Continuous Descent Approaches
 

I know that CDAs are encouraged for operating into Heathrow and that ATC do quietly monitor to see if you comply and produce statistics to show who the best operators are. Just wondering if this practice is the same at Gatwick or any other UK airport for that matter?

CDA is in operation at LHR/LGW and STN. Manchester as well I think. As for who is the best operators, well home grown airlines regularly top the charts. Currently 87% of all daytime arrivals were CDA complaint, with 92% at night. LHR figures. :ok:

Monthly statistics are produced for 3 night-time, key performance indicators (KPI) for Heathrow, Gatwick and Stansted; CDA is one of those KPI. It is particularly sensitive at Heathrow because of the Westerly approaches being over central London. However, during the early morning period (06:00) CDA tend to be less accurately applied in order that simultaneous approaches to both runways can be safely delivered. (When the final director is landing traffic at rates in excess of 50 per hour it is far safer to turn in using vertical separation. That means one side cannot have a full CDA.) It is a question of delivering the required capacity.

Point 4

Thanks for that. Is every approach 'monitored' so to speak or are statistics based on random snapshots?

I believe every appoach is monitored. We get a breakdown of how many aircraft had a CDA etc.

.4

Every arrival ( and departure for that matter ) is recorded in our Noise and Track Keeping system. The system automatically calculates for CDA and on/off track.
Also, the previous comment about the 06:00 hour ni longer applies. Historically that was the case, but ove the last 18 months the 06:00 to 07:00 average is better than the 07:00 - 23:00. Last month it was 1% better at 88%.
A sincere well done to all concerned. :D

<<that ATC do quietly monitor >>

I don't think that is true, unless things have changed. When I was working the monitoring was carried out by the airport authority, which is a wholly different entity, and they sent results regularly to ATC.

Thanks for all your comments - interesting and helpful. I detect that the CDA practice might be well known into Heathrow but less so for the other airports.

From a pilots point of view I have only seen a brief blurb on it in our BALPA magazine 'The Log', however maybe an AIC or something similar might be in order to improve awareness.

East midlands also monitor and produce CDA statistics-for the full 24 hour period, this is done by the environmental department, using the noise and track monitor equipment, and ATC are briefed on the percentage achieved and the airline percentages (currently 83%)

The 2nd arrivals Code of Practice is currently at the printers. X'000 of copies being printed and will be distributed to airlines, ATC and other interested parties.

CDAs
 

CDAs are in place at Heathrow, Gatwick and Stansted, they have been for years. The BAA, NATS, DfT, Airlines and the CAA all co-wrote the Arrivals Code of Practice in 2002. Since then CDAs have become the primary noise reduction measure for arriving aircraft. Since the code was originally written it has been 'adopted' by other UK airfields, Europe and beyond. Eurocontrol have started a group looking at harmonising CDAs across Europe and using the Code of Practice as the guideline document. As Flightman points out, version 2 is at the printers and will hit the streets imminently.

Other work involving CDAs are at Manchester (at night at the moment), Luton on both 08 and 26, as part of their recent airspace extension, NEMA (P-RNAV) but also radar vectored approaches. Also as part of Sustainable Aviation, Commitment 15 is looking at a CDA outreach programme across the UK by the end of 2006. This programme is in progress, and will have updates by the end of the year.

In it's most basic form, a CDA is keeping an aircraft as high as possible for as long as possible. It's not rocket science!

In summary, CDAs are here to stay and they will affect controllers and operators. Doing nothing is no longer an option!

PS. Accountants love CDAs, as they save fuel, emission &, engine wear.

CDAs also now in use for Cardiff and Bristol .

Any tips on how I could get a copy of the 2nd Arrivals Code of Practice. Would anyone be kind to post a link to it if they have one?

The code is in the process of being published. When it is full copies will be distributed in limited numbers, but an abbreviated version will be sent out to a much wider dostribution, i.e. Pilos and Controllers. There will also be .pdf versions available on the internet. The file will be hosted on the DfT website but there will be links from the CAA, NATS, BA, Easyjet etc. websites. The DfT will also push out a press release, so the launch will be high level. If I know when the launch date is I'll post on this forum.

...and think that the majority of the pilot fraternity strive to fly CDAs whenever possible, wether the practise is formalised at the given airport or not - especially with todays fuel prices :ok:

Pheighdough - I believe that there is a bit more to it than keeping the aircraft as high as possible for as long as possible :} ...or is that the reason all arrivals into LBA are kept so high that we rely on high speed below 100??? Anyway, the result is far from what you could term CDA, and far from fuel & noise efficient :{

Empty

Don't know what your referring to, in your last comment, but CDA has proven noise and fuel reduction benefits. Off the top of my head I think for a 744 its upto -4dB on the ground, and from 6000ft a 1t savign in fuel burn for the same a/c type.

In many ways CDA is simply "higher for longer" but not so high that the situation you appear to be in occurs. An ideal CDA is a constant 3 deg descent to touchdown. The eary morning P-RNAV arrivals into LHR have all achieved this, going out to about 35 miles, which is as far as our monitoring system lets us go.

The existing Code of Practice doc can be downloaded here;

http://www.caa.co.uk/default.aspx?ca...87&groupid=321

Its towards the bottom of the page.

I believe the revised code will be available in 4 - 6 weeks.

But...
 

The last few miles of the approach are still flown at a relatively high power setting with the autothrottles sawing away, flap and gear dangling creating drag etc. That's where the noise is at its worst. Try living in Richmond-on-Thames, Twickenham or Hounslow. You get woken up at 05.17 and that's it, then. We get woken up by the reverse thrust at the aforementioned 05.17 if there's a NW wind component and we're 10 miles from LHR.

I've no doubt CDAs have gone some way to improving the noise environment further out but we've an awful long way to go to making significant improvements in the final approach sector.

Years ago there was a suggestion that the ideal would be the selection of idle power at top of descent with NO additional power applied until shutting down on the gate. Still a dream, I think.

We've a loooooong way to go to making an urban airport neighbour-friendly.

TheOddOne

And another thing...
 

Whatever happened to the idea of moving the 27L/R thresholds in? Moving them west by a kilometer would still leave 3,000 metres of LDA on 27R, surely enough for everyone? It'd make the turnoff much nearer to T5, as well, shortening taxi times for BA.

This'd raise the approach by a couple of hundred feet. Might make a difference to some people's lives.

TheOddOne

The 27L threshold can not be moved because of the buildings around T4/Central area, plus it would move the CAT III holding point miles from the end of the runway. The 27R threshold would move to a position over the tunnel, and this is not structually strong enoght to have aircraft touching down on it, although it can take aircraft over it.
What seemed a good idea is not so simple...

CDAs

In the company I fly for CDAs are almost regarded as a norm wherever we go and certainly at places such as LHR, LGW, BRS, EMA, STN.