divinehover

Hi All

I would like to get a programme off the ground to reduce runway occupancy time at our major hub.

Gatwick (or any other if relevant) is considered the world standard when it come to single runway operations and therefore runway occupancy.

I would like to know what, if any, procedures do the pilots and ATC's use in and out of Gatwick (or elsewhere) to achieve the efficiencies they see. It would be nice to read through a pilot/ATC briefing doc if available.

Many thanks

DH

737Jock

Line up when ATC tells you and be ready, vacate runway at highspeed turnoff at highspeed, don't panic when you haven't had a landing clearance by 200ft RA. Don't panic when they line you up with traffic at 3-2Nm on final.
Don't block tower frequency: checkin on arrival is callsign only, checkin for departure is non-existent (monitor tower frequency!!!).
B757 is considered a medium aircraft for wake-turbulence in LGW. I think they also can use 2.5NM spacing on final, mostly gaps are bigger to alternate depatures and arrivals.
And obviously fly ATC assigned speeds.

Also ATC have the ability to give conditional landing clearance, when crew on final call visual with departing traffic.

BOAC

divine - I was involved with all the major users airlines with the initial look at RETILS etc at LGW. There was a working group on reduced times and ATC will probably be able to put you in touch with someone.

Uplinker

Have the landing pilot also taxi the aircraft off.

The company I work for insists on left seat only taxying, so when right seat lands, there has to be a change-over during the deceleration and braking phase. This makes it difficult when right seat is landing because neither right nor left seat can judge the deceleration and dynamics of the moment sufficiently to decide whether the approaching exit is going to be achievable or not. If the same person is landing and taxying off, they will include the turn-off in their roll out deceleration assessments and sub-conscious calculations.

Bring back thrust reversers! Owing to the ridiculous fuel saving "initiatives", we don't use thrust reversers any more, and are reluctant to overheat the brakes too because it may impinge on our turn-around times. Therefore we are more likely to roll past to the next exit. Ditto flap 3 landings which result in longer roll-outs. Put an extra £1 on every pax ticket and use the fuel the aircraft are designed to use !!


(Sorry - bit of a rant, but my suggestions are genuine.)



U

Ian W

Wake turbulence categories are based on worst case wake with worst case stability of the wake vortex so are extended to extreme periods for 'safety'. Have the airport(s) invest in a LIDAR system that will monitor actual wake turbulence such as WindTracer by LM. (I am not related to the company but have seen it work)
Lockheed Martin · WindTracer® for Airports

In a day with a crosswind of 10 kts the wake from a previous aircraft will normall be clear within 30 seconds - why waste another 90 seconds of runway acceptance rate for a wake that is no longer there?

For safety a LIDAR system would be able to show the actual wake and significantly improve the acceptance rates on single mode runways and on multimode with a stream of takeoffs.

FlightPathOBN

Ian,

LIDAR:

There are no working wake systems that use LIDAR. There are a few in development, but none are currently working. LIDAR has very little use in the real world, as it cannot work when the air is too clear, or too many particulates, too dry, fog, rain, snow, etc. Currently, in EUR, they are looking at adding Ku and X band radar to the system to get it to work, but that is just another few years and a few hundred million wasted.

The LIDAR algorithms are still in the infant stage or providing something, but between the scan rate and processing rate, you get a reading about every 20 aircraft...

While the FAA has been at SFO for years with measurements, and it is approved for crosswind parallel ops, I know that you will find very, very, very few times when there will be clearance for that operation to be used.

Crosswind:

Crosswind effect on wake studies have not been comprehensive enough to prove anything other than a guess if it will work. One significant item not accounted for was the effect of crosswind on the aircraft itself. If the aircraft starts to crab, or you have different flaps/brakes per wing, each wing will generate a different strength of vortex, and may even lose the couple and crow stablity. Lose the couple, and the vortex act independently, with the crosswind actually building (feeding) one of the vortex creating a stronger, longer lasting deathtrap. That potential has just been pointed out and realized as an issue, (and in fact, there has never been a model where the aircraft was in a crab or skewed configuration.

RECAT:

The FAA RECAT is actually not too bad, and with only 6 wake cats, was very easy for controllers to learn. It was pulled of quite well at KMEM.
The RECAT program at Memphis has some good success with FedEx during the night movement, but they have a good mix to work with, the normal ops at Memphis saw little benefit at Memphis. The FAA has some plans for implementation at other locations, but the FAA has no $$$.

