HI

I've programed the FMC thro' the CDU on my 737 Pilot in Command (a simplied programming version from the manual) and am trying for an ILS approach with the Autopilot.  With one of the autopilots is armed, and when the glide slope and localizer deviation indicators appear on the EADI, I select Approach on the MCP and select the second autopilot.  Both autopilots should now be armed but I find that the first autopilot disarms.  How can I prevent this happening?

Sounds correct. Near the airport, I click the VOR LOC on,

then as it turns towards the runway, I immediately click APP Hold

on.  Don't click either of the autopilot buttons. Otherwise it will

not work.

Cheers

Peter  Sydney  Australia

I don't have any of the Pilot in Command airliners, but I note that with the PMDG and Quality Wings Boeing products, selecting Approach on the autopilot automatically activates all the autopilots and LAND appears on the MFD. 

Bill

The little manual states that to fly an ILS approach with autoland SIMPLIFIED VERSION (the first autopilot having been enable for the flight) and when the glide slope and localizer deviation indicators appear on the EADI, then

step1: select APP on the MCP and then

step2: arm the remaining autopilot

It clearly states to ensure BOTH autopilots are armed.

As I say above, when I arm the second autolilot, the first autopilot disarms.

You definitely need to have multiple autopilots engaged for autoland and I wonder if what you are encountering is a glitch in the Pilot in Command version. It might be worth waiting until you are established on the centreline and glide slope before activating the second autopilot and see if that makes any difference although I'm not sure that it will. 

Bill 

Please can I explain further. 

I do always see the two little red deviation indicators, one to the left and one below the EADI when approaching the destination airport.  I then approach the localizer at approximately 30 degrees for a clean interception.  When near the localizer I expect to see the left hand red deviator changing to a red left pointing arrow and two green rectangular boxes appearing at the bottom of the EADI to indicate the localizer is engaged. I don't always get these green rectangular boxes.  If I do, then when the green boxes start to move, at this point I select APP and arm the second autopilot.  The first autopilot shouild remain armed but it does not.  This is my situation.

26 minutes ago, twister1853 said:

The first autopilot shouild remain armed but it does not.  This is my situation.

Then you have not captured the glideslope yet.  Here's another related topic -

For me, it is kind of difficult to see what's happening in your situation without being there in your cockpit as you are trying to land.  Personally I only use the APP and not the loc.  I thought 'cat' and scianoir had the perfect response but it was not.  I suspect there is no answer.

Thanks to all for the replies.  It has worked in the past: it's the randomness that's irritating.

 

The Just Flight forum is often good for these kinds

of problems. Try the General Discussion Forum.

Cheers,

Peter  Sydney  Australia