PMDG 737-900: strange behaviour at approach

[palafox 0]

I've been simming with this bird for a couple of weeks or so. Nice aircraft and, being familiar with the Wilco 737 Classic, the transition has been straightforward. My only issue is related to ILS approaches. Usually it works as intended, but from time to time, once armed the APP mode and when the locator is intercepted, or immediatly before that, the plane suddenly starts to climb, as if it would try to capture the glideslope. I've observed that this behaviour uses to happen when approaching at more than 3000 ft AGL, or when still descending to FAF altitude at the moment of capturing the LOC. Dunno whether this is significant or not.Thought that using the APP mode, the aircraft should capture the LOC and remain at the altitude set, until intercepting the GS. TIA,Jes

[basa 0]

Hola Jes

[falcon999 24]

I've been simming with this bird for a couple of weeks or so. Nice aircraft and, being familiar with the Wilco 737 Classic, the transition has been straightforward. My only issue is related to ILS approaches. Usually it works as intended, but from time to time, once armed the APP mode and when the locator is intercepted, or immediatly before that, the plane suddenly starts to climb, as if it would try to capture the glideslope. I've observed that this behaviour uses to happen when approaching at more than 3000 ft AGL, or when still descending to FAF altitude at the moment of capturing the LOC. Dunno whether this is significant or not.Thought that using the APP mode, the aircraft should capture the LOC and remain at the altitude set, until intercepting the GS. TIA,Jes

[palafox 0]

Hola Jes

[fencer 16]

Jes

[palafox 0]

Jes

[ronzie 21]

At some airports in FS the ILS frequency is duplicated at both ends of the runway. At default airports unrealistically in this special case the back course is still left on. When you are on your intercept course you may be picking up the incorrect ILS until with a couple of degrees from runway extended center line. Note the ident in your pfd before you enter app mode to insure it is correct.

[Spin737 102]

Jes

[downscc 1,327]

"Cleared for Approach" (ATC clearance received)

I've added this to my procedures after last year while on vectors for the approach at KHOU ILS 04, I armed the APPR but the controller intended to fly me through the localizer and turn me back on the other side for separation. She was very nice to me, but I had to be vectored outbound and probably spent an extra five minutes out there before she cleared me for the approach. Lesson learned.

[falcon999 24]

Where I work currently, you do a little check before you engage the APP mode: "INRR Identified" (Check the ILS ident) "Pointers in view" (make sure the LOC and G/S are displayed) "Intercept Heading" (Your track will take you to the LOC) "Cleared for Approach" (ATC clearance received) and then you arm the App mode. The only time I don't arm App is if we receive the instruction to "join the localizer." The B737 is configurable as to whether it will join the G/S before LOC capture.

Great check! Adding this to my flow, thank you. :( Flying an SR22 GTS Turbo with the Perspective avionics (similar autopilot functionality) I use the following autopilot modes:In general I use Heading, VS and ALT mode until:- When cleared for intercepting the LOC and level below glide slope: VOR/LOC and ALT, then APP when cleared for the approach and intercepting LOC- When cleared for approach, vectored for intercepting LOC, cleared for LOC intercept or Approach but above glide slope and descending: VS for decent, VOR/LOC when intercepting the LOC, once both LOC and glide slope intercepted (and cleared for the approach) APP mode (VOR/LOC if only cleared for LOC intercept)- When cleared for the approach, level below the glide slope and vectored for intercepting LOC. Heading and ALT mode, then when intercepting the LOC APP mode

[fencer 16]

Where I work currently, you do a little check before you engage the APP mode: "INRR Identified" (Check the ILS ident) "Pointers in view" (make sure the LOC and G/S are displayed) "Intercept Heading" (Your track will take you to the LOC) "Cleared for Approach" (ATC clearance received) and then you arm the App mode. The only time I don't arm App is if we receive the instruction to "join the localizer." The B737 is configurable as to whether it will join the G/S before LOC capture.

Hi Matt,Talked with an ultralight pilot friend who also happens to be an Airbus captain (A320 series) with a large european airline :- very similar procedure but they are not allowed to engage APP as long as LOC is more than one point from center.- doesn't know if it's possible to prevent the Airbus from joining G/S before LOC capture. If this option exists, it is not implemented in this particular airline. Rgds,Bruno

[Spin737 102]

Hi Matt,Talked with an ultralight pilot friend who also happens to be an Airbus captain (A320 series) with a large european airline :- very similar procedure but they are not allowed to engage APP as long as LOC is more than one point from center.- doesn't know if it's possible to prevent the Airbus from joining G/S before LOC capture. If this option exists, it is not implemented in this particular airline. Rgds,Bruno

I think the difference in technique may stem from the different definitions of "established" are for the LOC. I'm a little rusty on my FARs and I really don't know PAN-OPS at all, but I think in the FARs, established is "positive course guidance" (i.e. needle movement) and elsewhere it's one-half dot deviation. (Caution: Not to be used for actual navigation purposes!)