ROT:
For the ROT, you will find very, very few airports with the high speed exits in the correct configuration or location. Most were designed with DC-9 parameters and are useless. While terminals have expanded, and runways improved, little has been done with exits.

Creating/optimizing the exits, in my opinion, creates the best bang for the buck. You can reduce wake and optimize the ARR queue, but if they cant get off the runway, there is little benefit.

Diverse DEP:

For DEP, the best short term solution is the diverse DEP, with turns as soon as possible. This way you can have a turn right, turn left, and straight config to get aircraft off the ground with little chance of wake encounter and little chance of running up on each other....

Fixing the RNAV DEP procedures with a few additional waypoints usually levels the field very well, and provides protection from a wake encounter...

DaveReidUK

We seem to have drifted (no pun intended) from runway occupancy to wake separation.

Returning to ROT, many airports where this is an issue (i.e. slot-constrained ones) are starting to look at real-time 24/7 ROT monitoring and analysis.

Raising and maintaining crew awareness of the need to (safely) minimise the time spent occupying a scarce runway resource is becoming increasingly important, and most airports have a Flight Ops Committee where such issues are discussed with operators.

Gone (well mostly) are those periodic exercises that many airports used to undertake with observers and stopwatches, measuring and recording a sample of ROTs, or by asking the ANSP to try to derive data on velocity and acceleration/deceleration on the runway from successive radar recording plots.

With the advent of multilateration and ADS-B, it's now feasible for an airport to profile every runway movement and to provide its operators with timely feedback on their crews' performance. I know that LHR, for example, were looking at such a system a couple of years ago, although for various reasons it hasn't yet materialised, but I don't think it will be long before we see some of the world's leading airports doing continuous ROT monitoring.

jumpseater

Well if you knew anything about the subject matter you'd realise you can't consider one without the other.

edit: For the OP Luton EGGW may be worth throwing in the mix too. They don't have a full length parallel taxiway at either end, when busy they have to be very adept at moving the traffic, and the flight crews have to be on the same page too.

Gonzo

We do record and analyse both landing occupancy and departing line-up times for every flight. Anything significant gets acted on pretty quickly nowadays.

To the OP, from the ATC point of view you need good use of conditional clearances (whether it be in a single runway mode or a segregated departure runway). Also a good appreciation of aircraft performance along with airport infrastructure. In a good headwind at LHR you could get a medium away in a 5nm arrival gap between two mediums for sure, possibly a heavy. However, sometimes I would struggle to get a medium departure away in a 6nm gap between two heavies early in the morning when those heavies have tired crew on board and everything takes a little bit longer, including vacating the runway. For a single runway operation, Gatwick has better positioned RETs for mediums, so the normal arrival gap for them between mediums is 5nm, I believe.

From a flight crew point of view, prompt line ups, which in the UK includes the ability, once in possession of a conditional line-up clearance, to cross the holding point before the one ahead is cleared for take off provided the following aircraft is departing from the same point (or behind).

Send me a PM and I'll see what we can find from LHR.

DaveReidUK

If that's a roundabout way of saying that whether you're a Heavy or a Medium will affect your ROT, then I'd have thought that was so obvious as to not need stating.

On the other hand if you're suggesting that what happens between crossing the threshold and vacating the runway (the start and end of AROT measurement) is somehow dependent on the wake category of the preceding or following landing aircraft, I'd be fascinated to know how that works.

FlightPathOBN

basically because the ADSB bandwidth is used up.

multi-lat is interesting, but in reality, again, bandwidth is used up already, even without adding more information to the broadcast. For the Multi-Lat, I dont think anyone wants to be adding more towers at this point.

as noted before, ADSB can handle about 4000 messages per second before it degrades. When we did the trials at Munich, there were upwards of 30 THOUSAND message per second already

There is a direction in using 980 MHZ ADSB for ground ops, and I believe there are a few of these systems in operation...

the 1090 Committees are stuck in limbo, and AIXM is looking at revising the packet content anyways...

In regards to ROT and Wake Cat, the Wake Cat has nothing to do with ARR ROT.
It may be a stretch to say that the Wake Cat has something to do with the DEP queue, and while not ROT, it is a way to optimize the queue and airport throughput on DEP.

jumpseater

I'd read Gonzo's post myself.

