jbernie
Topic Author
Posts: 206
Joined: Wed Jan 10, 2007 10:09 am

QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 8:47 am

Quote:
Big passenger jets are set to glide into Auckland International Airport from next month in a trial to save fuel and reduce air pollution.

Airways New Zealand said it had been working with Air New Zealand and Qantas for jumbo jets to reduce fuel use and emissions as the aircraft came into land.

The procedure was safe and flights into Auckland would be spaced to allow a glide descent into the airport from their top of descent point, Airways New Zealand main trunk manager Lew Jenkins said.

"These glide descent profiles will be flown with the aircraft engines set at idle, thereby significantly reducing fuel burn and emissions," he said.

http://www.smh.com.au/news/World/Jum...land/2007/03/28/1174761518480.html

Very interesting concept, I would also be interested in how much noise reduction will occur. Sometimes you don't realize how much noise there is until it isn't there. It will also be interesting to see if the concept works well enough to keep in place and if it will be tested elsewhere. I am assuming the flight path would be over water for those just in case moments?

For those more in the know, is there a real difference between a glide "landing" and a glide "descent"?
 
MCOflyer
Posts: 7086
Joined: Tue Jun 13, 2006 5:51 am

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 8:50 am

This will be intresting. At least the engines will be on.

MCOflyer
Never be afraid to stand up for who you are.
 
kiwiinoz
Posts: 2000
Joined: Mon Oct 10, 2005 3:07 pm

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 9:31 am

This has been previousely tested in other places, including SFO and MEL.

I presume it would only work as a permanent concept at low volume airports? Or at off peak times? Requires uninterrupted glide path and this would be impossible at some airports.
 
BOE773
Posts: 413
Joined: Wed Mar 08, 2006 6:02 am

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 10:19 am

There was an excellent article written about this several weeks ago in one of my AWST mags. which I have since passed on to others. This is not a new idea by the way. WN and several other carriers have been doing these descents.

Required Navigation Performance procedures (RNP) are currently being practiced by Alaska and Horizon airlines. This system uses HUD coupled with GPS. RNP is a type of RNAV that uses GPS positioning, inertial reference sys; and (in some cases) DME to contain an aircraft in a narrow corridor of airspace. It includes onboard nav monitoring equipment to alert the pilot if the tight tolerances can no longer be met. With RNP, aircraft can navigate thru mountain valleys safely. Special training for aircrew and authorization is required. This system could spell the eventual demise of ILS systems.
 
highflyer9790
Posts: 1189
Joined: Thu Jul 07, 2005 1:21 am

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 10:33 am

I thought TOD points were always used to save fuel? or are we talking about an all out flight idle descent to touchdown?
121
 
ardian
Posts: 506
Joined: Fri Oct 06, 2000 3:15 am

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 10:42 am

I believed AMS was also testing this (correct me if I'm wrong).
 
BOE773
Posts: 413
Joined: Wed Mar 08, 2006 6:02 am

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 11:39 am

Quoting HighFlyer9790 (Reply 4):

Yes flt idle, all the way from TOD to the button.
I didn't know about AMS doing testing.

I find that an excellent source for good info is Aviation Week and Space Technology (AWST) mag.
 
jasond
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Joined: Fri Jul 10, 2009 5:23 am

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 1:35 pm

Quoting KiwiinOz (Reply 2):
I presume it would only work as a permanent concept at low volume airports? Or at off peak times? Requires uninterrupted glide path and this would be impossible at some airports.

Interesting that the story appears to contradict it itself on this point (certainly the NineMSN version of it anyway). The story states Auckland was chosen because its busy BUT QF and NZ 747's were chosen because they arrive at less busy times of the day. Also it can't be a true glide, you need some power applied to stablise and correct and anomolies in the final approach unless of course the maneouvre was perfectly executed in which case it would effectivily be an highly optomised autoland, wouldn't it?
 
Mir
Posts: 19491
Joined: Mon Jan 05, 2004 3:55 am

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 1:53 pm

I believe the final approach would have to be flown under power, otherwise the descent angle would be too steep.

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
PITrules
Posts: 2109
Joined: Fri Jun 23, 2000 11:27 am

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 3:23 pm

The flight idle portion would be from the TOD to the FAF. From the Final Approach Fix (last 5 miles), the approach would be flown as usual, with the engines spooled up.

I agree these procedures are only useful in uncongested airspace, as these procedures would need to be flexible for all aircraft to make use of them. Different aircraft have different glide ratios. Even identical aircraft have different glide ratios at different weights. Add into the mix different winds from day to day, and a flight idle decent will have a different profile every time.
FLYi
 
kiwiinoz
Posts: 2000
Joined: Mon Oct 10, 2005 3:07 pm

RE: QF & Air NZ 747s To Test "glide Descents"

Wed Mar 28, 2007 3:53 pm

Quoting Jasond (Reply 7):
Also it can't be a true glide, you need some power applied to stablise and correct and anomolies in the final approach unless of course the maneouvre was perfectly executed in which case it would effectivily be an highly optomised autoland, wouldn't it?

It's true....some power has to come on at some stage, but I guess there is potential for the engines to be on idle for 90% of the descent if it really is uninterrupted.

Perhaps they should try one of those Sarajevo landings.....do they need power. That would make for a good video with a 747

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