Single CH

[miroslavmurin 0]

Hello,

 

What is difference between yellow and green Single CH? I saw green Single CH on some video but I can not get it during landing. I have always yellow one.

[downscc 1,327]

Miroslav, it only took me 30 sec to find the answer in the FCOM using the Adobe Reader search feature (CTRL+F):  Pg 4.10.26

[Guest]

Hi Miroslav.

 

The 737-800 Autoflight Director System is designed to provide guidance for either single or dual autopilot precision approaches (ILS)

 

If you fly a precision approach with both autopilots engaged Single CH is annunciated upon Localiser Capture (Having armed APP not VOR/LOC). After Glideslope capture and passing 1500ft RA the SINGLE CH annunciation extinguishes and FLARE armed is annunciated in preparation for an automatic landing.

 

If you fly a precision approach with just one autopilot engaged Single CH is annunciated for the entire approach after Localiser capture (you need to disconnect the autopilot at some point and land the thing!)

 

With regards to the green or amber single CH this is dependent which A/P system is installed, whether the aircraft is fail-passive/fail-operational and is often operator specific.

 

For example my operator is fail passive. Flying a dual A/P approach single CH annunciates until 1500ft RA and if a failure occurred to one of the A/P's  the other would disconnect with minimal aircraft manoeuvring.

 

737's fitted with fail operational systems have electrically operated rudder actuators which provide additional alignment and rollout capability not present in fail passive aircraft and the redundancy that a 3rd Autopilot would normally provide.

 

Hope this helped.

 

Sam Breese.

[rsvit 16]

Sam is misleaded here.

 

Yellow means that ILS beam has been captured and green one means that integrated approach navigation is used.

 

IAN means that final approach course and glide path (both of them are calculated by FMC according to the RWXX and previous waypoint crossing altitude and position data which are shown on displays as an ILS interface) or just glide path. In this case autopilot will disconnect at 100'.

 

IAN is an operator option.

[downscc 1,327]

Bingo, Rostyslav expanded the information found in the FCOM on the page I referenced.

 

By the way Rostyslav, full names in the PMDG forums please.

[miroslavmurin 0]

Thank you for information

[Guest]

Sam is misleaded here.

 

Yellow means that ILS beam has been captured and green one means that integrated approach navigation is used.

 

IAN means that final approach course and glide path (both of them are calculated by FMC according to the RWXX and previous waypoint crossing altitude and position data which are shown on displays as an ILS interface) or just glide path. In this case autopilot will disconnect at 100'.

 

IAN is an operator option.

 

Sorry if I caused any confusion Rostyslav. As I said, my operator's fleet is fail-passive and I'm unfamiliar with IAN (We can only fly to CATIIIA minima). I'm not familiar with the PMDG's FCOM's only my operators!

 

Regards.

 

Sam Breese.

[miroslavmurin 0]

It is confusing because when I land in Insbruck runway 26, I have sometimes green Single CH and sometimes yellow Single CH.

[badderjet 181]

As stated above, it depends on whether you fly the ILS or you fly an NPA with IAN. ILS will trigger a yellow SINGLE CH while IAN will give you a green indication. That's it. I can only imagine it's green for IAN because it's the "normal" status, there is nothing better (like dual channel in case of an ILS).