DaveReidUK

True, congestion on 1090MHz is a growing problem, with ATCRBS, Mode S, ELS/EHS, TCAS, and MLat all competing for the spectrum, though in this case it was organisational rather than technical issues that stalled the project.

The system BAA was looking at not only did automated AROT/DROT calculations, but would typically capture 50-100 or more data points during a landing rollout, allowing it to produce a deceleration profile (you could even deduce what autobrake setting was being used) and accurately measure exit speed. Obviously this made use of the fact that ADS-B sends velocity as a first-order parameter so you're not dependent on calculating groundspeed averaged over a succession of radar or MLat plots.

divinehover

Thanks for all the replies

I was thinking in the lines of simple, practical measures that can be taken by pilots and ATC's to improve the ROT. I think the first posts answers some of that.

Musket90

Airports like Gatwick, Heathrow and at peak times Stansted need both the right infrastructure and ATC procedures to minimise runway occupancy. These can include designing rapid exit turn-offs at the correct location and angle, providing RETILS at these turn-offs. It was proven through trials at Gatwick that RETILS reduced runway occupancy times.
The correct location and angle of RETs for arrivals is essential otherwise the runway is occupied longer than necessary. A 25 deg angle is considered best and for medium size types like A320/B737 a distance fo 1600-1900m from landing threshold is about right. For "heavies" the distance from threshold needs to be increased to about 2100m.
Also important is departure route after take-off which is often initially based on noise issues, so if an early left or right turn is possible with no vortex spacing or ATC airspace issues then an efficient departure flow is possible with consecutive departures turning left and right.
Another factor is general taxiway infrastructure and number of parking stands available. If the runway can cope with 40 arrivals an hour but there's limited taxiway infrastructure and few stands to cope with it then the movements have to be artificially capped so the limited infrastructure can cope. Same reason can apply for the number of passengers that can physically be processed safely through a Terminal building with customer service in mind.

DaveReidUK

Hence the 3 additional RETs planned for 09R at Heathrow, following abolition of the Cranford agreement, to increase the sustainable arrival rate and facilitate alternation on easterlies.

TAAMGuy

From the ATC side of things, I believe that ROT's are a cultural issue, as much as anything else. It requires an environment where the controllers are pushing as much as they can for efficiency. This crosses into the cockpit with effective communication, allowing flight crews to properly plan, and then manage their energy accordingly.

If the controller exudes a laiisez faire attitude, the crews will pick up on this and be a little more relaxed. If the controller is pushing with emphatic clearances, and phrases susch as "plan first available exit", "expedite to the next high speed", etc. then the flight crews will pick up on this and play ball.

I have seen procedures come and go, but to my mind the most effective tool is the collaboration between the controller and the pilot(s) to really perform for the benefit of all. It's a culture. Two cases in point come to my mind representing opposite ends of the spectrum. Years ago as a pax on a flight into KBOS, we landed in a A320 and the pilot hammered the reversers and the brakes to the point where I observed tire smoke just prior to the aircraft turning off into the exit. The other scenario involved a BA 747 crew wanting to taxi the full length of the runway, prior to departure, to inspect it for themselves after it was swept of snow and duly inspected/reported. Their request was denied.

I can tell you that here in Canada, ROT's are again coming up on management's radar as every last ounce of efficiency is being squeezed out of airport operations coast to coast.

DaveReidUK

Worth mentioning in this context Airbus's Brake to Vacate (BTV), available as an option on the A380 and standard fit on the A350: Brake to Vacate*| Airbus, a leading aircraft manufacturer

Though I was surprised to hear from NATS at a recent conference that at Heathrow only one of the four A380 operators at LHR uses it (no, I don't know which one).

EK380

BTV (Brake To Vacate) works well in reducing Runway Occupancy Time.

The one using it at LHR is EK (Emirates). LHR is presently collecting data on the use of BTV. Asking all EK 380's for the planned exit etc...

Gonzo

BTV is not a cure-all.

Many people just assume that it is there for, and will be used to, minimise ROT.

One could just as easily see a situation where it is used instead to roll to a further exit than normal for the same ROT as a non-BTV aircraft of the same type.