QF RNP Trial Cairns

[gulf tango]

QF are trialing new flight path (RNP 2) Cairns using 737-800. Instead of sharp turn left at the threshold Runway 15, flight path follows the Esplanade foreshore south and along Trinity Inlet. Seems no one saw the ad in the paper last September and in March and residents and businesses are up in arms due to noise. Trial goes till Jan 08. How are these trials evaluated? Why do they have to fly a trial, can't they get technical data from Boeing? I know it is about money, money, money.

[OzExpat]

Thanks for that GT, I'd been wondering why the QF 738s were taking a different take-off climb path of late. A "trial" is normally a regulatory tool that's used to gain experience with something new.

Not all aircraft operating in and out of CNS will be capable of RNP 2, so it might also be an opportunity to assess potential problems between those aircraft that are capable of this RNP level and those that are not.

[GaryGnu]

The Departure off RWY 15 in CNS is actually RNP 0.3 (nm).

I was unaware of the "trial" status of RNP ops at CNS. It certainly has the impression of a permanent operation, however, the politics of noise lends a fluid nature to these things.

This episode offers an interesting insight into environmental values. Will people be willing to accept an increase in noise in exchange for an overall lowering of emissions that RNP departures offer thorugh a reduction in track miles?

I suspect the answer to that will provide a tip as to how the politics of global warming/climate change will play out.

I suspect that NIMBYism will trump environmental concern every time.

Ozexpat,
I believe the RNP trial in BNE is assessing how ATC can mix RNP capable and Non RNP "legacy" aircraft.

[Arm out the window]

I believe the trial nature of it is because of the noise issue.
There's already whining in the Cairns Post by people who think they're being personally targeted and that aircraft noise is fine as long as it's not over their house.
There are some noise measuring devices to be used along the esplanade (hospital area I think) and elsewhere to suss out the impact.
There was a flurry of letters in the paper a while back when some bloke took exception to the usual rwy 15 instrument departure - climbing left turn at 400 ft or DER - and said the jets were pointing their exhausts directly at his house.
This then sparked a number of bandwagon-jumpers calling for runways to be moved and so on, in typical 'the airfield was here 50 years before I was but they should move because I don't like the noise' fashion.
Do I sound sympathetic enough?

[Capt Claret]

To where did RWY 15 depart?

[Arm out the window]

Dunno really, but I bet it deliberately rattled cups and windows and put chooks off the lay when it went.

[WynSock]

They can't use this fangled RNP thingy - it fades the curtains.

[gulf tango]

Nobody wants the airport moved or is complaining about EXISTING noise or cares about RNP2 - this is a brand new flight path going straight past properties and businesses that were there before the flight path. Previously aircraft using runway 15 turned left and then went on their way to Hong Kong, PNG, Darwin, Sydney or wherever taking their noise with them.

[Arm out the window]

Granted, but now instead of one lot of businesses and residences having all the noise, it'll be shared round a bit more.
Plus those businesses don't mind taking the money from the tourists coming in on the noisy jets, so maybe it's not all bad.

[Capt.Grumpy]

There's already whining in the Cairns Post by people who think they're being personally targeted and that aircraft noise is fine as long as it's not over their house.

Bunch of whinging pricks, try living here in Yorkeys Knob :cool: We cop it most of the time but the only one I have a problem with is the 4am arrival. That tends to f#ck the sleep about.Just wish there was a 6am curfew though. But I live with it as I knew about the flightpath when I chose to live in Yorkeys :)

[TineeTim]

The key think being missed here is Safety. These approaches and departures are not just about environmental issues and time-saving. This departure is definitely safer than the previous one. Not that they are unsafe, these are safer. That will be how QF argues its case.

[Arm out the window]

They would argue that way, I guess, but their real objective would be to get the jets tracking south a few minutes earlier, wouldn't it?

[Blip]

The key think being missed here is Safety. These approaches and departures are not just about environmental issues and time-saving. This departure is definitely safer than the previous one. Not that they are unsafe, these are safer. That will be how QF argues its case.

