PPRuNe Forums - Continuous Descent Approaches

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But lets say you're at 220kts...you'd want 1100fpm for 300ft/nm descent. Idle power, in the A320 will typically give around 1300fpm-1500fpm (apologies if you're already well aware!) Admit it's not much power though to reduce by 200fpm-400fpm.

Not sure about other bus drivers but I find the vertical management is pretty useless below 10,000ft when wanting to achieve a CDA, given it programmes a level flight portion to slow down. Some work mates swear by it though and prefer to get down to about 4000ft and choose V/S 300fpm in the last 1000ft before G/S intercept....does this doesn't qualify as a CDA?

I must get it right about 4/5 of the time I fly into LGW- twice a day. However, though we have very primitive nav kit, we do have a copy of the booklet LGW sent us with the tables in. That certainly helps, as does the ability of the 146 to steepen it's descent if you get it wrong.:p

I often have to fly about 2-300fpm to stay sensible, but If I've got the ones that allow it, I can set up a couple of mythical base leg and long final points and give them a vertical gate to help- that's with a GNS-XLS as well, not a fancy modern FMS. Just using every tool in the box to help.

Obviously an FMS based approach would help, but sometimes you get silly long downwind legs to alter spacing for departures that bugger up any hope of getting it right. Not our fault but does that affect the published stats?

Nice thread.

I think at LGW, the normal min ROD (500fpm) doesn't apply below 6000'(?)

Also it seems there are two flavours of controllers at LGW, the good and the excellent. With the good ones you have to watch your track miles v.closely and dust off your 3x table. With the latter, just do as you're told and it works beautifully. The problem is of course, you don't know which flavour you've got until it's too late!!!

I find that the G/S indicator on the standby horizon "wakes up" before the one on the PFD/ND, this can help with your VSing to keep the CDA going.

Er - not mythical if you're flying into Manchester - it's in the UK AIP to descend at min rate of 500ft per min.
CDA's are done at there 2200-0700 though.
However - you are quite right for Gatwick - it says that the pilot decides the best rate of descent required to achieve continuous descent:)

louby

Quote:

it's in the UK AIP to descend at min 500ft per min

- which takes me back to post #17 - I KNOW I was told (by BA) there was no descent rate limit in the the TMA for CDA, but I CANNOT find an official reference to it. Does anyone have one?

Think I crossed there with your edit, louby - are you saying that IS in the AIP?

Each airfield has their own procedures - you can look up the relevant airfield on the AIP web site, I just had a look! www.ais.com

louby

ARGH crossed again!!!
Yes ! Go to the txt bit for the appropriate airfield and it will be in there:p
louby

That should be ais.org.uk.

...and there it is,

AD 2-EGKK-1-18 para 5.a

..........and what is a chap to do?

AD 2-EGCC-1-15 2.d and e.2

...whereas Stansted says nothing.

Sounds as if the airfields need to sort this out. Any ATC comment?

Thanks BOAC - I got booted as I realised that - and I thought having broadband meant never getting booted :{

Anyway - hope that helped you find the reference you were looking for

louby

....we must stop crossing like this:)

Rainboe, you've got me there - I can't find a reference that specifies a minimum rate of descent (I'll get back to you!) However......

ICAO 8168 1.4.1.7

min rate of descent for Cat C/D/E in the final approach segment is 590 ft/min.

UK AIP AD-2 EGKK 1-15

"....a descent will have deemed to have been continuous provided that no segment of level flight longer than 2.5nm occurs below 6000' qnh and level flight is interpreted as any segment of flight having a height change of not more than 50' over a track distance of 2nm or more"

UK AIP AD-2 EGKK-1-18

"on receipt of a descent clearance the pilot will descend at a rate he judges will be best suited to the achievement of a continuous descent, the object being to join the glide path at the appropriate height for the distance without recourse to level flight"

This is fun isn't it?

Fred.

From the UK AIP:

Quote:

2.2 Minimum Rates of Climb and Descent
2.2.1 In order to ensure that controllers can accurately predict flight profiles to maintain standard vertical separation between
aircraft, pilots of aircraft commencing a climb or descent in accordance with an ATC Clearance should inform the controller if they
anticipate that their rate of climb or descent during the level change will be less than 500 ft per minute, or if at any time during such a
climb or descent their vertical speed is, in fact, less than 500 ft per minute.
2.2.2 This requirement applies to both the en-route phase of flight and to terminal holding above Transition Altitude.
Note: This is not a prohibition on the use of rates of climb or descent of less than 500 ft per minute where necessary to
comply with other operating requirements.

My reading of this is that flying at less than 500fpm is not prohibited, as long as you have informed ATC. The requirement to inform ATC is removed when flying below Trans Alt, as per 2.2.2. Therefore my conclusion is that one is perfectly entitled to fly at less than 500fpm below the Trans Alt whenever it is required. The "Note" in 2.2.2 would seem to reinforce this, as a CDA is certainly an "operating requirement" at some airports.

I have also come across a document called "Noise from Arriving Aircraft - An Industry Code of Practice", dated Sept 2001, which has the following line:

Quote:

35. The instructions in the UK AIP that referred to a minimum descent rate of 500 fpm
are to be clarified, enabling extended descents in line with CDA to be achieved
without need to notify ATC of lower rate of descent below transition altitude. This
will come into effect from 4 October 2001.

I think note 2.2.2 from the AIP is this clarification. Admittedly it's not overly clear that it is applying to CDA's, but I think a literal reading of it allows for less than 500fpm when required.

Well played Sir!

Now why couldn't I find that........:confused:

Quote:

but below Transition Level, CDA takes over.

- re-read post #34. 500fpm MINIMUM applies at EGCC for CDA approaches and, I think, at EGSS. The 'Code of Practice' has not yet been fully implemented.

Quote:

re-read post #34. 500fpm MINIMUM applies at EGCC for CDA approaches and, I think, at EGSS. The 'Code of Practice' has not yet been fully implemented.
Today 11:44

So I'm gonna get a bollocking for doing 400fpm to splodge the G/S and MCP alt..rather than flying level for a bit?
Throw in a tailwind in the wrong place...and a bit of anti ice, and this rule seems to be bloody idiotic:ugh:

I don't thinks so - I don't:) . I'm just pointing out the 'letter of the law' regarding descent rates.
PS a tailwind will help you.:cool: