Autoland 3

[Tobias Wilcox 1]

When performing an ILS approach (app selected) but with only Autopilot cmd left in use, it changes to Autoland 3 once the localizer and glide slope are captured. Then obviously CMD C and R illuminate. It's not my wish to use autoland every time, is their a setting I have missed that stops this from happening? 

[scandinavian13 5,192]

1 hour ago, Tobias Wilcox said:

When performing an ILS approach (app selected) but with only Autopilot cmd left in use, it changes to Autoland 3 once the localizer and glide slope are captured. Then obviously CMD C and R illuminate. It's not my wish to use autoland every time, is their a setting I have missed that stops this from happening? 

Turning off the autopilot.

[Tobias Wilcox 1]

Does that mean you if you don't turn AP off once its captured the GS/LOC it assumes you want to autoland? Usually you only need select cmd left and it should fly in and stay that way? Autoland I thought, was an option you had to specifically select, usually in poor visibility assuming the airport supports it and your equipment.

[scandinavian13 5,192]

29 minutes ago, Tobias Wilcox said:

Does that mean you if you don't turn AP off once its captured the GS/LOC it assumes you want to autoland? Usually you only need select cmd left and it should fly in and stay that way? Autoland I thought, was an option you had to specifically select, usually in poor visibility assuming the airport supports it and your equipment.

I'm not entirely sure what your end goal is, here. The plane, if you leave the automation on, is going to assume the worst. Not sure why you wouldn't want it to.

To be honest, you're hyperfocusing on something that is entirely superfluous. If you're going to manually land the plane - it really doesn't matter if it's in simple APP mode, LAND 3, or if it goes plaid - all you should care about is that the plane got you closer to the runway. If it passed the redundancy checks, and happened to assume it's landing for you, it really doesn't matter (and shouldn't matter to you).

 

Also: welcome to the forum. Please note that full names are required to be placed in your posts (I'm assuming your user name is your actual name, but the requirement is the body of the post or auto-signature block, for consistency for the mods).

[Headley 26]

49 minutes ago, Tobias Wilcox said:

Does that mean you if you don't turn AP off once its captured the GS/LOC it assumes you want to autoland? Usually you only need select cmd left and it should fly in and stay that way? Autoland I thought, was an option you had to specifically select, usually in poor visibility assuming the airport supports it and your equipment.

Maybe you are confusing with the B737NGX, where your explanation is then correct ... 

[Tobias Wilcox 1]

Thank you for the explanation. I can see the benefits of it assuming autoland 3, safer option. It doesn't mean one has to use it, just disconnect AP prior to landing, as you would with only cmd Left in use. 

 

Tobias Wilcox 

 

[icaruss 18]

6 hours ago, Tobias Wilcox said:

Does that mean you if you don't turn AP off once its captured the GS/LOC it assumes you want to autoland? Usually you only need select cmd left and it should fly in and stay that way? Autoland I thought, was an option you had to specifically select, usually in poor visibility assuming the airport supports it and your equipment.

I get what you’re asking.  Yes, most of the autopilot-to-flight director commands are selected by the pilot.  However this level of automation, in this specific aircraft will automatically engage if the logic constraints are satisfied (without any pilot action subsequent to LOC/GS activation by the pilot) It’s not the airplane assumes the worse, since Autoland can be used in any kind of weather, it’s just a level of automation available for this aircraft, to be used if the pilot decides to.

[fleng200 6]

On the classic 747 you had to select LAND3 (or Dual if you had only 2 ap’s) before selecting the other ap’s to CMD.  Those were the days you could make a single ap approach but had to disengage them before landing.

On the 747-400 it is always all ap’s on during approach.

[berts 97]

On 11/18/2017 at 6:46 PM, fleng200 said:

On the classic 747 you had to select LAND3 (or Dual if you had only 2 ap’s) before selecting the other ap’s to CMD.