I don't think you can argue that tracking up the valley is safer than turning left at the runway end.

In the case of an engine failure, the turn is predicated on a reduced bank angle of only 15 degrees, with the slight degradation in climb performance that a turn causes, taken in to account.

In fact you could argue that it is actually safer to make the left turn after take-off. That procedure takes you out over the water away from ALL the terain in the area. Once heading to the north east, you then have the flexibility to manoeuvere around any weather that might be in the area.

The RNP departure give you NO flexibility in tracking, hence if you find yourself tracking towards a towering cumulus or worse, there is nothing you can do about it until you are above the Minimum Vector Altitude, or MSA.

I seem to remember reading someone making the point earlier that it might be hard to pick out weather hiding amongst the ground clutter that will be prevelent in such a "terrain rich environment" as they call it.

Also consider the fact that there will be much more mechanical turbulence with possible downdraughts in the lee of the hills if the winds are anything above 20 knots or so.

There are two advantages of these RNP departures.
1. Much less distance to travel when bound for cities such as Brisbane, and Sydney
2. Slightly higher take-off weight, given the same wind and temperature.

Safety doesn't come in to it.

[TineeTim]

Safety doesn't come in to it.

Rubbish. Whacking on a 25 degree AOB turn at 400' in a fully laden airliner is NOT safer than whacking in the A/P and performing a series of 10 AOB turns whilst following a magenta line. I take your point regarding weather but that's not all, or even most, of the time. When there are C/Bs around, you go back to the big left hand turn. Day in day out RNP is demonstrably safer. The safety factor WAS a part of the business case used in selling this whole program and you can bet it will be part of the case for continuing it.

[Capn Bloggs]

Whacking on a 25 degree AOB turn at 400'

That's only what AsA says is required to achieve their own stock-standard obstacle clearance SID. Operators are free to come up with whatever bank they like provided their particular aircraft comply with 20.7.1b.

While safety may a bit of it, cost reduction would be why it's being done, I reckon. I tend to agree with Blip. Once you're in the valley, you're stuck. No options apart from hang on, for many miles. Be good fun on a clear day though...

[Capt Fathom]

Once you're in the valley, you're stuck. No options apart from hang on, for many miles

Well, stuck until you get to the MSA of 6500 !

You guys are certainly building this valley into some sort of demon. :uhoh:

[gulf tango]

Tourists? What tourists? Oh, those people who used to go to Cairns for a rest and a sleep in? Not possible now, it's all a whinge and a yawn at 5.38am and again at 5.54am.
Turn? Big turn? Can't turn? Can they only turn in Sydney?

[triadic]

derek zoolander

But when RW 33 approaches are in operation all jets fly right over town(hospital included), at low level, as they have for years, and nobody has a Cairns Post Whingefest.

Certainly the safest option would have been to fly straight out (along the approach path to 33), but in order to provide some balance and some noise sharing, the existing procedure was obviously designed. What has not been mentioned to date is the Max IAS of 220kts. This is designed to get the aircraft high as quickly as possible (and it certainy does) and to me when in CNS recently the RNP departures were a non-event.

Pity the hob-knobs at the north end of the Esplanade seem to be the vocal minority, who can't or don't read the paper. There was plenty of prior notice in the press and on the TV and I understand there are local forums where this and other noise/enviroment issues are discussed and resolved.

No doubt as a result of the trial, the procedure may be amended further (GT - that is one reason why you have a trial). Will just have to wait and see the results of moving the noise sensors to the hospital area.

And GT, the manufacturer does not provide such data for specific ports, that is up to the operator and the regulator. It is also not just about money, but other factors including reduced emissions/environment. Again another reason for the trial. In the not too distant future all RPT aircraft will have RNP capability and we need to learn how to do it best, 'cause you can bet there will be more and not less RNP ops around the corner.

And for a first post, I would be interested in your own motives for the post?? I have been smelling a windup!

