Holding patterns -why?
The use of one runway for take off, the other for landing, has stymied the reduction in delays for years. Having had professional contact with the CAA and NATs for many years I know the "reason" but can point to many airports around the world where runways with similar proximities work in parallel for landing safely and satisfactorily.
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The fact that Heathrow operates its runways in segregated mode, with the runway roles alternating at intervals, has nothing to do with safety considerations.
Well, there is the fact that independent parallel arrival is not currently a procedure approved for LHR by the CAA
There has been no reason up to now to develop the safety case for independent parallel arrivals, given that runway alternation has been enshrined in government policy for the last 40-odd years.
But with the watered-down alternation scheme that will result if a third runway is built, simultaneous landings on adjacent runways would happen around 50% of the time and the CAA have already published their initial assessment of SOIR at LHR.
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I said I knew the reasons for the segregated mode which doesn't imply I thought it was a safety issue. The point I made about other airports was to pre-empt replies about the safety issue. Perhaps I should have put that point in a different sentence.
Staggered parallel arrivals are used from time to time. The distance between the runways is just 50 metres short of the international standard mentioned by LookingForAJob.
At SFO the distance between runway centre lines is less than 250 metres with the added complication of parallel take off on two runways cutting across the two landing runways at ninety degrees. Taking off at night towards Oakland Bay, sitting on the right hand side of an aircraft is always an interesting experience looking at two sets of lights heading towards your aircraft and being conscious of another aircraft also taking off next to you.
It would be interesting to know just how much more difficult that sort of operation is compared to slotting in take offs at LHR between parallel landings.
If and when a third runway is built at LHR it will be interesting to see just how the government of the day handles the flack that will be heading its way when parallel operations become a norm.
In the meantime, given climate changes and the increasing frequency of stronger cross winds, delays will continue and there is absolutely no prospect of a runway angled to deal with the problem.
Staggered parallel arrivals are used from time to time. The distance between the runways is just 50 metres short of the international standard mentioned by LookingForAJob.
At SFO the distance between runway centre lines is less than 250 metres with the added complication of parallel take off on two runways cutting across the two landing runways at ninety degrees. Taking off at night towards Oakland Bay, sitting on the right hand side of an aircraft is always an interesting experience looking at two sets of lights heading towards your aircraft and being conscious of another aircraft also taking off next to you.
It would be interesting to know just how much more difficult that sort of operation is compared to slotting in take offs at LHR between parallel landings.
If and when a third runway is built at LHR it will be interesting to see just how the government of the day handles the flack that will be heading its way when parallel operations become a norm.
In the meantime, given climate changes and the increasing frequency of stronger cross winds, delays will continue and there is absolutely no prospect of a runway angled to deal with the problem.
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Dave Reid,
You are conflating independent approaches with mixed mode.
They are different, one does not lead to the other.
LFAJ,
Taken in isolation, the runways are far enough apart.
However, I can see that others here know far more about this matter than I, so I shall bow out of the conversation.
Next time I'm in my office I shall pay more attention, there are obviously more people working there then I notice!
You are conflating independent approaches with mixed mode.
They are different, one does not lead to the other.
LFAJ,
Taken in isolation, the runways are far enough apart.
However, I can see that others here know far more about this matter than I, so I shall bow out of the conversation.
Next time I'm in my office I shall pay more attention, there are obviously more people working there then I notice!
IIRC, the runways are not far enough apart to comply with international standards for independent operations
"The current ICAO separation for allowing independent approaches with no mitigations is 1525m.The existing runway separation is approximately 1450m and the proposed northern runway separation is 1035m from the existing northern runway. The proposer must demonstrate that the design meets the requirements of ICAO Document 9643 The Manual on Simultaneous Parallel or Near Parallel Instrument Runways (SOIR) for all possible modes of operation, in particular given the stagger of the proposed northern runway. Appropriate mitigations will need to be provided."
You are conflating independent approaches with mixed mode.
They are different, one does not lead to the other.
They are different, one does not lead to the other.
But the proposed R3 concept of operations of necessity implies both:
a) mixed mode on one runway for the bulk of the day (because arrival and departure demand is fairly evenly balanced, except for early mornings and late evenings) with the other two operating segregated arrivals and departures
and, therefore
b) simultaneous approaches on the mixed mode runway and the arrival one, which 50% of the time will mean two adjacent runways (hence the CAA's comments above)
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I recall we trialled mixed mode once and it was an absolute nightmare for GMC, especially getting N/S departures to the correct holding point, all that head-on traffic on the outer. Went in the same bin as the tower periphery furniture and CCF 'Tunnels in the Sky'. Also better leave some room in the bin for 27RW. Do you switch off SMF when doing staggered parallels?
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Me too, pre-SMF. nats were happy at the time to turn a blind eye to it but didn't like it once their SMF was installed. Remember the fuss over the parallel Concordes? All consenting adults sensibly coordinating during an auspicious and spectacular occasion, yet those involved were seriously criticised because separation was 'lost' during parallel approaches, even with two complicit Concorde captains. Of course, the ATCO came off worst...
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I had a couple alongside each other one day, Traffic in front and behind were yellow and the two on the approach were red. The Chief Wizard asked what was going on and I said "I'm trying to find a green one for a set of traffic lights".
Some airports hold and some-Frankfurt is a good example just extend the downwind leg -before they got the extra runway that extension could be very long indeed so you could see the 'field' off to the side at about 10,000ft but probably didn't land for another 20 minutes while you went half way to Stuttgart and back . Not possible at LHR due to all the other airports and traffic but works well at Frankfurt where people were spared the going around in circles experience and don't in general realise whats going on.
Arlanda in Stockholm has situation where because of geography almost all flights arrive from the south and so rather than hold they slow everyone down over along distance and separate them in trail as the head for the turn onto finals like long drawn out queue . Singapore have their own version where you go for another trip around the island when its busy and again its less obvious the racetrack patterns. Horses for courses as they say but a lot depends on geography/traffic patterns and nearby airports or lack of.
When its extremely busy LHR (Someone will no doubt correct me if I am wrong on this) sometimes use high level or 'en route' holds where inbounds are held at points on the approach path like Southampton or one of the Lambourne inbound waypoints at say 15000 ft and above because the normal holds can get full and for ATC reasons can only operate between certain altitudes, as the stacks empty aircraft are released for these points only to pick up another hold-the normal one closer to the field.
On 'the' Sept 11 I spent 6 hours in one such hold over Lands End before returning to Gatwick from where we had originally departed-a nice sunny day and some nice scenery on part of the track but the novelty, and the view, did wear off after a while-like the first hour lol
PB
Arlanda in Stockholm has situation where because of geography almost all flights arrive from the south and so rather than hold they slow everyone down over along distance and separate them in trail as the head for the turn onto finals like long drawn out queue . Singapore have their own version where you go for another trip around the island when its busy and again its less obvious the racetrack patterns. Horses for courses as they say but a lot depends on geography/traffic patterns and nearby airports or lack of.
When its extremely busy LHR (Someone will no doubt correct me if I am wrong on this) sometimes use high level or 'en route' holds where inbounds are held at points on the approach path like Southampton or one of the Lambourne inbound waypoints at say 15000 ft and above because the normal holds can get full and for ATC reasons can only operate between certain altitudes, as the stacks empty aircraft are released for these points only to pick up another hold-the normal one closer to the field.
On 'the' Sept 11 I spent 6 hours in one such hold over Lands End before returning to Gatwick from where we had originally departed-a nice sunny day and some nice scenery on part of the track but the novelty, and the view, did wear off after a while-like the first hour lol
PB
