Chicago O'Hare tower gives me orders to approach my assigned ILS runway at 5,000 feet. I try to fly auto ILS approach using the autopilot but it's acting confused. It appears to have problems lining up with the localizer and it won't descend as ordered by glideslope either. Is it because the altitude is too high? HSI is displaying localizer, glideslope and distance just fine; only the autopilot is acting weird.

Have you remembered to change the nav mode switch from GPS to NAV? If not, try that. R-

My plane doesn't have that. It's a Captain Sim 727. That plane has old-fashioned avionics and a portable GPS but no ability to couple the autopilot with the GPS in any way.

>My plane doesn't have that. It's a Captain Sim 727.Aha! Load the default C-172 and I'll bet you find its nav mode switch set to GPS. Change it to NAV, reload your CS 727, and it should be fixed. R-

Also a good rule of thumb is 300 feet for every mile to runway. So, if ORD is at 668ft above sea-level, then...5000ft (from above) - 668ft = ~4300ft / 300 = ~14 mile finalThat's a pretty long final... I like to work in round numbers, so on a ten mile final...10 miles * 300 ft = 3000ft + 668ft = ~3700ftMake sense? :)

I have to try it again but I'm onto something. The 727 autopilot has two approach modes: auto and manual. It's the automatic mode that seems to be causing problems while the manual mode follows the ILS properly.