Autoland Climb on 737

[Guest rontheancient]

Hello, im new to the PMDG support forum but have been flying the 737 600-900 for almost a year and recently a problem as surfaced with the autoland function.I perform a normal autoland with all the procedures done, correct altitude, speed, and both NAV radios tuned as well as the REF selected in the CDU. Then, I press APP and the second AP and I get the SINGLE CH message in yellow and for the next minute or two it looks like the plane is following the G/S but 10 miles out the 737 makes a abrupt climb putting the A/C into a stall, this event has also happened in the opposite direction, where the plane dived into the ground.This happens most frequently at the Cloud9 KLAX, but it has also occured at the FlyTampa KSFO. However, I was able to make a successful ILS landing at the FlyTampa KSEA in the 737 and another successful landing at the Cloud9 KLAX using a LDS 767. Right now, I cannot tell if there is a problem with the scenery, the plane, or how I am prepping for the Autoland. Help is much appreciated, thanks.

[Guest tomahawk_pa38]

You haven't descended too low have you and therefore the plane climbs to intercept the glidepath ? You need to put the FAF altitude in the altitude box and descend to that level before hitting th Apr button otherwise it will climb.PS - You need to sign your name - forum rules.

[basa 0]

Yes, the same happened to me trying to land in Bremen (EDDW) with the wonderful scenery by Oliver Pabst.I never had problems with other aircraft at EDDW, but, for almost 5 times I tried to do an ILS approach with my PMDG-737 there.It was impossible !!!When I was fully stablished in the glideslope with my 737 perfectly configured for landing, suddenly the acft started to climb and climb and climb...So, after many attempts I had to stop flying to Bremen with my 737.As far as I know, some complex sceneries have an strange interaction with the PMDG-737.I have also read about a module called "perfect gate" used in some sceneries interferring with the PMDG-737.Jose Luis.

[Guest rontheancient]

>You haven't descended too low have you and therefore the>plane climbs to intercept the glidepath ? You need to put the>FAF altitude in the altitude box and descend to that level>before hitting th Apr button otherwise it will climb.>>PS - You need to sign your name - forum rules.I followed the altitude restrictions on the charts for both the approach and the runway. Also, sometimes when I activate APP, the plane suddenly descends rapidly then goes back into the climb. What is FAF altitude?Ron

[Guest woottsbj25]

FAF is Final Approach Fix - the last fix on your approach segment. There is an altitude constraint for that fix, and that's what you need to be maitaining when you hit that waypoint.

[Guest rontheancient]

Im still a bit confused. So would the FAF for a airport/runway like 25L @ KLAX be FUELR or the altitude of the runway, 101MSL?Ron

[Guest tomahawk_pa38]

Can't say for KLAX exactly but if you look at your ILS approach chart this will show the FAF and the altitude you have to be at.

[Guest woottsbj25]

No, it's not the runway. When you set up an ILS approach using the FMC, a number of waypoints come up. The LAST waypoint BEFORE you reach the runway is the FAF - i.e. the last waypoint you come to before you're headed direct for the runway. There is an altitude constraint for that waypoint, if you look at the charts.

[ronzie 21]

This approach is a bit more confusing at KLAX. If you look at the chart the IAF is POMONA VOR (not labeled as a VOR) or SEAL BEACH VOR northeast or southeast of the final inbound course. FUELER intersection is also an IAF. The published altitude from POMONA to FUELER is 8000 (not shown as a minimum on my chart).The FAF as noted by the "Maltese Cross" I believe is LIMA at 1900.Note the minimum altitudes listed at the intersections along the localizer. The are for localizer only (no G/S) on the inbound course.Note on your plate the minimum altitude 25 mile quads based on LAX VOR. POMONA and FUELER are outside the 25 nm limits so you need tgo pay attention to the 8000 minimum until within the areas defined with the 25 nm radius. If you are being vectored to the ILS merge from the south at SEAL BEACH the MSA is 2700 so you can descend from there to that altitude to merge at HUNDA at 3200 ATC permitting.Looking at the inbound course vertical profile you can see that the descent before LIMA is shallower and the G/S actually intersects with the published altitudes at the FAF of LIMA. You will find the G/S if detectable at the indicated altitudes further out from the FAF above you which is what you want to catch it.The slope of the vertical path changes because of obstructions, nearby traffic, or other constraints.

[Guest rontheancient]

Thanks for the help, I will do a test flight and will report back soon.

[Guest rontheancient]

Well, I flew a short SFO-LAX flight and no joy. After I activated the APP and reset the ALT indicator in the MCP to the published FAF altitude, the plane made a quick descent and arrived at 1900ft 5 miles before it even crossed the FAF. From that point all the way to the runway, it just stayed there, shortly after crossing the FAF, the G/S disappeared from the display. Also, the second autopilot went out, but the VOR LOC was on. Im thinking that I need to reset the ALT indicator in the MCP to runway height after crossing the FAF, am I right?

[Guest woottsbj25]

AFAIK, it shouldn't matter what is in the ALT window after APP is engaged, but please excuse me if I'm wrong.Sorry I can't be of further help.

[Guest Loiosh]

You are correct. She will only descend as far as you tell her its safe to go.

[ronzie 21]

1. Where and at what altitude did you intercept the inbound course? 2. At the intercept the GS indicator should be above center.3. Make sure that the correct localizer ID is on the below left side of the FMA. Make sure the MCP course setting is correct for inbound.4. Just before the merge make sure as soon as the localizer H indicator starts moving you have the aircraft turned with heading to within a few degrees of the inbound.5. Only after the correct localizer ID is insured and you are turned close to inbound and the GS indicator is above center engage APP.I am puzzled by your comment about reaching 1900 before the FAF. If you are in using FLCH it will go down to 1900 ASAP from wherever you are and stay there until you engage APP. If you are in VNAV it will do the same unless you have loaded in the DEP/ARR destination RWY an IAP that includes altitude restrictions that follow the vertical profile. (Some airlines have a policy of disengaging VNAV below 10,000 feet and at some point going to HDG for steering then manual flying the aircraft until the localizer is captured followed by GS with APP engaged when in the final stages of GS merge.) If not the aircraft will descend according to the descent profile directly to your MCP ALT setting.You need to study up on the FMA readouts and how to interpret them. They will show you the modes that the aircraft is following. You can use this to see what went wrong.There is _also a bug_ in FS9 default airports that when the localizer/GS shares the same frequency unless you are right on the intended beam it will lock on to the back course of the opposite localizer. That is why it is important to check the localizer ID below the FMA to insure you are going to lock on to the correct one. It sounds like you locked possibly on to the "ghost" beams of the opposite one to early in the approach. Use AFCAD to check out the airports you use with shared frequency opposite end localizers and turn off the back course property using the runway properties tool. That should get rid of "ghosts" on inbound. I do not bother with most of them just using MPC HDG and ALT until I'm centered on the localizer with the GS above turned inbound AND THE CORRECT ID. Only then do I engage APP.In the June issue of Computer Pilot Mike Ray has an article on interpreting PFD (Primary Flight Display) including very good info on the readings I suggested you check above. especially your status on the FMA section.

[Guest rontheancient]

ronzie,I merged into the lineup for 25L at GAATE @ 5000ft from JAVSI. At that point, I activated APP, the second autopilot, and reset the ALT indicator. Also, I checked the localizer ID in the display, it showed KLAX or something to that nature. As for the altitude issue, SPEED and APP were the only ones on when the plane made the descent to 1900 and that only started when I pressed APP (it started with a sudden jolt downard).I will try again later today with the new procedure and report back.Ron