[topdrop]

The missed approach path from a 15 RNP approach follows the 15 RNP departure for a while and you only have to climb to 2900ft and then exit the valley via Russell Heads (however at that level you'll be OCTA - traffic is a C152 in the Southern training area :mad:)

The radar lowest safe altitude would let you turn left over water at 4500ft.

Personally, I reckon the valley departures are great - when are Virgin going to start doing them?

[Tankengine]

The flipside of a little extra noise for a few will be a huge redudtion for Yorkeys etc if ATC gives the RNP approach down the creek corridor.[in IMC - same minima as straight in]]:}
Pity it is only 737-800s currently able to do this.:(

[topdrop]

Trouble with RNP P in IMC is if the aircraft in front of you on the ILS does a missed approach, guess where he's pointing - straight back at you on the RNP P approach. :mad:

[TineeTim]

1. Does Dispatch have a note that RNP to be conducted for the sector or is it purely crew discretion?

2. What is the cockpit annunciation on the MCP when the aircraft is cleared for final on the RNP? The reason I ask is that with the cut down plates ATC have, they can not determine the exact track or crossing levels (believe it or not! It's all about copyright and proprietary IP), so ATC are guessing the exact track (as they separate you!) - quite often when cleared for the approach it is common to get a call 'Approaching X Thousand' (the previous assigned level) even though the aircraft has been cleared for the approach.

1. Dispatch know it's a 737-800 and will then plan the RNP. Ultimately, the crew can do whatever they want, however the weights may require the RNP. Supposedly the default SID clearance should be the RNP for QF 737-800s.

2. An 'Approaching X Thousand' after cleared for the approach is an error by the crew. Once cleared for the approach, the minima is set on the MCP regardless of the altitude at which the clearance was received or any previous cleared heights. The biggest advantage in Brisbane is the ability to fly what is basically the river track down to ILS minima without having to go out to 10 miles for the ILS similar deal on 19. Cheers.

[GaryGnu]

Generally the MCP Altitude Window is wound down to approx DA (nearest 100ft rounded up) when cleared for an RNP approach.

Once cleared for the approach, the minima is set on the MCP regardless of the altitude at which the clearance was received or any previous cleared heights.

I don't believe is quite correct.

If:

the altitude clearance prior to the approach clearance is higher than MSA
an early approach clearance is received

the IAF is close to the RWY


Then the crew is left stranded and has no way of ensuring terrain clearance between the MSA and the first Not Below Altitude in the Initial Approach Segment.

Practically that would mean you couldn't descend below MSA until the IAF which could leave you a little high on profile. The simple solution for the flight crew is request a lower altitude to enable further descent until the IAF.

Let me offer an example using the RNP U RWY 19 Approach. The IAF is SINNK which is 11nm from the RWY 19 Threshold. BNE MSA is 3700ft in all sectors (assumes no VOR radials to divide lower MSA sectors). If tracking direct to SINNK and given (for example) "CLEARED 5000ft" followed shortly by "CLEARED RNP APPROACH" then the crew cannot descend below 3700ft until SINNK when they really want to be at 3300ft. I know a 400ft vertical offset is not impossible to deal with but it is not desireable. So a crew may give a gentle reminder to the ATC by calling "APPROACHING" or asking for a lower altitude clearance.

I wouldn't presume to know the exact circumstances that coral speaks of nor is it my intention to tell ATC how to suck eggs. I just want to point out that in some cases an "APPROACHING" call or request for lower altitude after being given an approach clearance is not automatically a flight crew error.

I have had exactly this situation in Canberra.

I would imagine there are procedures in place that ensure a low enough altitude clearance is given that allows an aircraft to commence an RNP approach (once cleared).

Whether to conduct an RNP approach or not is at crew discretion, however, we are encouraged to do so. Personally, I see no point if we are tracking via a 10nm final to a RWY with serviceable ILS.

RNP Departure is also at crew discretion and seems to be the automatic clearance from ATC.