CAT III minima
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hi bochos,
you're on the right track. good way to get several thruths right & wrong !
alert height has nothing to do with a kind of mode that would arm and engaged, freezing some devices ... like the land inhibit for some failures, or ILS lock below 700 ft.
it's rather a decison point (sama concept as V1 for take off) that helps the pilot in a CAT III b having a failure at very low height. if it is at or less than 100 ft height, he will disregard the failure until aircraft stopped on the runway since he knows the aircaft will be able to complete the autoland safely (except a second failure affecting automatisms just after (the first being as well in relation to autoland equipements. bad luck !) or the red autoland warning)
see you
cyrille
you're on the right track. good way to get several thruths right & wrong !
alert height has nothing to do with a kind of mode that would arm and engaged, freezing some devices ... like the land inhibit for some failures, or ILS lock below 700 ft.
it's rather a decison point (sama concept as V1 for take off) that helps the pilot in a CAT III b having a failure at very low height. if it is at or less than 100 ft height, he will disregard the failure until aircraft stopped on the runway since he knows the aircaft will be able to complete the autoland safely (except a second failure affecting automatisms just after (the first being as well in relation to autoland equipements. bad luck !) or the red autoland warning)
see you
cyrille
Join Date: Oct 2000
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I Understand things slightly more operationally in a question of certification. Maybe i'm wrong, but you live and learn.
Cat IIIa 50'/200m so on the roll out the captain can keep the aircraft on the centreline using rudder control as soon as the a/c completes the flare, autopilot has to come out, as there is no rudder control by the autopilot. If you leave it in the autopilot tries to maintain the centreline using aileron, which on the ground is useless
cat IIIb the autopilot can control the rudder and so can maintain the centreline during roll out. Hence lower minima.
cat IIIc the autopilot can complete the roll out and taxi the aircraft to the stand. (which at the moment is impossible as there is no suitable guidance systems). if it's 0/0 you can't see so you can't manually taxi.
I'm willing to be corrected, but this is how i understand the essential differences between the 3 options. I've only ever flown cat IIIa (i really don't like it btw, very unnerving).
Cat IIIa 50'/200m so on the roll out the captain can keep the aircraft on the centreline using rudder control as soon as the a/c completes the flare, autopilot has to come out, as there is no rudder control by the autopilot. If you leave it in the autopilot tries to maintain the centreline using aileron, which on the ground is useless
cat IIIb the autopilot can control the rudder and so can maintain the centreline during roll out. Hence lower minima.
cat IIIc the autopilot can complete the roll out and taxi the aircraft to the stand. (which at the moment is impossible as there is no suitable guidance systems). if it's 0/0 you can't see so you can't manually taxi.
I'm willing to be corrected, but this is how i understand the essential differences between the 3 options. I've only ever flown cat IIIa (i really don't like it btw, very unnerving).
Join Date: Nov 2008
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Dear C, saludos...
AH is applicable whenever Fail Operational is announced regardless of approach. MFGS is frozen at AH thus the Fail operational mode is safegurded by the A/c s ability to cope with any single faileyre.
When is it "armed"? Is it "armed" when dual is announced on fma or at 100ra? What happens if you have fail passive, is fmgs still frozing passing 100ra or is not? from what i understand , sigle operational is not safegurded from AH thus it should not be armed....
As 100ra is the max AH and not the minimum (i now completly understand why) then, why should opperators change it to any lower value? what extra safety could be acheived with fail operational mode? below the nominal AH fmgs is frozen, duall is safegurded, a/c is able to cope with faileure, what else is for operator to lower AH value? Am i missing nything?
I am reading the A320 GTGRIPS manual and thats why all these questions were generated.... am just half way ... am sure more will be to discuss as i read through ,
stick around
... : )
bochos
AH is applicable whenever Fail Operational is announced regardless of approach. MFGS is frozen at AH thus the Fail operational mode is safegurded by the A/c s ability to cope with any single faileyre.
When is it "armed"? Is it "armed" when dual is announced on fma or at 100ra? What happens if you have fail passive, is fmgs still frozing passing 100ra or is not? from what i understand , sigle operational is not safegurded from AH thus it should not be armed....
As 100ra is the max AH and not the minimum (i now completly understand why) then, why should opperators change it to any lower value? what extra safety could be acheived with fail operational mode? below the nominal AH fmgs is frozen, duall is safegurded, a/c is able to cope with faileure, what else is for operator to lower AH value? Am i missing nything?
I am reading the A320 GTGRIPS manual and thats why all these questions were generated.... am just half way ... am sure more will be to discuss as i read through ,
stick around
... : )bochos
