On my recent trip to London, I landed on UA 924 (a 777) in thick fog. We did not see the ground till we flared over the concrete and even then I could see very little. Looking at the fuselages of aircraft as we taxied and then at Terminal 3, I estimate vis at the field at arrival time was around 400 horizontal feet and maybe about 100 feet vertically. The approach was perfect all the way down, smooth, steady, and stable, and was an impressive affair. I can't imagine how things must have looked from the drivers' PoV.Would such a landing typically be an Autoland ?At what visibility level does a landing qualify as "blind" and what is the normal jetliner landing procedure for that ?Happy New Year !JS

The only way the plane could land in that visibility would be an autoland. And type of manual approach would have minimums above 100 feet- Which means if they get to 100 feet and cannot see the runway, they would have to go around. I think most minimums are 250 feet or greater.I'm sure others have more detailed information, but for a Category III autoland both aircraft and the runway have to be certified for it. There are different classes of category III approachs. I think in that condition it would be a IIIa?If you look at an approach chart for a particular runway, they list the minimums on there. I'm not an instrument guru so like I said others could tell you more.

For an ILS it is a Precision Approach so it has a Decision Altitude and not a Minimum Descent Altitude like for a Non-Precision Approach. A Decision Altitude is the height at which a decision must be made to go around or continue the approach. If you see any portion of the runway which includes the ALS, VASI, threshold lights, you can continue the approach if the visibility is above minimums. CAT I ILS minimums are usually 200 but are always tailored for different airports with restrictions set in the TERPS. For an MDA you can descend to that altitude but you have to hold at it (I think it is -0+100 on the checkride) until the missed approach point then you have to execute the missed approach procedures. If a normal landing can be made from the location you are in without losing sight of the landing environment and vis mins are good then you can go ahead and descend to make a landing.

I think the visibility at the time was around 600'. This would indeed mean a CAT III landing. The lowest DH for a CAT III is simply defined as less tht 50' which means a CAT III landing can be to as low as zero feet DH and 75m visibility.However, the capability to operate to CAT III not only depends on aircraft and airport capability (as Christian has identified), it also dependings on operator capability (training, SOPs, safety record, maintenance record, etc, etc) and crew training and currency.Basically, the minimum decision height for a CAT III approach could be limited by operator authorisation and crew training and currency as well as the limits defined by the airport and aircraft systems.

Chris-It is +100 -0 for the checkride. I was just informed of that because I'm prepping for my instrument checkride soon. ;)

>I think the visibility at the time was around 600'. This>would indeed mean a CAT III landing. The lowest DH for a CAT>III is simply defined as less tht 50' which means a CAT III>landing can be to as low as zero feet DH and 75m visibility.>>However, the capability to operate to CAT III not only depends>on aircraft and airport capability (as Christian has>identified), it also dependings on operator capability>(training, SOPs, safety record, maintenance record, etc, etc)>and crew training and currency.>>Basically, the minimum decision height for a CAT III approach>could be limited by operator authorisation and crew training>and currency as well as the limits defined by the airport and>aircraft systems.My question to all of you is....once they get the plane on the runway, how in the dancing bananas do you TAXI it in such conditions?!Surely, from a height of a 777 cabin, you can't see the taxiway lights/markers if its landed in CATIII conditions will full autoland?

No need for the frantic fruit. Apparently 75m visibility is the minimum safe for taxing. If it wasn't for the taxing problem such aircraft could land in zero visibility, this called CAT IIIC. I'm not sure what Heathrow's specific CAT III minima are.

There are several different ways to taxi in minimum conditions. You can follow a follow me car to the gate or there is a low vis procedures at some airports where you taxi to spots painted on the ground and hold.

I did wonder how on earth we were able to taxi anywhere after landing. You could see almost nothing at all and when we docked at the gate, you could just make out the fuselage windows of the jet at the next dock, about 200-300 feet away. Unbelievable to be able to arrive in such terrifying conditions--and so smoothly !JS

>>Unbelievable to be able to arrive in such terrifying conditions--and >>so smoothly !I believe that, in general, autoland does produce a smoother landing, but it also eats more runway. A well executed manual landing is intentionally firm.

>windows of the jet at the next dock, about 200-300 feet away. >Unbelievable to be able to arrive in such terrifying>conditions--and so smoothly !>>JSWow, talk about your stereotypical London weather! With that kind of fog, it's weather where in 1889 the newspaper criers would have shouted the headline, "The Rippa Agaiyn! The Rippa Agaiyn!"The most similar conditions to what you describe that I have landed in were at Juneau, Alaska PAJN.RhettAMD 3700+ (@2530 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 3-3-3-8, WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian

>Chris->It is +100 -0 for the checkride. I was just informed of that>because I'm prepping for my instrument checkride soon. ;)That's by far the worst part of the instrument checkride. Try holding MDA + 50 ft, because most DPEs really will fail you for going busting the MDA by even the smallest amount.

Yep it is a instant failing factor.

CYYZ, Pearson in CANADA has a low visibility taxi chart.JimCYWG