Gatwick Approach questions

[FlightPathOBN]

I have been hearing quite a bit about the approach separation at Gatwick. It appears that there are 2 hold patterns, light/medium and heavy, and aircraft are queued in accordingly with a 4nm separation, then tactical, (by that I mean the different aircraft approach speeds can lessen or extend the 4nm separation.)

Is this an accurate description of how Gatwick ATC does this?

From a pilots perspective...how does this work for you operationally?...it would appear that according to wake turbulence standards, this close of a following distance would cause issues, I just havent really heard of any....

thanks for any and all responses...:ok:

[HEATHROW DIRECTOR]

I'm sure one of my Gatwick ex-colleagues will respond, but a few basics which apply anywhere..

Holding patterns are not (usually) designated for particular types of aircraft so the patterns used by Gatwick will be used for anything from a light biz jet to the biggest airliner.

Separation on final approach depends on many factors, weather, day or night, other traffic, etc. The exact spacing is determined by ATC and achieved by instructing pilots to fly at particular speeds which they are required to maintain as accurately as possible. 4nm maybe a basic separation, but this will be extended, possibly up to 10nm, for wake turbulence reasons or to accommodate departures from the same runway. Aircraft are divided into weight categories for wake turbulence purposes and those categories determine the spacing to be achieved by ATC.

HTH

[FlightPathOBN]

HTH,

Thanks for the reply...I am hearing this same 'story' on Gatwick from several regulatory sources, and it seems a bit unusual, but as I have heard this from several sources, I really want to sort it out. Much of what I am being told appears far out of normal practice and ATC procedure.

The 2 hold patterns for light/medium and heavies, would appear on the broad brush to be plausible, but logistically, drawing a single queue from 2 multi-variant sources would be difficult.

The issue with the 4nm separation, as this is far below ICAO standards on some combinations, was very concerning, and wake turbulence is a reality...

I have noted that when the aircraft come in faster, with flaps 20, wake turbulence is far less that flaps 30 or 40, so that could account for a tighter spacing with fewer issues, again, I am trying to rationalize the situation.

Gatwick does bring alot of aircraft in...so many agencies are looking at their model.

Thank you for the reply...hopefully

[30W]

As a pilot, although not Gatwick based, I can assure you KK (LGW) is a very, slick, efficient and professional service.

KK as we know is a multi-mode runway, ie. has arrivals and departures. Arrivals are therefore 'Gapped' or 'Packed' as required by KK Director (based in TC at Swanwick), according to the requirements of KK Tower. If there are departures, then 'Gapping' takes place, and arrivals are normally spaced at 5nm down the final approach, wake vortex requirements permitting, to allow a 'departure' in the 'arrival' gap.

If there are no departures (rare), then traffic can be 'Packed' and will be sequenced at 3nm on final approach as there isn't the need for a departure between the arrivals.

KK has only two 'stacks', both south of the field due to it's proximity to LL (LHR), and the flow of traffic that routes through the 'KK/KK gap'. Sequencing is very similar to that of the two southern holds of LL, ie. integrating traffic into a single flow from 2 holds towards the final approach. The difference is that LL then through the FIN (Final) Director integrates two streams, north and south, into one final approach sequence. KK has only the southern stream sequencing onto finals.

From a pilots perspective, the system is highly efficient, highly effective, and also, when capacity allows, highly flexible. Despite the high traffic density at times, it is an extremely comfortable place to operate through, because of the high quality of staff validated for this unit.

A star + on all occasions, and look forward to buying the 'starbucks' on my next regular visit:ok:

30W

[30W]

Flightpath,

You had added a message whilst I composed my last, so sorry for another response!

Not sure either where you are located, or indeed what the motivation is behind your query of UK wake vortex seperation standards?

A little history however - the UK has it's own wake vortex categories above and beyond ICAO standards. The UK, splits ICAO's Medium into Upper and Lower Medium. Also, certain UK airports such as LL can use 'reduced wake vortex seperation minima. This allows 2.5nm seperation rather than 3nm under certain conditions.

I know and understand that this can initially seem highly emotive, but let me try to assure you this wasn't done either lightly, or without appropriate data collection exercises. When the UK first moved this direction, many years ago, there was much raising of eyebrows (mine included!). The trial that resulted in the system we use today however showed NO increase of wake vortex incidents, minute increase of go-around incidents due to insufficient spacing, and therefore no safety reduction. Reduced seperation standards (below ICAO) therefore exist at certain airfields in the UK, under stringent rules, and constant monitoring.

I'm a pilot, the UK system works, it's safe, it's efficient. It's all of these because of the skill and professionalism of the NATS staff at the units concerned. Can it be made to work elsewhere? Of course it can, but stringent standards of who is validated to work these conditions has to exist, else the consistent high standards of controlling (and I DO mean high), erode the very small margins that exist.

Again, not sure of the intent behind your query, but all I can say, is as a humble pilot, it works EXTEMELY well and EXTREMELY safely here.

