Autopilot transition to APPR

Hello!

Am I the only one experimenting a weird transition while operating under LNAV/VNAV settings and then turning on the APPR?

For some reason when I’m normally following my flight plan and tune into the ILS to proceed with a auto approach the plane does a rude turn before doing it.

Is there a way to avoid it? Let me know!

Hi, when you engage APPR, how far out from the runway are you on the approach cone, is your intercept angle closer to, say, 30 degrees rather than very high like 90 degrees, and have you reduced to a “modest” speed?

This happens to me, usually the flight plan doesn’t follow the exact heading as the runway and is not 100 percent lined up with it, so when you turn on APPR is wants to correct the plane to be on the exact heading and wants it to be lined up perfectly

I know the science behind, but i thought about a “modest” turn though.

Well, as far as the cone begins I tune ILS the frequency and then I turn the APPR on, however, I have no idea about the exact distance, I’d say 5-7 NM though.

Haven’t check the intercept angle, as soon as I got centered the vertical indicator.

5-7 nm that’s way to close mate, to prevent from the hard turn, try to stabilise your altitude (3000-4000 ft AGL) before turning to catch the interceptor, then disengage the LNAV start the turn with the AP and then activate the APPR mode, everything has to be did before 10-15 nm.

Hi again, just to be clear, I’m talking about the horizontal intercept angle, like this:
image

You approach at level altitude as in:

with some angle inbound for the final course as in the diagram at top. Make sure your incoming angle is no more than about 30 degrees.

Then after hitting APPR as you near the final course (ILS localizer course), the AP should turn you smoothly onto the final course (as long as you are not too close to the runway or too fast).

If you move to the GS too early in your approach, the aircraft will sway with the altitude until about 3000 AGL; this is usually an issue at airports like KORD or KLAX with very long final approach courses.

The key to countering this is using an RNAV entry up to the final VNAV target and engaging GS when VNAV disengages. Or adjusting your speed with the altitude, which is harder to do but works very well if you know how to do it.

If the problem is abrupt aircraft maneuvers after moving to the GS, usually riding it out will help, but straight-in entries (from the end of the cone) also tend to remedy it. It depends on aircraft and airport.

Engage APPR about 3000ft AGL, and disengage it around 1000ft AGL depending on weather conditions. I try to avoid ILS unless FAA official d-ATIS says to use it, usually hand-flying it down from point of VNAV disengagement.

Thanks you all guys!

1 Like

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.