Simviation Forums

when visibility is less than 5mi, can pilots land the plane manually? or do they use AP?

There is such a thing as "autoland", but not all planes are equipped for it. Almost every time, the AP is turned off on short final, if not sooner.  Generally speaking, though, 5 miles isn't bad vis. to have on an instrument flight, considering the limit for VFR is 3 miles!!;D
 I think (offhand- not IFR-rated) that the typical limit at  airports  is more like 0.5 miles- any worse, and the airport's closed to IFR arrivals.  There's obviously a ceiling limit, too- not sure, but I'd say less than 1000 feet AGL.
  There's a minimum altitude specified at each airport (depending on terrain, etc.); if you reach that altitude on approach and don't see the runway, you must abort (following an airport-specific flight path to avoid terrain and obstacles), and either go to a holding pattern until it improves, or go to an alternate airport.

Standard CAT I (manual approach from DH): one half statute  mile or 2,400 RVR. It may be reduced to RVR 1,800 feet when centerline and touchdown zone lights are provided. Normally decision height is 200 feet above touch down zone elevation.

for CAT II (manually flown from 100' above TDZE): an RVR of not less than 1,200 feet.

Only CAT IIIc has no RVR requirement, making it the only approach flown in "blind" conditions.

........By the A/P, of course.  :-*

I'm guessing, CAT II, would be the answer to your question. "lowest flown manually"........100'AGL and less than 1/4 statute mile visiblity!   Of course, this isn't flown manually, it's just landed manually.

RVR means Runway Visual Range btw.

Question is...are Cat IIIc landings approved in commercial aviation? I know military guys do it.
But given that the runway is certified for it, could a 747-400 land legally?

I have read that the farthest you can go in commercial is Cat IIIb landings. Reason for this is not because of aircraft limitations (heck Autoland systems have been around for some 40 years or so) but due to the required visibility and hazard of taxiing in blindness.  ???

Commercial planes can do CAT III approaches quite nicely in fact. Just involves configuring the A/P a little differently and making sure you arm "Flare." The plane comes in, makes a pretty nice flare, and touches down, then your fingers flip the A/P switch (which they have been resting upon) and you throw in the necessary items (which for a CAT III approach, bad weather, probably full reverse and heavy braking). Definetly a two-pilot approach.

Commercial planes can do CAT III approaches quite nicely in fact. Just involves configuring the A/P a little differently and making sure you arm "Flare." The plane comes in, makes a pretty nice flare, and touches down, then your fingers flip the A/P switch (which they have been resting upon) and you throw in the necessary items (which for a CAT III approach, bad weather, probably full reverse and heavy braking). Definetly a two-pilot approach.

Good point made about flying some of these models on IFR approaches- they really are meant for a crew of two, and not just in case something happens to one of them... I've made one semi-realistic 747 flight so far, and there's a whole lot to do in the last ten minutes...!!

So in real life, will a pilot attempt to land in 1.2mil manually? will he disengage AP after LOC directly?

If "1.2mil" stands for 1.2 statute miles, the answer is yes.
Here's the breakdown again:

(coupled: means that aircraft is flown with the autopilot slaved to the ILS)

CAT I- can be coupled to 200' above TDZE but must be flown manually(hand flown) from DH to the ground. That would mean hand flying out of a 200' overcast with as low as ONE HALF  statute mile visibility.

Personally, I've flown CAT I's entirely by hand, from the final fix, to DH, to the ground. Trust me, this isn't macho chest beating, it was required because early autopilots could be lousy and near DH would command a "porpoising" glide path as the AP tried to recapture a glide slope.

CAT II- is coupled to 100' and as little as ONE QUARTER statute mile visibility and then hand flown to the runway.

Only the CAT I can be flown manually for the entire approach.

1.2 mile, that's easy for airline pilots to fly the entire thing by hand (referencing the ILS in the clouds/fog of course). At 1.2 mile visibility, ATC isn't clogged or anything, it's just another day for us.

Thanks

Thanks

No problem, that's what we're here for.