course washout in relation to autopilot

[downwind]

Dear all,

What does the term course washout mean in regards to an autopilot?? ps I have looked in ac electric books for the explanantion!

thank you. dw.

[hetfield]

Hi,

course washout function on AP/FD is used to follow LOC in x-wind.
e.g. over a period of time (100s ?) the AP/FD takes the new heading as datum and if the course error is zero, it's washed out. You can proof it if you follow the LOC on a beautifull day and turn the ILS course in the CDI for some degree! The deviation remains (zero I hope ;)) but nevertheless your AP/FD will interpret it as a wind change, starts turning but will come back.

DON'T DO IT FOR AUTOLAND.
That's a different story.

regards

[happybiker]

try this link which also covers the subject
http://www.pprune.org/tech-log/352043-crs-selectors-b737-800-a.html