MD11 Autoland Question

[Elsmoko 5]

When autoland is properly engaged, sometimes the AP will disengage when nearing touchdown.  Not a big deal > it helps to hone

reflexes and teach flexibility ~   however, can anyone tell me what circumstances (wx conditions, etc)  cause this behavior.  My

controllers are not spiking and I've had the correct ILS freqs set in all cases.

Best to all,

Ken

 

[flyingnoob 25]

I have kind of had this issue also, maybe the same as you decribe where dual land is showing then changes to loc( or app) only and the A/P disengages at around 500ft.

I was going to post this on my own thread but seeing as it is quite sinilar i hought i would just add on to this thread.

Apologies for the hijack if the smptoms are not similar.

 

Regards
 

Edited July 10, 2013 by flyingnoob

[trollcopter33 2]

Are you sure you are landing on a runway that is CATIII capable?  If not, then you can't carry out a full autoland.  And besides, landing is the best part.  Why sit back and let the plane do it for you? B)

[pcubine 143]

Are you sure you are landing on a runway that is CATIII capable?  If not, then you can't carry out a full autoland.  And besides, landing is the best part.  Why sit back and let the plane do it for you? B)

 

If there is an ILS approach in FSX to any runway a full Autoland can be done on that runway.

 

Michael Cubine

[flyingnoob 25]

Are you sure you are landing on a runway that is CATIII capable?  If not, then you can't carry out a full autoland.  And besides, landing is the best part.  Why sit back and let the plane do it for you? B)

I don't know about cat 3 or whatever, but its happened a few times at an airport where it will flare itself one time and disengage another, - ie there is no consistency.

 

Thanks anyway

[idahosurge 2]

The CATIII requirment is for real world only, FSX and the PDMG MD11 does not care if the runway you are landing on is CATI, CATII or CATIII, as long as you have a valid ILS and G/S the plane will do a full autoland. The only time I have had this happen was at KBUR. That was because the ILS and/or the G/S at KBUR cuts off before you get down to the runway. I do not know about now, but back then it was the same way in the real world. For some reason on Rwy 8 at KBUR they wanted you to take manual control a mile out or whatever the distance was and it was setup the same way in the Navigraph data base I had at the time for the PMDG MD11.

[3-2-1-Now 126]

The only reason it will drop out of autoland (especially DUAL LAND) is due to system failure, system error, loss of signal, or out of flight parameters.

 

Check that you do not have the option for flight controls to override the autopilot, too, as this can also force a disconnect of the autopilot system, even in autoland.

 

Best regards,

Robin.

[flyingnoob 25]

Hi Robin,

 

Thanks for the heads up, although I do normally leave the controls alone till its flaring, then I hit the F2.

 

It disco's around 300-800ft, - the former being the most frequent.

[3-2-1-Now 126]

IIRC, depending on the approach type, you enter the MDA altitude into the FMS, then passing that altitude, the FMS forcibly disconnects the autopilot.

 

Are you definitely selecting the correct approach type in the FMS? ILS will NOT ask for this value.

 

Best regards,

Robin.

[flyingnoob 25]

i pretty much fly only Europe and dodge about.

 

All i can really say is for example if im going down the ils 28 @lpfr odemi2k hit FR607 @5000ft hit a right turn to establish, - it will turn onto the ils and descend fine.

 

I know VERY little about flying, but on my fms, i hit my last waypoint>star>then select ODEM2K and ils28 - hit insert then on the next page i get APPR TRANSto LPFR (in tis case GEBTI or VFA) i normally leave this alone - i guess you may say "this could be the issue" and i wont argue with that as i do not know any better, - but seeing as this is what i do ALL the time, sometimes it flares fine, and sometimes A/P disco's.

 

I hope you see where i am coming from?

 

Thanks

 

Paul

[mburkhard 23]

Ken, Paul,

 

a common mistake to cause autopilot disengagement shortly before touchdown is that the LAND mode did not engage. You will then see a APPR ONLY on the FMA. The main cause for this with the PMDG pilots in the past was they were not at landing configuration when passing 1500ft RH. It is at THAT point where LAND mode is armed, and if you are not at landing flaps (35 or 50) at that point, you will get APPR ONLY, and this will cause the AP to disconnect later on.

 

Hope this helps!

Markus

[flyingnoob 25]

_Markus,

 

_{You are a star, so basicly full flaps by 1500ft, I normally drop my gear about 1800ft, and then give it 35 flaps, so in that case I must be just lower than the 1500ft that's required.}

_{whats RH?}

 

_Regards

 

_Paul

[xxJohnxx 21]

RH = Radio Height

 

Basically the height above the ground, measured by your radio altimeter.

[flyingnoob 25]

Ah ok,

 

Thanks john/jon

[mburkhard 23]

You are a star, so basicly full flaps by 1500ft, I normally drop my gear about 1800ft, and then give it 35 flaps, so in that case I must be just lower than the 1500ft that's required.

 

Paul,

 

extending the gear at 1800ft RH is fine if you fly in CATI or better with a manual landing to follow the ILS. Just be careful to be at Vapp, gear down and landing flaps when reaching 1000ft RH.

But if you're doing a low visibility approach CAT II or III then you should slow down earlier, not just because of the AFS and its 1500ft limit for an autoland. This will also help to have more time for the important monitoring required for such an approach.

 

Cheers,

Markus