LHR 160 till 4dme

[sickto the backteeth]

Followed a B77W belonging to a Hong Kong based airline into LHR yesterday onto 27R. In the LAM hold they were asking for 165 till 5dme then 160 at 4 from the controller. This was approved. By chance, I met the crew signing in at the hotel and politely asked "why" the non-standard requests ? "Fuel saving and noise abatement tactics was the reply".

Anybody else do this ?

[sierra_mike]

if this few extra knots enable you to use a lower flap setting (less fuel burn, less noise) for a considerable amount of time why not ask (ATC workload permitting)?

[misd-agin]

They're either at F20 or greater than F20. Maintaining 165 kts instead of 160 kts won't change the required flap setting.
The difference in fuel burn between 165 kts vs 160 kts is minimal, especially when it's for maybe 500-1000' (2-3 nm).

[DuneMentat]

Could well be the difference between being at GearDown and Flaps > 20 vs F15

[mbcxharm]

165 vs 160 could mean the difference between needing to lower the gear or not.

e.g. at 235T, Vref = 145. You can maintain 165 kts with F15 (Vref+20), however to decelerate further you would have to select G/D F20 and then a further stage to F25/F30 which would allow you to reduce to 160 kts. If this was required at some distance before your stabilisation point then this would be undesirable, hence the request to maintain 165 kts.

If they were lighter, e.g. at 220T landing weight, Vref = 140 and they would have been able to maintain 160 with F15.

[mbcxharm]

DuneMentat beat me to it!

[Jumbo2]

Generally it are the Euro Wings crews who don't maintain their assigned speed and slow down way early without telling ATC. Have done a few go-arounds being the aircraft behind them. It's a pity LHR controllers don't send the offending aircraft around but the unlucky ones behind it.

[Check Airman]

165 vs 160 could mean the difference between needing to lower the gear or not.

e.g. at 235T, Vref = 145. You can maintain 165 kts with F15 (Vref+20), however to decelerate further you would have to select G/D F20 and then a further stage to F25/F30 which would allow you to reduce to 160 kts. If this was required at some distance before your stabilisation point then this would be undesirable, hence the request to maintain 165 kts.

If they were lighter, e.g. at 220T landing weight, Vref = 140 and they would have been able to maintain 160 with F15.

I don't fly the 777, but what prevents you from selecting F20 with gear up? Do you get the gear warning horn in that configuration?

[DaveReidUK]

Generally it are the Euro Wings crews who don't maintain their assigned speed and slow down way early without telling ATC. Have done a few go-arounds being the aircraft behind them. It's a pity LHR controllers don't send the offending aircraft around but the unlucky ones behind it.

Yes, that does seem a tad unfair, especially as the controllers can see everyone's IAS nowadays.

Having said that, the thread is about an operator who wants to slow down late rather than early.

[White Knight]

Yes, that does seem a tad unfair, especially as the controllers can see everyone's IAS nowadays.

Well, they can see what IAS you've got selected...

[Max Angle]

Actually I think the only selected (as opposed to indicated) data that is displayed to the controller is altitude.

[frieghtdog2000]

Try this in an empty B757 with min fuel (VREF 108) - it's doable but needs planning and you need to tell the controller of the final V APP so that he can slow the following aircraft.

[mbcxharm]

I don't fly the 777, but what prevents you from selecting F20 with gear up? Do you get the gear warning horn in that configuration?







Nothing prevents you selecting it and no you don’t, but F20 has the same manoeuvring speed as F15 (i.e. Vref+20). To slow further (to 160 as in the example I gave previously) you need F25/F30 which would sound the gear warning if selected before the gear is down.

[DaveReidUK]

Well, they can see what IAS you've got selected...

No, they can see what IAS you are achieving.

[Check Airman]

Nothing prevents you selecting it and no you don’t, but F20 has the same manoeuvring speed as F15 (i.e. Vref+20). To slow further (to 160 as in the example I gave previously) you need F25/F30 which would sound the gear warning if selected before the gear is down.
Got it. thanks

[unitedabx]

At 4 DME ATC can monitor not only your actual IAS but also what you have selected in your MCP speed window. Bi-annully ATC publish the statistics for who is complying and who is not. Interesting reading.

[vilas]

More likely answer is being Hong Kong based they are used to it. HongKong ILS 25 L/R requires 180kt from 15DME to 7 DME and then 160-150kt at 4DME.

[DaveReidUK]

At 4 DME ATC can monitor not only your actual IAS but also what you have selected in your MCP speed window.

Unless that's a relatively recent addition, I don't think you're correct. Which BDS are you getting selected speed from ?

[Skyjob]

Many aircraft have a similar issue regarding speed control, like the 737NG, depending on weight you can maintain 160kts or a little higher may be required. As all operators are environmentalists and noise pollution specialists (citizens under flightpath) would prefer us pilots to fly with gear up until 4/5nm, then a slightly higher speed is better than the alternative option.

In regards transponder and ADS-B:

ELS (Elementary or Basic Surveillance Functionality):

Aircraft identity unique
Altitude reporting in 25ft increments
Transponder capability report
Flight status (air/ground)
SI code

EHS (Enhanced Surveillance)

FMS Selected Altitude
Turn Information: Roll Angle, True Track Angle, Track Angle Rate
Ground Speed
Magnetic Heading
Achieved Indicated Air Speed (IAS)/Mach (not selected/commanded)
Barometric Climb Rate
TCAS RA Information

[DaveReidUK]

EHS (Enhanced Surveillance)



FMS Selected Altitude
Turn Information: Roll Angle, True Track Angle, Track Angle Rate
Ground Speed
Magnetic Heading
Achieved Indicated Air Speed (IAS)/Mach (not selected/commanded)
Barometric Climb Rate
TCAS RA Information




Indeed.

