Shuting off the ILS

[alrot]

what is the "Legal" distance to shuting off the ils and take the control of the airplane on final aproach , for Tubes (a320,b737/747/777 etc) when is the right moment to pass to manual control ?

[EVVFCX]

Hi alrot,

I suspect the time to go off ils would be at the minimum decision height for whatever runway your approaching.

Can't think of a reason other than an aborted approach and not seeing the runway to come off ils.

regards

Syevee

[pegger]

All categories of instrument approaches have published minimums for decent altitude and visualization of the runway with respect to the speed class of the aircraft you are flying, except some autoland catagories. If you don't have the runway in sight at the minimums, then it is go-around time, and perhaps deviation of the flight to the alternate airport.

For example, a CAT3 approach at KSEA has the following:
CAT3a RVR070 (700 feet)
CAT3b RVR030 (300 feet)
CAT3c N/A (not applicable)

[reachva]

It also varies with the specific airlines operating procedures. Usually the decision height is the time to switch over to manual flight (as I do in sim) however some airlines I've heard advocate making the switch to manual earlier.

For a rule of thumb, I tend to prefer flying the last 1500ft down to the runway than letting the computers handle it, I get nervous watching the ground growing closer without my hands on the controls!

[WPadgett]

Just a guess but I believe he means "when to turn off the auto pilot" not "the ILS." The only way to "turn off the ILS" would be to change the nav frequency, a very bad idea in IMC.