Not so.  There are no LAND3 or LAND2 switches as such on the B744 Classic. 

On the B747 Classic a minimum of two A/P's are needed to perform an autoland.  Assuming three autopilots are available, only the first A/P switch engaged to Command will fly the aircraft until it reaches approx 1,500ft agl on the ILS G/S..  The autoland system then performs an integrity check (Platt test) and any defective A/P will drop out.  The electrics split, the rudder channel engages and LAND3 (or LAND2) will be annunciated, but if not and the weather is below CAT1 then a Go-around should be flown.  From this point onwards the A/P with the least error signal will be controlling the aircraft and switching will take place between all three autopilots without any obvious indications to the crew (unless of course something goes wrong).

Bertie Goddard 

[fleng200 6]

Although I have over 9000 hrs on the classic, you should never try remember something from memory stowed away long time...

You have to switch the Nav Transfer Selector to MULTI and not LAND3 or DUAL (which will happen automatically if the Nav Mode Selector is moved to ILS or LAND).

Then you can select additional autopilots in CMD.

And from there on, Bertie is correct.

[berts 97]

On 11/22/2017 at 6:21 PM, fleng200 said:

You have to switch the Nav Transfer Selector to MULTI and not LAND3 or DUAL (which will happen automatically if the Nav Mode Selector is moved to ILS or LAND).

Then you can select additional autopilots in CMD.

And from there on, Bertie is correct.

René, 

Thanks for the compliment, but unless your B747 Classic A/P panels were labelled differently to mine then I believe you actually mean the Course Transfer Switch (CTS), don't you?  I'm concerned we are drifting off discussing the question about B744 autolands and onto details of the Classic operation here, but for what its worth I agree with you! 

On the Classic the CTS will move automatically to Multi when LAND is selected on the Navigation Mode Switch (NMS).  However, this can also occur earlier during the approach, because it also happens automatically when ILS is selected on the NMS.   Fortunately, it is relatively rare in a normal flight to have to select the CTS switch away from the MULTI position to the No.1 or No.2 positions, even during single A/P operation (i.e. with the NMS in NAV, HDG or VOR/LOC).  This is primarily because of the inherent danger of feeding all three Autopilot/Flight Director computers from the same VHF NAV Radio source and the inevitable reduction in normal crew monitoring capability this could bring about.  With the CTS in the MULTI position all three Autopilot/Flight Director computers will usually be fed from their own independent VHF NAV Radio source; (i.e. A AP/FD computer is referenced to No.1 VHF NAV Radio and so on).  On the Classic it was important for crews to know that the No.1 VHF NAV Radio controls the tuning of the No.3 NAV Radio and, athough the C AP/FD computer is normally referenced to No.3 VHF NAV Radio when the No.3 ILS is tuned, it can also be referenced to the Capt's No.1 VHF NAV Radio if the No.3 ILS fails for any reason.    

So in answer to Tobias's original question about the B744, the best way to stop the other two autopilots engaging on an ILS approach is:-

a) Use a single Autopilot/Flight Director in HDG and V/S modes and control the aircraft following the ILS raw data; ideally with APP selected and using the expanded ILS display on the ND until Minimums or visual, or:-

b) Disconnect the A/P and fly the ILS approach manually with or without the Flight Director. 

Incidentally, on the Classic it is possible to fly an ILS approach coupled to a single autopilot (e.g. where one of only two drops out (Fail Passive) if you don't understand the system properly or are daft enough to try it; but the end result will usually be very embarrassing because the aircraft will not flare!  The 744 operation is much safer because it will always engage the other serviceable autopilots for a coupled ILS approach.  This approach (excuse the pun!) also reduces the risk of the aircraft flying close to the ground with only one operational autopilot which just might happen to be the one with a large error signal.

Happy Thanksgiving

Bertie

  

       

[fleng200 6]

In my books it is called the Nav Transfer Selector (this time I looked in the manual :-)). But what's in a name.