30W

[HEATHROW DIRECTOR]

<<The 2 hold patterns for light/medium and heavies, would appear on the broad brush to be plausible, but logistically, drawing a single queue from 2 multi-variant sources would be difficult.>>

I don't fully understand what you mean but be advised that a vast number of airports around the world have similar procedures. At Heathrow there are 4 stacks, all of which are used for a multitude of aircraft types. There is no difficulty at all in producing a single approach sequence from "multi-variant" sources.

[Spitoon]

Reduced seperation standards (below ICAO) therefore exist at certain airfields in the UK, under stringent rules, and constant monitoring.There's nothing non-standard about 2.5 mile spacing - it's in the ICAO books and applicable under certain circumstances.

[30W]

There's nothing non-standard about 2.5 mile spacing - it's in the ICAO books and applicable under certain circumstances.

I gracefully stand corrected:O, in the days when I was involved with the UK approval process it wasn't. It was however some years ago now! (grey hairs very much evident!):eek:

[HEATHROW DIRECTOR]

30W... know the feeling; I'm scared to say anything on here nowadays.

[FlightPathOBN]

Thanks for all of the replies..rest assured, I understand the system works great for everyone, I am just trying to understand what I have been told about why.

There is no difficulty at all in producing a single approach sequence from "multi-variant" sources.

Understood, I am familiar with multi-variant stacks...my query was based on having separate hold patterns with heavies in one, and light/mediums in another, and how that would blend. From what everyone is stating, it appears that the hold patterns at KK are not segregated by weights.

As a pilot, although not Gatwick based, I can assure you KK (LGW) is a very, slick, efficient and professional service.

Concur..with all respect for the system and the people behind making it work.

Not sure either where you are located, or indeed what the motivation is behind your query of UK wake vortex seperation standards?

In the light of PBN/RNP, with the potential for the ac to be on the same horizontal and vertical profiles, so there is alot of criteria and regulatory discussions about separation spacing.
As an example, currently, heavies keep low on the GP, and others go a little high when following, and while this is not necessarily formulated in regulations, it is practical in operations.

Everyone, my query is much more in understanding how the exemplary operations at Gatwick work, from people in the system, rather than from a regulators perspective.

(for reference, I am based in the PacNW...)

[FlightPathOBN]

A little history however - the UK has it's own wake vortex categories above and beyond ICAO standards. The UK, splits ICAO's Medium into Upper and Lower Medium. Also, certain UK airports such as LL can use 'reduced wake vortex seperation minima. This allows 2.5nm seperation rather than 3nm under certain conditions.


this document references all of the UK weight cats and wake sep distances as my other reference...
http://www.skybrary.aero/bookshelf/books/1166.pdf

[Gonzo]

Heathrow generally runs a standard 3nm final approach spacing regime.

Heathrow Approach have a 2.5nm final approach separation minima.

If conditions are suitable, then the Tower and Approach can agree to move 2.5nm spacing.

All of the above applies to non-vortex pairs.

[30W]

Flightpath,

I'm not sure where different holds exist for different wake catergories - i've been very fortunate, I've operated around the globe but never come across it happening either operationally or regulatory. Is there somewhere it does exist that you have been looking at?

There are NO UK stacks that exist for for specific wake vortex categories. If there are I'm now going to be liable for significant cost in curries and beer:uhoh:

With regards to flying of the G/S. Various 'old wives tales' exist in relation to this. I can only offer you my experience. NO ONE deliberately flies beneath the G/S once established - heavies or otherwise.

Neither does intentioanlly flying high on a G/S take place for several reasons:-

1. Ones doesn't always know the wake votex category of the aircraft ahead. One might guess, but doesn't necessarily know unless visual etc (IMC?).

2. Most intermediate approaches these days are flown with the autopilot engaged. It's accurate, it's efficient, it provides minimum flight deck workload which in turn produces other monitoring/management benefits. There's not an autoplilot in the world that can say fly 'one dot high' down the G/S. If we all flew slightly above the profile of the preceding aircraft, for 'possible' vortex reasons, we would very rapidly all be on 'ex shuttle' arrival profiles (no, not BA type shuttles:rolleyes:).

I'm sure you'll get far more professional and qualified responses than my own, especially from UK validated ATCO's, but from a pilots perspective, I really don't have a problem, and struggle to understand the environment one wishes to create where suddenly it may exist. The LTMA is of course one of the most densely 'traffic' populated areas that exists....

Brgds
30W

[Roffa]

Gatwick tower advise Gatwick approach what spacing they want.

If there's departing traffic a gap will generally be between 5nm and 6nm for one departure to get away in. Depends on the wind.

If no departures then the minimum separation of 2.5nm can be used when appropriate. Otherwise likely minimum spacing will be 3nm.

The separation on final between two aircraft will never be less than the required minimum wake turbulence separation.

Standard speeds are used.

Continuous descent (low power/low drag) approaches are aimed for by ATC providing track miles when giving descent.

It's the direction you are arriving from that dictates the hold you use, not the aircraft type. The latter would be impossible, or at least vastly and unnecessarily over complicate the airspace for no point that I can see.

