View Full Version : Heathrow Approach
PhineasC
30th Jul 2012, 07:56
There is little if any spare capacity at Heathrow but is there any time of the day or day of the week when Heathrow approach is particularly busy?
DaveReidUK
30th Jul 2012, 08:37
There is little if any spare capacity at Heathrow but is there any time of the day or day of the week when Heathrow approach is particularly busy?
If it helps, Summer 2012 Runway Scheduling Limits are as follows:
05 38 25 63
06 39 46 85
07 37 44 81
08 40 43 83
09 40 41 81
10 41 42 83
11 39 41 80
12 43 43 86
13 43 43 86
14 41 44 85
15 42 42 84
16 43 43 86
17 44 44 88
18 43 44 87
19 38 38 76
20 44 37 81
21 21 31 52
(UTC hour, arrivals, departures, total movements).
Of course the above isn't necessarily what happens on the day.
Given that between 0600 and 0700 local, parallel approaches are made onto both runways, would that not be, in practice, when the greatest number of approaches per hour are made.
The figures above show theoretical scheduled slots, but for the overnight inbound flights there are a good many that typically arrive significantly early but hold waiting for the 0600 release (of course, all the BA ones then sit on the ground after landing waiting alongside T5 for someone to saunter over and turn the stand guidance on).
DaveReidUK
1st Aug 2012, 18:32
Given that between 0600 and 0700 local, parallel approaches are made onto both runways, would that not be, in practice, when the greatest number of approaches per hour are made.
That would seem to make sense, but it's not actually what happens in practice.
In June, for example, there were on average just over 38 landings per day in the 0600-0700 period. But in the evening period (1800-2100) that figure rose to an average of over 41 landings per hour.
The reason, of course, is that pretty well all of the 0600-0700 arrivals are heavies, with correspondingly greater wake separation requirements than a stream of A320s or 737s.
WHBM,
The 0600-0700 hour when we land on both runways we usually provide 6nm spacing to each runway, generally staggered by 3nm, so overall the airport has 3nm spacing.....the equivalent to a string of Medium category aircraft landing on one runway.
DaveReidUK
2nd Aug 2012, 23:03
The 0600-0700 hour when we land on both runways we usually provide 6nm spacing to each runway, generally staggered by 3nm, so overall the airport has 3nm spacing.....the equivalent to a string of Medium category aircraft landing on one runway.
Does that mean that, in theory, there is spare capacity for an additional 3-4 landings in the 0600-0700 hour, or is that an over-simplification ?
Dairyground
2nd Aug 2012, 23:31
The 0600-0700 hour when we land on both runways we usually provide 6nm spacing to each runway, generally staggered by 3nm, so overall the airport has 3nm spacing.....the equivalent to a string of Medium category aircraft landing on one runway.
Why is separation maintained in terms of distance, rather than time? Using fixed distance separation, strong winds, with the resultant reduced speed over the ground, increase the time between aircraft passing over a fixed point, such as the runway threshold, and thus reduce landing rates.
DaveReidUK,
The radar minima in this case is 2nm on the diagonal. 2.5nm is usually the lowestes aimed for. The issue being that from 0620 onwards when departures begin, we need a minimum of 6nm gaps to the departure runway, which only works if you provide 6nm gaps to the other runway at the same time, due to the dependent approaches,
Dairyground, how do you, as a radar controller, know how many seconds to provide, and how do you achieve it? Especially where the headwind component at 3000ft may be 50kts, and 10kts at the surface, or indeed vice versa? It requires considerable tool support and a change to the method of operations, which is being worked on.
Talkdownman
3rd Aug 2012, 07:09
Wouldn't it be great to click on aircraft No. 1, click on aircraft No. 2, Enter the Runway Occupancy Time Spacing of the day eg. '1 min 43 secs', upload it all to aircraft No.2, same for No. 3, same for No. 4 etc, then sit back and watch...
An alarm could activate on rollout to get the pilot to operate the tiller to taxi in...
DaveReidUK
3rd Aug 2012, 08:21
The radar minima in this case is 2nm on the diagonal. 2.5nm is usually the lowest aimed for. The issue being that from 0620 onwards when departures begin, we need a minimum of 6nm gaps to the departure runway, which only works if you provide 6nm gaps to the other runway at the same time, due to the dependent approaches.
Thanks. Yes, I understand that two parallel offset landing streams at 6nm separation, with departures in the gaps, gives the same arrival rate as 3nm separation on a single runway.
And yet segregated ops can typically see 41 or more landings per hour compared to the 38 in the 0600-0700 hour, suggesting that there's more to it than simply theoretical capacity ?