorrect label application on ground radar, and therefore, ATC believing they are talking to aircraft 'A' when in fact they are talking to aircraft 'B'.

Clearing aircraft no.3 to land on 10 mile final gives no information to the flight crew on their position in the sequence, (let alone the departing aircraft that are going in the gaps).
Situational awareness is vital in this part of aviation, where aircraft get the closest, yet the procedures seem to be the most lax.

If there is an aircraft rolling out on the runway and you tell an other aircraft to "line up", the intersection should be included in this instruction, so that the aircraft rolling through know that the "offending" aircraft is behind them.

Conditional clearances should be used at all time where possible as 2 or 3 sets of eyes are better than 1.

Just the way I see it...

[cjlar]

In an airport very close to the USA we used to have a lot of A***f*t. We became very cautious when issuing a precautionary "In the event of a go around " as 3 to 4 times out of ten it was followed by a pause and "roger, commencing goaround" One learned!!