Avantages of PRNAV approaches

[Sphinx]

Hello all. I have just completed training on PRNAV approaches at LGW. While I understand that the approach enables a reduction in RT workload for ATCO's I'm not sure of the full range of advantages for ATC, nor when it would be implemented.

My thoughts would be that if traffic was heavy radar vectors would have to be used and if traffic is light no-one wants to do a full arrival.

Can any ATCO's explain to a thick pilot, please? Thanks....

[Gonzo]

I'm not familiar with the Gatwick approaches, but at Heathrow they were (are?) being trailled for noise purposes early in the morning.

[Point Seven]

One of the main reasons that airlines are behind these approaches is the fact that by validating them into (reasonably) safe airports, similar approaches can then be devisd into airports in, shall we say, less salubrious parts of the world thereby making it safer and more efficient to get into these airports.

P7

[Spitoon]

enables a reduction in RT workload for ATCO's I'm not sure of the full range of advantages for ATC,Don't know about LGW specifically but I can't see why RT workload would fall significantly.

My thoughts would be that if traffic was heavy radar vectors would have to be used and if traffic is light no-one wants to do a full arrival.
Yup, my thoughts too (certainly for the next ten years - ask me again then when the little black boxes on the aircraft are talking to the little black boxes on the ground and both pilots and controllers are there simply to keep the passengers happy by thinking we can take over if the computers fail!)

The main benefit as far as I am aware is that no ground equipment is required. Some aircraft are coming out of the factory now without ADF rx so if the ILS fails and the only alternative is an NDB the aircraft would have to divert - having a RNAV approach means that most of the time the aircraft could still make an approach. .7 is, of course, correct too - prove the viability of PRNAV at somewhere like LGW and you're one step towards using the same at one of those less salubrious airports or for Cat II/III.

[Flightman]

I'm not familiar with the Gatwick approaches, but at Heathrow they were (are?) being trailled for noise purposes early in the morning.

Still going on Gonzo. Hopefully Cathay and Qantas coming onboard shortly. :ok:

[2miles600feet]

There is a clear benefit in reduction in R/T workload. Pilot is cleared for GWC/MID/BEXIL approach and thereafter controller does not have to issue any headings, levels or speeds.
There is no benefit to ATC when it's busy - as you rightly say you'll get vectors as this is the only surefire way to get consistant spacing. However, the P-RNAV routeings are not (and never were) designed to be used when Gatwick has plenty of traffic offering.
I don't understand the comment about not wanting to fly a 'full arrival'. During the day, you can be cleared for the daytime route which puts you on a 7.2 mile final at 2000ft - Gatwick would not routinely vector you onto anything less. The night procedure gives you a perfect CDA and puts you on a 10.6 mile final at 3000ft. Any less than this and DfT start wagging fingers.

[Sphinx]

Thanks for all the replies. Some interesting stuff in there.

2miles600feet - to address your comment what I meant was something like this........we regularly follow the willo3c on arrival. However if it's not busy we sometimes get cleared from before AVANT to MAY with no speed control to land on 26L. This can cut the arrival time back by about 3-5 mins. If you have to rigidly follow a PRNAV arrival even if it's not busy there is no opportunity to make up any time.

[2miles600feet]

Sphinx

I'd be surprised if the little jink to INGEN adds a great deal of miles. What kills you is the horrible 220kts restriction at INGEN (or TURSA for the BEXIL arrival).

The P-RNAV arrivals were originally planned as 250kts at INGEN/TURSA, but when it was flown in the sim the aerodynamic masterpiece that is the B777 couldn't fly the CDA and slow down without using speedbrake, so BA insisted on the 220kts restriction.

Bit of a shame really. Without this, there was a chance that P-RNAV could have established itself. As it is, monitoring a Gatwick P-RNAV arrival on the tube is possibly the least stimulating activity you can do whilst still remaining upright.

[Lock n' Load]

There seem to be two different things being discussed here - RNAV arrivals (i.e. STARS) and RNAV approaches.
Under the Canadian system, an RNAV arrival can certainly cut down on RT. If there's no traffic or the aircraft happens to fit into a sequence nicely, just clear it for the approach on first contact, or via an intermediate waypoint if there's an operational advantage to doing so. An open RNAV arrival terminates at the "downwind termination waypoint", and if they haven't got an approach clearance by 3 NM before it they just continue downwind, nice and orderly. A closed RNAV arrival (or straight-in) terminates at the FACF and that can be a hassle, as virtually any traffic nearby will lead to the termination of the arrival and out come the vectors. Usually, an RNAV arrival will be followed by a precision or instrument approach just as with vectors or a conventional STAR.

An RNAV approach is a different kettle of fish. They still have to get to the FACF to commence it so there's no reduction in RT unless it's preceded by an RNAV STAR. The real problem is missed approaches, at least in Canada. One company has its own, company-specific RNAV approaches approved by Transport Canada, but the missed approaches bare no resemblance to those for ILS or NDB approaches, and in one case goes into Class F advisory airspace where ATC cannot take IFR aircraft.

[Jerricho]

Ahhh, the RNP RNAV approaches that you mention L&L. Interesting concept on those ones. The fact the missed approach is different from the normal certainly has raised an eyebrow or two. WestJet got together with Naverus and came up with them. Certainly for some approaches with out a precision (Rwy 30 at Thunder Bay comes to mind) they're great, and they have to be approved by ATC traffic permitting. But I do wait for the day where we have a WJA approach, an Air Canada approach, a Perimiter Approach etc.......

[Sphinx]

2miles600feet - thanks for the further explanation.

Interesting point about the CDA and the 777. I don't know if you know what the A320/A321 series does with these restrictions, but if you let the aircraft manage the arrival, as we are supposed to given our SOP's, it will not maintain a CDA. Where both an altitude and speed restriction exist the flight management computer will go for the altitude restriction first then bring the speed back when level. So given our current SOP's I don't think CDA's will be followed very successfully.

If it's any consolation monitoring a PRNAV arrival on the flightdeck is no more stimulating than on the ground!

[BDiONU]

Hello all. I have just completed training on PRNAV approaches at LGW. While I understand that the approach enables a reduction in RT workload for ATCO's I'm not sure of the full range of advantages for ATC, nor when it would be implemented.
UK Government likes the idea of it and a team is working on changing the London TMA airspace to adopt it for part of TC by spring 2009.

BD

[Warped Factor]

UK Government likes the idea of it and a team is working on changing the London TMA airspace to adopt it for part of TC by spring 2009.
BD

Gawd, given the fuss the 250kts speed restriction trial has caused in some quarters I can't wait to see the reaction the above causes :}

WF.