You also get Baro Pressure Setting, as part of the Selected Vertical Intention (BDS 4,0) message and TAS, as part of the Track and Turn (BDS 5,0) message.

But none of the standard EHS messages contain Selected Speed, hence my doubt re the previous poster's assertion that ATC can see that.

[unitedabx]

Checking info on "MCP selections".

Selected IAS NOT transmiitedonly actual IAS.

Apologies Gents.

[LeadSled]

Folks,
One airline from SE Asia is not happy about config. changes on "short final" so flies with Flap 30, gear down all the way from about 3000 ft, rather defeating the noise minimization aspect of the procedure.
Tootle pip!!

[Dan Winterland]

One airline from SE Asia is not happy about config. changes on "short final" so flies with Flap 30, gear down all the way from about 3000 ft,

Many airlines from that part of the world have rigid stabilisation criteria and no mercy when it is found these have been broken. The guys aren't taking a chance of being punished. An unintended consequence of the rules.

[vilas]

One airline from SE Asia is not happy about config. changes on "short final" Short finals is very vague. The airline may be too strict about Stabilized approach by 1000ft. so one can push it up 1500. Three thousand is way too much. I don't know how the airline can accept that.

[LeadSled]

Short finals is very vague. The airline may be too strict about Stabilized approach by 1000ft. so one can push it up 1500. Three thousand is way too much. I don't know how the airline can accept that.
Vilas,
There was a reason why "short final" was in inverted commas.
It was/is not a matter of the airline accepting, but requiring, the aircraft be in the landing configuration, checks complete, at approx. 10nm/3000 agl.
Dan in the previous post "gets it".
Tootle pip!!

[RexBanner]

Actually I think the only selected (as opposed to indicated) data that is displayed to the controller is altitude.

Nah they can definitely see what speed you have selected on the MCP. Hence why flying an approach with managed speed into Heathrow (as long as S and F speeds comply with the speed control given) confuses the hell out of them and often they’ll ask you to confirm your speed.

[DaveReidUK]

Nah they can definitely see what speed you have selected on the MCP. Hence why flying an approach with managed speed into Heathrow (as long as S and F speeds comply with the speed control given) confuses the hell out of them and often they’ll ask you to confirm your speed.

Then allow me to ask you the same question that I asked the previous poster (who subsequently decided that selected speed wasn't displayed, after all):

Which BDS are you getting selected speed from ?

I can't find anything in the Mode S/EHS spec that has provision for MCP selected speed. While selected altitude has obvious benefits in providing potential early warning of a possible level bust, I'm struggling to see similar benefits for an approach controller who already has access to your IAS and, as noted above, will likely ask you what you're doing if you appear to be ignoring a speed instruction.

Can anybody provide a definitive reference to any recent changes to the Mode S/EHS spec that make this provision?

[RexBanner]

Why are they asking you to confirm your speed then when you’re flying managed speed which, quite coincidentally, is the only time they ask you that question?

[KriVa]

I’m not at LL, but Mode S/ADS-B functionality is the same for everybody, I can confirm we(ATCOs) can’t see your selected speed.
However, if you’re doing something different than preceding or succeeding traffic (even slightly different), it does stand out. So if they ask you to maintain 160, and you keep 165, that difference will be noticeable after a short while, if the others are doing 160 exactly.

[DaveReidUK]

I’m not at LL, but Mode S/ADS-B functionality is the same for everybody, I can confirm we (ATCOs) can’t see your selected speed.

Thanks for the definitive response and explanation.

[Wally777]

Once had a 63 000kg payload on a B77W and needed to configure fully for landing with F30 at 4000' joining the GP to try and achieve the ATC speeds. - Not ideal.

[Skyjob]

I’m not at LL, but Mode S/ADS-B functionality is the same for everybody, I can confirm we(ATCOs) can’t see your selected speed.
However, if you’re doing something different than preceding or succeeding traffic (even slightly different), it does stand out. So if they ask you to maintain 160, and you keep 165, that difference will be noticeable after a short while, if the others are doing 160 exactly.


And this is where the problem is, ATC expect us to fly exact speed of eg 160, but aircraft limitations due eg landing weight prohibit this to be done unless the big anchor is dropped down causing a lot of noise which no one wants.
Better would be a dialog with airlines, so that types unable to fly 160 at MLW are planned for at the appropriate speed they can fly without dropping the gear, eg 165...

[737aviator]

Happens elsewhere. LGW Atco's know we often want 170-5 as with the short field performance mod we almost always would need to drop gear and F15 for 160. Drop the request with director on checkin and we usually get it.

Dialogue with the airline(s) resulted in STN now requesting 165 to 4 instead of 160, enabling a certain 737 operator to keep the gear up till 4 miles with flaps 5/10.
In other airports that request 160 I'd usually ask if 16x is ok and usually they're happy.

[Gonzo]

Heathrow ATC can only see actual IAS, not selected.

Heathrow AIP entry gives usual speeds to expect, including 160 to 4DME. If this is not acceptable, then as requested in the AIP please inform Director on first contact and we will accommodate a different speed on final.