Back course

[Kristian17]

What are the procedures for using the back course switch on the autopilot panel?

Can you fly a back course app. at any airport with an ILS on one side of the rwy? Are there airports where a back course approach is mandatory?

Thanks for the help

Kristian

[Intruder]

What airplane? What does the book say?

In the 747 Classic, the BC switch only coordinates the sensing of the FD on a LOC BC approach so it behaves like it would otherwise.

Why would you think you would use it other than on a BC approach? If you don't understand the system, don't fly it!
:mad:

[westhawk]

K,

The BC switch or push button/annunciator installed in many aircraft reverses the CDI needle sensitivity in order to facilitate the execution of a LOC BC instrument approach procedure. Localizer back courses are used only when executing a published instrument procedure. The specific procedures to set up the NAV display, FD or autopilot modes for a BC approach will be specific to the particular aircraft used. The jets I fly do not have a BC function switch. Reverse sensing is accomplished by setting the front course on the HSI course selector. This doesn't work the same way on a VOR head with OBS so a switching system to reverse the needle sensitivity was required in order to give a "normal" indication while inbound on a back course. Some transport aircraft with HSIs had them too so that crews could just set the inbound course without worrying about the reciprocal course. If you find this confusing, then my work is done! Try doing a WWW search for "localizer back course". I'm certain you'll find plenty to add to the confusion. Enjoy.

Best regards,

Westhawk

[low n' slow]

Hi!
As far as I know, there are no approved backcourse approaches in JAA countries. I know you didn't specify it, but that's my reference. I believe though, that there are some approaches that use it in the states.
Shooting such an approach should be similar to an ordinary LOC approach. Remeber though that it has to be published to be approved for you to do it, even though you might pick up a signal here and there...
/LnS

[enicalyth]

Nope. Mandatory never. Can't do it in a 744.

[Kristian17]

Thanks for your help!

Kristian

[Intruder]

Nope. Mandatory never. Can't do it in a 744.
Not a universal truth; maybe it varies with local certifications...

Our 744s can do back course approaches. Just can't do them in Approach mode -- use LNAV instead.

[westhawk]

I believe though, that there are some approaches that use it in the states.

L'nS,

Correct! It was a cheaper way to provide an approach procedure to a runway served by an ILS approach from the opposite direction since it requires no additional ground facilities be funded. There are only a few of these procedures left in the US Jepp books. At one airport I frequent, KMRY, they used to have a BC, but have since installed another antenna array and commissioned a normal LOC approach in it's place. I understand they have a switch in the tower to select the transmitter back and forth between the 28L LOC and the 10R ILS as needed. 28 is the preferred runway. The ILS is only in use when weather conditions require it, which is often enough at this coastal fog-proned airport. At KASE, they use a LOC BC to define the missed approach and departure procedure course. But this is flown outbound with normal needle sensing. Because of high terrain, both of these airports would be bad places to get confused about which direction to turn to track the course centerline. I wonder how often this has been a factor in CFIT accidents.

Best regards,

Westhawk