I need a little clarity...What are the rules regarding landing when visibility is bad, especially regarding airliners? Can you land in even 0/0 conditions if the pilot feels he can land, or do you go strictly by the minimums published on the landing chart? Or is it the airports decision as to when they feel landing conditions are too unsafe? Thanks for your insight.

Well, the official answer is, "It depends." Generally (9 times out of 10) the pilot has to go by the minimums published on a approach plate. (typically 200 feet and half a mile, though this can change) There are situations in commercial flight (both part 135 and 121) where different minimums apply than what is written on the plate. There are also situations at some airports where due to hazards (Surrounding terrain or runway configuration, for example) the airport must close under certain weather conditions, in which case no one could land except in an emergency. This would usually be depicted on the approach plate or the minimums would account for it. Always though, the pilot is the final authority. He may never exceed the legal limits, but he may always abandon an approach if he feels conditions are unsafe.

Thanks a lot for your Rob McCoy.

You can't land if the conditions are below the minimums for the approach. Period. OK, OK ... there's wiggle room and cheats some pilots will use, but basically you can't go lower than what it says on the chart.Now, not all approaches, planes and pilots are created equal. The standard Category 1 ILS approach is usually 200' and 1/2 mile visibility. I can fly that approach to minimums in my Skylane as can a 747-400 captain.Category 2 approaches will take you lower ... usually 100' and 1/4 mile vis. To qualify for Cat 2 minimums the facilities, aircraft and the crew have to be certified to conduct the Cat 2 approach. I can get certified to conduct a Cat 2 approach in my Skylane, but it would be a lot of trouble and it wouldn't be worth it.Category 3 approaches (which are further divided into Cat 3a, 3b and 3c) are the only approaches that will get you down with a 0' ceiling ... 3a requires 750' vis, 3b 150' vis, and only Cat 3c approaches will get you to 0/0. I'd get laughed out of the office if I ever even thought of trying for Cat 3 certification in my Skylane :-lolIf you want to find out all that's required to get approval for Cat 3 landings, check out http://www2.faa.gov/avr/afs/afs410/120-28d.rtf ... it's 88 pages of oh-so-fun stuff on getting certified for Cat 3 operations :)

Just to follow up. CAT III ops are always with the autopilot. CAT I and II ops can be flown even if weather goes below minimums after the pilot has crossed the final approach fix inbound. As for CAT III if at anytime the wx falls below mins the pilot must execute a missed approach. Also if the winds exceed limits for the CAT III approach a missed must be executed.Take care, Grady Boyce

Airlines also impose their own minimums(obviously higher than the published). Many times at CYYZ, in bad weather, I've heard Air Canada aircraft land, whereas other airlines such as AA and United announce the condtions are below "the company" minimums and they request either another runway with a higher CAT, or just do a missed and head somewhere else.

USA reg's only require visiblity for landing minimums on a CAT 1 ILS, cieling doesn't matter.A FAR 121 airline pilot outside of the Final Approach Point, (glide slope intercept on a ILS}or Final Approach Fix , (non-precison app)cannot begin a approach if the reported visiblity is below the minimums of the chart. However, once a pilot is inside the Final Approach Point or Final Approach Fix, he may continue the appraoch even if the reported visiblity is below minimums. At DH he can then land if the runway enviroment is in sight or may have to go around if the visibilty is in fact below minumums and he can not see the runway enviroment. If ATC is reporting visibiliy at 0/0, then I don't know if you can start a approach. There are Cat III ILS's that permit very low visibilty landings and use a autoland feature.