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-   -   speed control on final (https://www.pprune.org/rumours-news/69159-speed-control-final.html)

HEATHROW DIRECTOR 15th Oct 2002 07:10

<<Ask yourself, would you want your family on board an aircraft being operated in such a manner><>

Probably not! I wasn't advocating the practice, merely stating the sort of situation which occurs when we say "No speed control". I watched several aircraft closely on radar yesterday during quiet traffic conditions; eg there was a 757 doing over 190kts at 5DME too but we're always told that the 757 really needs to slow down early.... After the very interesting discussions on here I'm simply saying that, given the opportunity, many crews will fly speeds considerably in excess of those which ATC would normally impose in the approach sector. It's becoming obvious that some pilots will not adhere to the speeds we impose (even though they've read it back?) whilst other pilots of the same type - possibly with the same airline - will fly much faster. So where's the "standardisation"?

I'm still thinking hard about the comment from the 777 chap. We routinely use 170kts to 4DME for 777-300s because that's the speed we've been told that they want - and we know from experience that they do'nt slow down!! I've never known any 777 pilot query "160kts to 4DME", nor do I recall one ever asking for a slower speed so do I assume that all of these guys are lying when they read-back? Some of you ought to watch 777s and other heavy jets doing their "own thing" early in the morning.

A4 15th Oct 2002 09:02

It is interesting the way some people seem to interpret "no speed control" (sounds like some the approaches described in this thread! ;) )

It would appear that some take it as free reign to come screaming down the ILS at 200+ knots to 4D and the throw out the anchor to get it all back together in time for landing. If I'm given "free speed" I will use that to adjust my descent accordingly and usually start to reduce to 250 knots at about 6000' but I still aim to be 210 knots Flap1 at about 10D and take F2 just before the glide - if you don't the only way to get the bus to slow is the gear. After that it's just a normal approach. Boring? sensible? predictable? No, Yes, Yes.

A4 :)

mcdhu 15th Oct 2002 09:25

I'm with you, A4. Why give yourself - and the PNF - the hassle of wondering if you have overcooked it or not?

Furthermore, in a jet aeroplane the last 30 track miles will take you 9 mins, give or take a minute, whatever your antics with the speed, so why bother?

Cheers,
mcdhu

Victor Mike 15th Oct 2002 09:33

Quick input re the 757 on finals. Required Vapp varies dramatically with weight, hence a very heavy 757 (oops took too much fuel again) has no problems with 160 to 4. A very light one with not much headwind Vapp could be 120 kts and no chance of slowing down in 4 miles.
regards
Victor Mike

Julioviana 18th Oct 2002 11:47

Hello, this is an answer to Lazlo´s letter about speed. Here in Spain we understand (let me know if you consider the matter in a differente way), that when we clear a traffic for an approach the limitations in speed instructed before are no longer valid. Unless otherwise stated.
For example if I ask an aircraft to maintain 180 knots and later on I clear him for approach, he no longer has to maintain 180 unless I ask him to keep that speed until 8 dme.

Thank you

Cough 18th Oct 2002 15:45

Following from VM's reply - From a 737/4 perspective. (The weight thing is very important)

Three situations -

Firstly when very light (doesn't happen often out of LHR) then we may have to cheat (just a little, say 4.5d) to make the 1000' gate (bear in mind for BA this is a Radio Altitude...come back to this one.) Now this is a double whammy situation coz you decelerate early, and then fly finals slow too..Some of us try to warn director if we are in this category..

Secondly, when at moderate weights then 170/4 is great, and appreciated, as we don't have to dump the gear. May cruise past the 4d point decelerating through about 165, but nothing too early.

Thirdly, when we are very heavy, then we move another 10 knots faster on the flap/speed schedule. That means gear comes down when passing 180kt. This leads to the whole approach typically being flown gear down once a deceleration is asked for.

Overall my vote would be for 170/5d. Don't know how the buses would cope with that, but the 737 would be ok.

Coming back to the 1000' point. We have to 'adjust' to be stable by 1000' radio altitude, not a height of 1000'. At LHR this isn't an issue, but try LGW 08, or GLA (both ends), ABZ 16 then you have to correct a little.

Anyhow, enough rambling...Fri night, time for something a little different...


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