Flight cancellations through fog.
Thread Starter
Joined: Aug 2007
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From: East Anglia.
Flight cancellations through fog.
I have just read a reader comment in a newspaper...it went..'With all the blind landing facilities available, why don't they land aircraft in fog by using them?'
My immediate reaction to that was to think to myself, don't be silly, if they could operate they would.
What would a professional pilot (politely) tell that person are the reasons that passenger flights landing and take off in fog is not safe, please?
My immediate reaction to that was to think to myself, don't be silly, if they could operate they would.
What would a professional pilot (politely) tell that person are the reasons that passenger flights landing and take off in fog is not safe, please?
Paxing All Over The World
Joined: May 2001
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From: Hertfordshire, UK.
It doesn't really matter, when we bear in mind that - if they DID operate in the fog and had a prang the same person would say "Why on earth did they operate? They knew it wasn't safe."
Many people think that automation can save the human race and there are countless examples - such as the company trying to sell CCTV monitoring software that can watch pax during the flight and determine 'suspicious behaviour'.
Some humans like to think that machines are the answer but the answer is that humans need humans!
Many people think that automation can save the human race and there are countless examples - such as the company trying to sell CCTV monitoring software that can watch pax during the flight and determine 'suspicious behaviour'.
Some humans like to think that machines are the answer but the answer is that humans need humans!
Thread Starter
Joined: Aug 2007
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From: East Anglia.
After more thought, it seems to me that landing and take off could be facilitated but, it is before and after that where the problem lies. A flight crew would be moving blind seeking the runway for TO and the same for seeking the stand after landing. That bodes for multiple pile ups and is totally taboo.
Joined: Aug 2006
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From: Glasgow
Most modern aircraft have the ability to land in fog provided the crew have completed the extra training.
The problem is that ATC have to use much greater separation between landing aircraft in very low visibility so that the preceding aircraft is well clear of the runway and the Instrument Landing System transmitters before the next lands.
Really thick fog is best for the best equipped airlines as many of the lesser machines divert!
Paradoxically, once the vis improves the delays worsen as all the diverted aircraft try to get back in.
The problem is that ATC have to use much greater separation between landing aircraft in very low visibility so that the preceding aircraft is well clear of the runway and the Instrument Landing System transmitters before the next lands.
Really thick fog is best for the best equipped airlines as many of the lesser machines divert!
Paradoxically, once the vis improves the delays worsen as all the diverted aircraft try to get back in.
Last edited by scotbill; 21st November 2011 at 12:26. Reason: typo
Joined: Feb 2001
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From: UK
Current technology means that whilst many aircraft are capable of landing in even zero visibility, the radio signals needed to effect such a landing will be affected by nearby objects, such as other aircraft.
To prevent this interference aircraft needed greater than normal separation on approach, and the area around the runway must be kept clear. This means that landing rates are greatly reduced, hence delays and cancellations.
With the gradual increase in the use of mls instead of ils this problem should lessen.
To prevent this interference aircraft needed greater than normal separation on approach, and the area around the runway must be kept clear. This means that landing rates are greatly reduced, hence delays and cancellations.
With the gradual increase in the use of mls instead of ils this problem should lessen.
Joined: Aug 2000
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From: EGGW
The problem with airports like LHR and the major US airports such as AT & ORD is a/c can land using Cat 3 landing systems.
Problem is in Fog or Bad weather the separation between a/c landing is increased, so reducing the number of landing per hour.
So if your normal landing number is 50 per hour on a clear day and is reduced to 25 in bad weather, something has to give.
Hence cancellations and a/c diverted due not enough fuel for holding delays.
I remember 15 years back on a LH A320 circling over London for over an hour, kept looking out of the window and seeing the One Canada Square – Located in Canary Wharf and the Crystal Palace TV masts over and over again, poking out of the fog.
When we landed it was so thick you could only just see runway edge.
Problem is in Fog or Bad weather the separation between a/c landing is increased, so reducing the number of landing per hour.
So if your normal landing number is 50 per hour on a clear day and is reduced to 25 in bad weather, something has to give.
Hence cancellations and a/c diverted due not enough fuel for holding delays.
I remember 15 years back on a LH A320 circling over London for over an hour, kept looking out of the window and seeing the One Canada Square – Located in Canary Wharf and the Crystal Palace TV masts over and over again, poking out of the fog.
When we landed it was so thick you could only just see runway edge.
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From: The Winchester
What would a professional pilot (politely) tell that person are the reasons that passenger flights landing and take off in fog is not safe, please?
However in bad visibility the problem is often one of traffic management and flow (as was the case at London yesterday AM). Low visibility ATC procedures require (in most cases) a larger than normal spacing between aircraft flying the approach, and often more spacing between aircraft taxing in or out. The result is a reduction in the arrival rate/departure rate, prolonged airborne holding (inbound) or gate holds (outbound)....And the result of that, on an airport that operates at close to 100% capacity on a good day is that schedules are completely stuffed - at LHR yesterday start up delays were around 90 minutes at one point - that meant for a short haul flight it could have been given a start up time that was coincident with the time it was meant to be leaving it's destination to return to LHR. Once schedules are shot to that extent the airlines start cancelling services ( especially shorthaul out and back flights) in an attempt to have aircraft in position to pick up the schedule later in the day.
(edited to add: Must type faster..I agree with 'wot the last few wrote
)
Last edited by wiggy; 21st November 2011 at 11:10.
