Landing in fog
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Landing in fog
Hi People,
Quick question for you:
*Can * all commercial pilots land in fog? I know military can and do. I guess you are all IR rated like militaries are so you *could* but generally don't due to safety reasons...
So what is the visibility threshold, or does it vary due to the technical specs of the various airports??
Thanks for any help..
Quick question for you:
*Can * all commercial pilots land in fog? I know military can and do. I guess you are all IR rated like militaries are so you *could* but generally don't due to safety reasons...
So what is the visibility threshold, or does it vary due to the technical specs of the various airports??
Thanks for any help..
Yes, we can land in fog, provided that (There's always the small print, isn't there?) :
1. The pilots hold an Instrument Rating (IR)
2. The Ground equipment is suitable, e.g: Instrument Landing System (ILS)
3. The aircraft is ILS equipped.
Category 1. For a manual or automatic landing we require a Runway Visual Range (RVR) - that's visibility along the runway - of 550 metres and must see the touchdown area by a Decision Height of 200 feet.
To go below that we must have autoland fitted.
Cat 2. RVR 350m DH 100ft
Cat 3a. RVR 200m DH 50ft
Cat 3b. RVR 125m DH 15ft
Cat 3c. RVR 75m No DH (As long as the equipment monitors do not pick up a defect we let the aircraft land.)
Military pilots are no better trained for low visibility landing than civil (except for special ops using vision enhancing devices)
We don't avoid landing in fog for safety reasons - with the right kit and training for both pilots and air traffic controllers it's very safe - it's the taxying around in 75m that's difficult
Yes, from the foregoing you can see that limits vary according to the level of equipment fitted at the airport and on the aircraft; also if, for instance, any one pilot or flight engineer has not yet completed the low vis ops part of his training on type then the whole crew/aircraft/airport combination will be limited to Cat 1. Undulating terrain close to the approach end of the runway may also affect limits. Some airports have an artificial 'radar floor' of reflectors to give the Radio Altimeter an accurate datum.
Pedant notes
Some airlines have had Cat 2 manual landing using Head Up Displays (HUD).
There may be slight variations to the above figures from airport to airport.
So, what happened to the FR421 STN-PIK last night???
1. The pilots hold an Instrument Rating (IR)
2. The Ground equipment is suitable, e.g: Instrument Landing System (ILS)
3. The aircraft is ILS equipped.
Category 1. For a manual or automatic landing we require a Runway Visual Range (RVR) - that's visibility along the runway - of 550 metres and must see the touchdown area by a Decision Height of 200 feet.
To go below that we must have autoland fitted.
Cat 2. RVR 350m DH 100ft
Cat 3a. RVR 200m DH 50ft
Cat 3b. RVR 125m DH 15ft
Cat 3c. RVR 75m No DH (As long as the equipment monitors do not pick up a defect we let the aircraft land.)
Military pilots are no better trained for low visibility landing than civil (except for special ops using vision enhancing devices)
We don't avoid landing in fog for safety reasons - with the right kit and training for both pilots and air traffic controllers it's very safe - it's the taxying around in 75m that's difficult
Yes, from the foregoing you can see that limits vary according to the level of equipment fitted at the airport and on the aircraft; also if, for instance, any one pilot or flight engineer has not yet completed the low vis ops part of his training on type then the whole crew/aircraft/airport combination will be limited to Cat 1. Undulating terrain close to the approach end of the runway may also affect limits. Some airports have an artificial 'radar floor' of reflectors to give the Radio Altimeter an accurate datum.
Pedant notes
Some airlines have had Cat 2 manual landing using Head Up Displays (HUD).
There may be slight variations to the above figures from airport to airport.
So, what happened to the FR421 STN-PIK last night???
<<CATII manual-land without a HUD>>
Ooh er!
- although young Basil allegedly did something like that in an Aztec just after leaving the mil and before he'd worked out that the vis limit now actually constituted an approach ban - duh!
Ooh er!
- although young Basil allegedly did something like that in an Aztec just after leaving the mil and before he'd worked out that the vis limit now actually constituted an approach ban - duh!
Last edited by Basil; 20th Nov 2002 at 09:52.
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And there's more !
Just when you thought it was easy - if the aircraft is not fitted with an auto-rollout system (i.e. to keep it on the centreline automatically after touchdown) such as most DC-10s, the CAT IIIc vis. now requires both mid and stop-end points to have 75m RVR as well.
Previously, you only needed to consider the touch-down zone visibility (runways are divided for visibility measuring purposes into 3 zones - touchdown, mid and stop) but now these other factors come into play.
