Speed or Distance on Approach?? Fuel Saving

[Heathrowinnit]

During intermediate approach to a well known UK airport, (The clue is in the name) I was wondering whether pilots, from a fuel saving point of view, would prefer to slow down earlier to 180kts, or carry on a little further at 220kts?
I know there are probably lots of other issues like height V distance, but all other things being equal does the average aircraft save more fuel at 180kts or would it be better to fly a couple of extra miles or so at 220kts?
To give you my example I try to give 180ts as aircraft pass through 6000ft unless distance/height are an issue then I try to leave it a little later.
All comments gratefully received.

To build on this I would be grateful for any comments or suggestions as to how, on a day to day basis, ATC could realistically save fuel burn, what can we do to reduce the carbon footprint? There's lots of work on this topic, I'd like to know what we can do now.......

[westinghouse]

the less time you spend in the sky the less fuel you burn.
hence the faster one should travel.:)

[Dream Land]

If passengers wanted to go slow, they would take a train.

[wileydog3]

Been off the 737 and the 'bus now for a few years but as I remember, the fuel burn in LEVEL flight at 220 and 180kts with approach flaps is about the same so no real fuel savings available or lost. So, IF I understand your question correctly, you're asking if I want to go to Newark at 220kts when landing at Philadelphia or stay close to PHL at 180kts. I prefer the latter but again, reality is the time is essentially the same.

The big thing is that the MDs can do 180+ to the marker without an real problem but the Boeings and the Airbi take a bit of work if faster than 180kts and on a 3 deg slope to get configured. 190kt to the marker in an MD-80 wasn't a big challenge but 190 in the 737-400 (old bird) required a lot of work to get stabilized.

The 28APR issue of Aviation Week has a good article on 'green approaches' using 4D technology so the airplanes are back in idle and in a continuous descent. That is the real trick to saving fuel. Not leveling off and driving all over the planet.

[HEATHROW DIRECTOR]

<<To give you my example I try to give 180ts as aircraft pass through 6000ft>>

Is this a new procedure? I thought the reduction to 180 was always given as aircraft turned base leg?

If each different type of aircraft indicates a different "preferred green speed" what do you do about sequencing and achieving the required spacing?

[Roffa]

Heathrowinnit,

If the clue is in the name then when inbound to said airport speed is used tactically by ATC and the reduction from 220kts to 180kts can come at varying points in the approach once off the stack dependent on the traffic situation and the weather (primarily windspeed and the effect it has on groundspeed and radius of turn).

Speed is also used as a separation tool, so...

To give you my example I try to give 180ts as aircraft pass through 6000ft unless distance/height are an issue then I try to leave it a little later.
All comments gratefully received.


... I'm not sure exactly what you mean by that but speeds flown should be those allocated by ATC (unless you specifically state that you're unable to do so) and when a reduction is requested it should be actioned immediately, not at an arbitrary point of your own choosing.

To build on this I would be grateful for any comments or suggestions as to how, on a day to day basis, ATC could realistically save fuel burn, what can we do to reduce the carbon footprint? There's lots of work on this topic, I'd like to know what we can do now.......

For Heathrow, half the number of aircraft using the airport so that there's less/no holding and more optimum profiles can be flown. That would work.

[Del Prado]

Roffa, he/she is ATC. Not sure from your post that you'd picked up on that.

HD, it's getting more and more common to slow to 180kts about 20 miles from touchdown. The newer aircraft (A319s in particular) take an age to slow down. If we ask for 180kts on base leg, they'll still be above 200kts when established, particularly in any sort of tailwind.

Heathrowinnit, the best way we can save fuel burn is to hit the spacing as consistently and accurately as possible. If that requires 180kts at 6000' then keep using it.

[Roffa]

Oops, no I hadn't. Sorry :\

[HEATHROW DIRECTOR]

Del Prado. OK, many thanks for that. When speed control first came in, we used 170kts off the stacks, but this raised questions about fuel wastage, noise, etc., so it was upped to 210 to keep aircraft clean in the intermediate approach. Guess it's back to square one!

[Capt H Peacock]

Unfortunately the answer is several aircraft types multiplied by several different sorts of wind/weather. Some aircraft could fly 220kts clean down the glidepath if they had a 20kt headwind, some aircraft would need to be fully configured for a 10kt tailwind and stuck with 160kts.

We play together in a constantly changing tactical environment, with many successful methods of tackling a similar set of problems.

Bit like golf really. Aren't we lucky:)