min vis for taxi
Join Date: May 2000
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Probably the same as the minimum visibility for takeoff or landing. After all, why taxi unless you're going from the ramp to the runway or vice-versa?
If you can't see well enough to find your way, don't taxi! While SMGCS will help in Cat II and Cat III weather, you may find that pockets of thicker fog exist, so you can't see ANYTHING! Been there; done that (in SCL a few years ago, where a fog bank was rolling in, and reached midfield when we landed; waited for a follow-me after clearing the runway).
If you can't see well enough to find your way, don't taxi! While SMGCS will help in Cat II and Cat III weather, you may find that pockets of thicker fog exist, so you can't see ANYTHING! Been there; done that (in SCL a few years ago, where a fog bank was rolling in, and reached midfield when we landed; waited for a follow-me after clearing the runway).
Join Date: Dec 2006
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OK guys
Let me rephrase the question...does that mean..an aircraft/ crew which is CAT1 certified have different TAXI visibility requirements than a CAT2 certified aircraft/crew?
surely there must be a unified value for all traffic while on ground..except for widebodies perhaps
Let me rephrase the question...does that mean..an aircraft/ crew which is CAT1 certified have different TAXI visibility requirements than a CAT2 certified aircraft/crew?
surely there must be a unified value for all traffic while on ground..except for widebodies perhaps
Join Date: Dec 2006
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OK INTRUDER....let me see if i got your last correctly.........
A normal guy in an A340-600 has better vision than another normal guy in a B727-100 simply because he's flying a newer aircraft?...
A normal guy in an A340-600 has better vision than another normal guy in a B727-100 simply because he's flying a newer aircraft?...
75 metres, in my experience, has generally been considered the min vis for taxi on A320/B737 types, this assumes centreline lighting serviceable and I think reasoning behind the 75 m is that you would be able to see at least 3 centreline lights.
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There is no min or max vis value for any aircfaft type or any pilot type. Vis is not actually measured along any taxiway anyway, the vis quoted in low vis procs is three defined points along the lenght of the runway, the touchdown zone, the runway mid point and the end of the runway. these values are constantly varying due to the nature of fog they are almost certainly not that representative of conditions else where on the airfield.
If you taxi slowly enough, using airfield charts and your magnetic compass you should almost always be able to folow taxiway lighting to a runway which will then have much brighter lighting. The danger is not seeing a less well lit object. If in doubt......stop and tell ATC.
Did hear a story of a 747 that autolanded in thick fog, and came to a stop on the runway ( the aircraft will track and stop on the centreline if full 3B) but the upperdeck was above the fog!! 10k vis from the flight deck, but still couldnt taxi!!
If you taxi slowly enough, using airfield charts and your magnetic compass you should almost always be able to folow taxiway lighting to a runway which will then have much brighter lighting. The danger is not seeing a less well lit object. If in doubt......stop and tell ATC.
Did hear a story of a 747 that autolanded in thick fog, and came to a stop on the runway ( the aircraft will track and stop on the centreline if full 3B) but the upperdeck was above the fog!! 10k vis from the flight deck, but still couldnt taxi!!
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OK INTRUDER....let me see if i got your last correctly.........
A normal guy in an A340-600 has better vision than another normal guy in a B727-100 simply because he's flying a newer aircraft?
A normal guy in an A340-600 has better vision than another normal guy in a B727-100 simply because he's flying a newer aircraft?
Either one of those airplanes/crews may or may not be Cat 2 or Cat 3 certified, and either one may or may not be operating on an airport that has operational SMGCS.
The realistic taxi minimums for either airplane/crew will depend on the certifications, airport, and current weather conditions. As I REALLY said,
There is no "unified value" for taxi visibility that I know of.
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Did hear a story of a 747 that autolanded in thick fog, and came to a stop on the runway ( the aircraft will track and stop on the centreline if full 3B) but the upperdeck was above the fog!! 10k vis from the flight deck, but still couldnt taxi!!
Happened to me in CDG eight years ago. Fine late winter early morning arrival. LVP in progress, Nr 3 for approach CAT III B no DH. RVR 100/90/110; sky obscured. First 74 for that day. When the wheels touched down, we were still VMC on top, and when the nose wheel hit the floor, we were skipping the "cloud tops" from the flight deck. Though we were light (Pax flight 75% full) I switched the autobrakes from 3 to max.....just in case. When stopped, we had no clue of the aircraft position on the runway, but TWR had perfect visual on our big top. The worst feeling was when towed from that position to the gate.
Happened to me in CDG eight years ago. Fine late winter early morning arrival. LVP in progress, Nr 3 for approach CAT III B no DH. RVR 100/90/110; sky obscured. First 74 for that day. When the wheels touched down, we were still VMC on top, and when the nose wheel hit the floor, we were skipping the "cloud tops" from the flight deck. Though we were light (Pax flight 75% full) I switched the autobrakes from 3 to max.....just in case. When stopped, we had no clue of the aircraft position on the runway, but TWR had perfect visual on our big top. The worst feeling was when towed from that position to the gate.
