Glom
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Packing Them In At LHR

Mon Aug 21, 2006 5:01 am

When we landed at LHR last night, as we taxiied, I watched the line of incoming aircraft and noticed how closely spaced they were. I timed the delay between two landings, the first an ERJ and the second an A319. It was probably only about a minute. According to my air law book, the wake turbulence space for medium on medium is 2 minutes.

Are LHR breaking the law?
 
egmcman
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RE: Packing Them In At LHR

Mon Aug 21, 2006 5:30 am

ATC follow strict procedures know what they are doing. Any violations are reported.
 
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scbriml
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RE: Packing Them In At LHR

Mon Aug 21, 2006 6:11 pm

Would an ERJ really count as "medium"?
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scbriml
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RE: Packing Them In At LHR

Mon Aug 21, 2006 6:56 pm

OK, after a little research, I think you're confusing take-off and landing separation.

According to this document (I appreciate it's a few years old now), landing separation is measured in nm while take-off separation is specified in minutes.
http://www.chirp.co.uk/new/Downloads...rbulence%20separation%20landing%22

Certainly, having spent many hours watching landings at LHR, there's no way there's ever much more than a minute between them at busy times. Think about it - if landings were separated by two minutes, only 30 planes an hour could land at LHRcrazy 
Time flies like an arrow. Fruit flies like a banana!
 
ba757gla
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RE: Packing Them In At LHR

Mon Aug 21, 2006 7:01 pm

an erj would still kick up a load of thrust ! would that be BDs ERJs?
 
MRURUN
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RE: Packing Them In At LHR

Mon Aug 21, 2006 8:30 pm

Couldve been LG too!
 
cloudyapple
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RE: Packing Them In At LHR

Tue Aug 22, 2006 12:15 am

Quoting Glom (Thread starter):
When we landed at LHR last night, as we taxiied, I watched the line of incoming aircraft and noticed how closely spaced they were. I timed the delay between two landings, the first an ERJ and the second an A319. It was probably only about a minute. According to my air law book, the wake turbulence space for medium on medium is 2 minutes.

Are LHR breaking the law?

At Heathrow we do not use time based spacings for arrivals. Director clears aircraft onto the ILS at the correct distance based spacings. These spacings are theoretically those written in the book - which are -
HH - Heavy / UM - Upper Medium / LM - Lower Medium / SS - Small / LL - Light

R - Radar Separation 3Nm / Reduced final approach spacing = 2.5Nm

1Nm = 1852m








..
Follower
..HHUMLMSSLL
LeaderHH45568
UMR3446
LMRRR35
SSRRRR3
LLRRRRR


Anything marked R will be 3Nm or given the right conditions during the day 2.5Nm.

Also important is aircraft have to maintain 160kt until 4DME to keep the approach spacing constant, afterwhich they can reduce to final approach speed. But having said that each aircraft type has a different speed profile. So some maybe able to do 160kt but some like the B773 (usually the stretched aircraft) will be a bit faster and some will be a bit slower. The final approach spacing will be adjusted slightly to account for the slight speed differentials.

If you time it again and measure that against the appraoch spacing chart, each Nm equates to approximately 23-25sec.

[Edited 2006-08-21 17:19:43]

[Edited 2006-08-21 17:21:33]

[Edited 2006-08-21 17:22:25]
A310/A319/20/21/A332/3/A343/6/A388/B732/5/7/8/B742/S/4/B752/B763/B772/3/W/E145/J41/MD11/83/90
 
christeljs
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RE: Packing Them In At LHR

Tue Aug 22, 2006 2:32 am

When I was at LHR in June, I was planespotting along the fence when I saw an A320 land, and a B773 right behind, and I mean right behind! The B773 managed to descent the last feet down sooo slowly so that it more or less touched down 4 seconds after the A320 had vacated. I was very fascinated and thought to myself "that was really, really good". It was actually so close behind I thought any moment this 777 is going to have a go around.
Christel A Photography