How far into the approach with an autopilot

[Larry in TN]

Something I flew had that feature. Can't recall whether it was the 767 or 1011.

It wasn't the 767. The sim instructors were always prompting us to "brick your ship!".

The CRJ has a push-to-sync. I think I've seen it on the E145/175, too.

I've never flown it, but I think the Airbus takes the heading bug away when in (L)NAV then brings it back synced when you select the heading mode.

 

[flyingron]

I've got a 55X, if I'm flying a coupled approach, I'll fly it until I break out. If I go missed, I'll manually start the climb, but the AP/GPS can handle tracking the lateral guidance for the missed just fine.

 

[Fearless Tower]

trying to understand why the plane would be out of trim running on AP? if you are descending at known power, you are already on a stabilized approach, trimmed, no different than hand flying at that power setting and manually trimming for that airspeed.

In many GA airplanes with no auto throttles, the A/P is hunting glide slope with pitch alone. On most instrument approaches in the soup, you are maintaining your approach speed until you break out or get to DH. So when you arrive at DH and want to start slowing down to land, you may find that you have a lot of nose down trim to overcome. Just adds to the workload if you wait until DH to kick it off. Bottom line, know your airplane and account for it if necessary.

 

[flyingron]

In many GA airplanes with no auto throttles, the A/P is hunting glide slope with pitch alone. On most instrument approaches in the soup, you are maintaining your approach speed until you break out or get to DH. So when you arrive at DH and want to start slowing down to land, you may find that you have a lot of nose down trim to overcome. Just adds to the workload if you wait until DH to kick it off. Bottom line, know your airplane and account for it if necessary.

My 55X has elevator servos as well as trim control. It will keep the aircraft trimmed quite nicely any time it is in one of the pitch mdoes.

I'm still confused over your statement. Even if the autopilot is using pitch to drive the elevator, if you've got the power back and it's in a constant rate descent, the thing should be trimmed fairly nicely for the airspeed it is maintaining.

 

[Fearless Tower]

I'm still confused over your statement. Even if the autopilot is using pitch to drive the elevator, if you've got the power back and it's in a constant rate descent, the thing should be trimmed fairly nicely for the airspeed it is maintaining.

If you are flying the approaching at 120 Kts, you are trimmed for 120. If at DH you kick off the AP and pull the power back to land at 90, you are still trimmed for 120 until you adjust.

 

[flyingron]

If you are flying the approaching at 120 Kts, you are trimmed for 120. If at DH you kick off the AP and pull the power back to land at 90, you are still trimmed for 120 until you adjust.

So? How is this any different for an autopilot versus hand flying? Even handflying, I'm trimmed for the approach speed.

 

[aterpster]

It wasn't the 767. The sim instructors were always prompting us to "brick your ship!".

Too many years flying Garmin trainers at my desk. The high-end Garmin autopilot, the GFC-700, has a sync-heading function by pressing the heading bug.

 

[Sluggo63]

It wasn't the 767. The sim instructors were always prompting us to "brick your ship!".

The CRJ has a push-to-sync. I think I've seen it on the E145/175, too.

I've never flown it, but I think the Airbus takes the heading bug away when in (L)NAV then brings it back synced when you select the heading mode.

The MD-11 was great in that respect. It would take the heading bug away when you weren't using it, and the next time you wanted it, it was synced to aircraft heading. It also has a feature that left a trail of dots showing which way it was going to turn, which was nice if you got a heading to turn "the long way around" you could just spin the knob in the right direction more than 180 degrees and the plane would follow instead of the stupid Boeing system where you have to turn 170 degrees, wait a bit, slew some more, wait, slew... The MD-11 really was ahead of its time. Much more advanced than any of the Boeing products up to and including the 777. I don't know... maybe the 787 is better.