Basil is absolutely right - it's nothing to do with safety, although low-vis/fog operations are complex, especially if you develop a failure of one system or another (or an engine !) at some point in the approach. That's why we go through it again and again and again and bloody again in the simulator - I suspect most companies have similar training regimes to mine, and I do 10 to 15 practices with all sorts of nasty problems in the sim every 6 months, and quite a few for real on-line.
Basil also forgot to add 'allegedly' to his previous post, so I shall add it for you
Just when you thought it was easy - if the aircraft is not fitted with an auto-rollout system (i.e. to keep it on the centreline automatically after touchdown) such as most DC-10s, the CAT IIIc vis. now requires both mid and stop-end points to have 75m RVR as well.
Previously, you only needed to consider the touch-down zone visibility (runways are divided for visibility measuring purposes into 3 zones - touchdown, mid and stop) but now these other factors come into play.
Basil is absolutely right - it's nothing to do with safety, although low-vis/fog operations are complex, especially if you develop a failure of one system or another (or an engine !) at some point in the approach. That's why we go through it again and again and again and bloody again in the simulator - I suspect most companies have similar training regimes to mine, and I do 10 to 15 practices with all sorts of nasty problems in the sim every 6 months, and quite a few for real on-line.
Basil also forgot to add 'allegedly' to his previous post, so I shall add it for you
El D - Muchas gracias 4 legal advice. You're retained as my brief
BIK - Just shows I don't know everything but I did mention HUDs
Cat 3 man land!
BIK - Just shows I don't know everything but I did mention HUDs
Cat 3 man land!
Last edited by Jetdriver; 20th Nov 2002 at 23:23.
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Just as a point of discussion
I left the military several years ago and, at that time, the vast majority of mil aircraft (maybe all - but I can't 100% sure ) were Cat 1 only. Even the 550m viz limit was raised to 600m for all types.
When the RAF got their first Tristars from BA, the aircraft were Cat 3 capable but I believe the RAF did not train the pilots or maintain the aircraft to keep Cat 3 certification.
I am not sure of the current situation regarding the RAF and Cat 3.
I left the military several years ago and, at that time, the vast majority of mil aircraft (maybe all - but I can't 100% sure ) were Cat 1 only. Even the 550m viz limit was raised to 600m for all types.
When the RAF got their first Tristars from BA, the aircraft were Cat 3 capable but I believe the RAF did not train the pilots or maintain the aircraft to keep Cat 3 certification.
I am not sure of the current situation regarding the RAF and Cat 3.
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Dummyrun,
Re-reading my post, it's badly worded. I don't *know* that they do but am under the impression this happens from chatting to close friends who are RN pilots.
I'll happily accept what you guys say on this one - you're the experts. Me, I fix big computers.
The situation that prompted my question was thus: I was flying into Stansted (Ryanair from Biarritz) on Monday evening and was diverted to Bournemouth
"due to adverse weather conditions" which later turned out to be fog.. Rumour flying around that the pilot wasn't qualified to land in fog and some people were a bit miffed that Ryan Air were using under qualified pilots. I realise this is chinese whispers (and likely rubbish) and should be treated as such but it got me thinking about how you define fog and whether indeed *any*of you guys land in fog and why/why not.
My curiosity is now satiated - thanks. Keep up the good work.
Jim..
PS Where does a 737-800 fit in to this matrix of ILS??
Re-reading my post, it's badly worded. I don't *know* that they do but am under the impression this happens from chatting to close friends who are RN pilots.
I'll happily accept what you guys say on this one - you're the experts. Me, I fix big computers.
The situation that prompted my question was thus: I was flying into Stansted (Ryanair from Biarritz) on Monday evening and was diverted to Bournemouth
"due to adverse weather conditions" which later turned out to be fog.. Rumour flying around that the pilot wasn't qualified to land in fog and some people were a bit miffed that Ryan Air were using under qualified pilots. I realise this is chinese whispers (and likely rubbish) and should be treated as such but it got me thinking about how you define fog and whether indeed *any*of you guys land in fog and why/why not.My curiosity is now satiated - thanks. Keep up the good work.
Jim..
PS Where does a 737-800 fit in to this matrix of ILS??
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I'm sure it was rubbish ! How on earth would the rest of the passengers know if the crew were signed-off or not ?!
I think Ryanair's 737s are CAT II and it may have been the conditions at Stansted were worse than that or the aircraft may have been carrying a defect that rendered it CAT I. Or... the ILS at Stansted had been downgraded, the localiser might have failed, the approach lighting might have been out... who knows !
How do you define fog..... I used to know this... it's to do with the size of the water droplets suspended in the air believe it or not ! At some diameter of droplet mist becomes fog... or is it the other way round. Ahhh... meteorology. Purely a definition, and the real-world application is how far you can see in a straight line through it.