[FlightPathOBN]

from a pilots perspective, I really don't have a problem, and struggle to understand the environment one wishes to create where suddenly it may exist.

Concur...as everyone is aware, EuroControl is looking at a recat of the separation minima, this is also coupled with SESAR projects to automate ATM, and put the AT Controller in an oversight mode rather than direct hands on...
I know, I know...and I dont look for anything viable in these regards for quite some time, and by then, who knows what avionics will be like.

So this isnt about creating a problem, (well, perhaps creating a different problem ..ie like the unintended consequences of RNP), its about updating and using as a foundation, a system that really works, hence many of my foundation questions in ops....

Please keep the comments coming...:ok:

[FlightPathOBN]

30W,

Thanks for the reply.
With regards to flying of the G/S. Various 'old wives tales' exist in relation to this. I can only offer you my experience. NO ONE deliberately flies beneath the G/S once established - heavies or otherwise.
Neither does intentioanlly flying high on a G/S take place for several reasons:-
1. Ones doesn't always know the wake votex category of the aircraft ahead. One might guess, but doesn't necessarily know unless visual etc (IMC?).

In the US, FAA AC 90-23F Aircraft wake turbulence, notes the following;

"a. When landing behind a larger aircraft, stay at or above the larger aircraft's final approach flight path.

b. Pilots of all aircraft should visualize the location of the vortex trail behind a larger aircraft and use proper avoidance procedures to achieve safe operations. It is equally important that pilots of larger aircraft plan or adjust their flight paths, whenever possible, to minimize vortex exposure to other aircraft.


12. Pilot responsibility
c. For operations conducted behind heavy aircraft, ATC will specify the word 'heavy' when this information is known. Pilots of heavy aircraft should always use the word heavy in radio communications.

(1) pilots of lighter aircraft should fly on or above the glidepath. Glidepath reference may be furnished by ILS, by a visual slope system, by other ground based approach slope guidance systems, or by other means"


While this is an AC, it does have some foundation. In RNP, as the procedures do not have to be coincident, a 2.8 GPA is frequently used for heavy aircraft.

[Roffa]

FPOBN,

You are starting to mix procedures/questions from across continents and across regulatory regimes, a recipe for confusion.

FAA ATC operates slightly differently and offers more in the way of visual approaches and the handover of separation from ground to cockpit. I'm not 100% sure, but I would expect that that is more what...

In the US, FAA AC 90-23F Aircraft wake turbulence, notes the following;

"a. When landing behind a larger aircraft, stay at or above the larger aircraft's final approach flight path.

b. Pilots of all aircraft should visualize the location of the vortex trail behind a larger aircraft and use proper avoidance procedures to achieve safe operations. It is equally important that pilots of larger aircraft plan or adjust their flight paths, whenever possible, to minimize vortex exposure to other aircraft.

... is aimed at.

Certainly it would be difficult for the pilot to do any of that when in IMC on the approach all the way till touchdown. UK ATC does not state 'heavy' in r/t transmissions.

In your quest for knowledge please don't muddle things up. In a thread that is supposedly about Gatwick, quoting FAA stuff is irrelevant. What is it exactly you want to know? The original questions have, as far as I can read, been answered. If there's something else, please state clearly.

[FlightPathOBN]

Roffa,

Understood..

Remember that I was saying that many different regulatory agencies are looking at the Gatwick model?
The FAA AC, may or may not have an equivalent ICAO, CAA, or whatever reference..I just dont know,
and while the Gatwick model works very well, there is certainly alot of regulatory substantiation behind it....

I am trying to wade through the regs, criteria, regulatory guidance, and what is circulated on a high level, as we all know, there is frequently a difference between the criteria, regulations, and actual operations.

As an example, according to the FAA heirachy, NextGen is in operating beautifully...and worth every penny of the $4 Billion dollars spent so far.

[twentypoint4]

Another reason why the Gatwick operation runs so smoothly (apart from the great controllers ofcourse ;) ) is because they are afforded the luxury of having a relatively large chunk of airspace to play with. Being the southern-most airport in the london TMA enables them to be really flexible with the inbound stream down to the south of the field.
It also helps that KK's runway is kindly alligned with EGLL's for more-straightforward airspace and procedure design. Stansted, another London single runway airport, have a bit more of a hard time mainly because their runway is a sw/ne orientation causing the design of airspace and procedures to be very awkward alongside the other London airports.
I also can confirm that Gatwick's (and every other London airport's) holds are each filled with aircraft depending on the inbound route rather than the weight.

[30W]

FlightPath,

I agree the FAA mandate the use of 'Heavy', and that it has it's uses from an awareness point of view. Other states don't however, and so we're back at the same old point of there being ICAO regs, but them multitudes of state differences. These can be very difficicult to 'stay on top of' for users who are in different countries every day flying :-(

Even with the above phraseolology being used, aircraft positioning visually behind each other (variable gaps!) certainly do not produce the best runway effeiciency, or predicatbility, in my opinion.

Rgds
30W

[FlightPathOBN]

concur,

I am hoping that we can get ADSB in/out sorted out soon enough for a connect into the autopilot...