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dick seiders

Well Known Member
Went flying on last Sat. and checked out my AP system again. It's a nice option for kicking back and relaxing while in the sky. Works great. So I decided to use the AP to fly a simulated gps approach on the way back to the home airport and all went well till about 3 miles out where the AP got confused and started hunting the nose and became just generally unhappy. Not wanting to harm the AP I shut it off. Now I know the 496 is not app. certified, but didn't really expect it to get confused until over the runway. Has anyone else experienced this at 3-4 miles out, or am I the only idiot who tried it?
Dick Seiders
 
The AP in your setup would not know where it was in relation to distance from the airport. The 496 does not output CDI scaling information so the sensitivity of the HSI needle that the AP is trying to center won't change either. This has to be done manually.

The 496 will simply provide the AP with a course and cross track error value that the AP is trying to reduce to zero. Once you cross the threshold in the stripped down approach in the 496, if you did nothing, the AP should just continue flying straight down that course forever unless you do something.

Bottom line is that the distance to the airport will not impact what you experienced.

Either the AP wigged out or the 496 did and the AP was trying to follow incorrect information.
 
On several occasions mine has gotten confused when "locking on" in NAV mode. It made the usual turns while intercepting the magenta line, but never acquired the heading. I shut the unit off and started over and the unit worked fine. Truthfully, it is not the best unit I have ever used, but not the worst either. It still looses the nav signal on a regular basis. I like Dynon and their products, but they need to address this and I think they have had ample time.
 
If you set your AP decent rate for roughly 300/500 fpm and change your altitude to the airfield elevation when you hit 400ft on your 496 vertical decent rate, your "nav/alt buttons" will bring you much closer than you think. Not safe enough to try a real approach but certainly a nice way to descend to pattern altitude
 
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