I think Ryanair's 737s are CAT II and it may have been the conditions at Stansted were worse than that or the aircraft may have been carrying a defect that rendered it CAT I. Or... the ILS at Stansted had been downgraded, the localiser might have failed, the approach lighting might have been out... who knows !
How do you define fog..... I used to know this... it's to do with the size of the water droplets suspended in the air believe it or not ! At some diameter of droplet mist becomes fog... or is it the other way round. Ahhh... meteorology. Purely a definition, and the real-world application is how far you can see in a straight line through it.
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<<When the RAF got their first Tristars from BA, the aircraft were Cat 3 capable but I believe the RAF did not train the pilots or maintain the aircraft to keep Cat 3 certification.
I am not sure of the current situation regarding the RAF and Cat 3.>>
Many, many years ago at Heathrow we were severely clamped out one evening with no civil traffic flying - before the days of CAT III. An RAF VC-10 had flown in a VIP earlier in the day and called for start-up to return to his base (Brize I think). RVR was about 50m so I asked him what was his minima for take off. He rather sniffily said: "I don't have a minima"... taxied out and took off! Nothing else moved the rest of that day/night.
I am not sure of the current situation regarding the RAF and Cat 3.>>
Many, many years ago at Heathrow we were severely clamped out one evening with no civil traffic flying - before the days of CAT III. An RAF VC-10 had flown in a VIP earlier in the day and called for start-up to return to his base (Brize I think). RVR was about 50m so I asked him what was his minima for take off. He rather sniffily said: "I don't have a minima"... taxied out and took off! Nothing else moved the rest of that day/night.
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Heathrow Director
It's True. When I was in the RAF many moons ago there was no prescribed minima for departure. If you could find the runway you were expected to go. We used to take off "under the hood" in training and it was a requirement to be able to demonstrate this for a "Green" or "master Green" instrument rating.
It's True. When I was in the RAF many moons ago there was no prescribed minima for departure. If you could find the runway you were expected to go. We used to take off "under the hood" in training and it was a requirement to be able to demonstrate this for a "Green" or "master Green" instrument rating.
still learning....
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BJ96-
It may also have to do with the rules for that particular pilot. In some states, you have to have a prescribed number os hours, either in the PIC position and/or hours in that type to go to the lowest minimums. He might have been the world's best, but until he had 100 hours in type, he might be classified as "High Minimums" and not be legal to shoot the approach.
It may also have to do with the rules for that particular pilot. In some states, you have to have a prescribed number os hours, either in the PIC position and/or hours in that type to go to the lowest minimums. He might have been the world's best, but until he had 100 hours in type, he might be classified as "High Minimums" and not be legal to shoot the approach.
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When I was in the RAF the only requirement for take off was 'sufficient visibility to keep straight on the runway'.
I can't remember whether it was written down as a rule, but the guidline was 6 runway lights.
The absolute landing minima were 200' and 600m - no exceptions (except in a war when the rule book went out of the window!!!!!!!!!)
I can't remember whether it was written down as a rule, but the guidline was 6 runway lights.
The absolute landing minima were 200' and 600m - no exceptions (except in a war when the rule book went out of the window!!!!!!!!!)
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The snag with barreling down the runway in extremely low vis is the dreaded RTO at or near V1.
It's ok for the aircraft with virtually centre-line thrust (e.g. VC-10 or pretty much any fast-jet), but once you're talking about aircraft with pods on the wings... well.... it would take a crew with bigger beachballs than I've got !
Almost guaranteed to come hurtling off the side of the runway. Erk. But back then men were men and guys used to fly Canberras home at the weekend
Sometimes a tricky consideration - do you de-rate and spend longer on the runway, or ramp up the thrust and have a bigger assymetric problem if one does die on you...
It's ok for the aircraft with virtually centre-line thrust (e.g. VC-10 or pretty much any fast-jet), but once you're talking about aircraft with pods on the wings... well.... it would take a crew with bigger beachballs than I've got !
Almost guaranteed to come hurtling off the side of the runway. Erk. But back then men were men and guys used to fly Canberras home at the weekend
Sometimes a tricky consideration - do you de-rate and spend longer on the runway, or ramp up the thrust and have a bigger assymetric problem if one does die on you...
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Cat 3b. RVR 125m DH 15ft
Surely, you can't possibly decide to go-around, then actually go-around without losing 15ft? Correct me if I'm wrong (often the case!).
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Remeber a DH is not a 'No Go below ht'. It is the height you make the decision at.
El Deperado
I have a couple of thousand hours on the dear old Canberra. I still have thigh muscles the size of tree trunks!!!!!! (nothing to do with my diet).
Remeber a DH is not a 'No Go below ht'. It is the height you make the decision at.
El Deperado
I have a couple of thousand hours on the dear old Canberra. I still have thigh muscles the size of tree trunks!!!!!! (nothing to do with my diet).