Hello,

 

I recently did a trip from Las Vegas KLAS to Los Angeles KLAX, using departures and arrivals as follows.

 

25R Departure

25R Arrival

 

Using

 

BOACH4.HEC ... HEC.RIIVR2

 

All goes well until approach, where at SHELL, the plane just starts to dive into the ground, no disconnects, or mode changes. I have to quickly go into Vertical Speed and set it to not crash. Monitoring the approach, the descent path is perfect, well at least until SHELL. Hopefully this is user error here. I tried the same flight twice to the same end.

 

And insight to this problem would be greatly appreciated.

 

Adam Blanchette

Well the first thing I'll point out is that with very few exceptions LAX always lands on the outer runways (24R and 25L).

 

The other thing is this: when you begin receiving the Localizer (as long as you're cleared for the approach, which you would be in this case. You'd hear "Descend via the RIIVR2 arrival, then cleared ILS runway 25L approach") you should change from LNAV to LOC, then when receiving the Glide Slope (and below it) you should change to APP mode. You shouldn't be using VNAV all the way down on an ILS. In reality I believe the localizer reaches all the way out to RIIVR (or close to) but due to a limitation in FSX, it does not in the sim.

Actually you should use VNAV all the way down to FOGLA for 25R or LIMMA for 25L. If you follow the GS down from all the way out it will take you below one or more the step down altitudes on the approach. Pilots have been viloated for doing that. I'm based at LAX so I fly it all the time. I leave it in VNAV until between HUNDA and LIMMA. If I was flying 25R I would arm APP between SHELL and FOGLA. Every once in a while they will clear you for the visual and to follw the GS from way out but if you don't have that clearance you must honor all of the step down altitudes limits.

 

Your technique for flying the approach is correct it seem so there may be some other issue going on.

Hi..

 

I do not receive localizer or glideslope till around Shell.. looking at the descent path with the display on the PMDG 737NGX the plane does a nosedive -before- glideslope intercept. I do not remember if I intercepted the localizer, though I believe I did. I am using vnav/LOC all the way to G/S intercept., I do not even have time to intercept the glideslope before the plane nosedives... mind you .. there are no disconnects, with the autopilot, LOC, or any of the modes. Not even 1/3 mile before glideslope intercept is when it nosedives, forcing me to go into V/S mode and correct before the plane crashes.

 

Looking at the approach plates for 25R I notice intercept is at FOGLA. I do not even get that far.

 

EDIT: I'm using FS2Crew voice.. and when he says LOCALIZER alive I intercept.. as its basically a straight in approach.. then when he says G/S alive. I'm under the interception.. on my descent from SHELL to FOGLA.. just before I can intercept, right before FOGLA the plane starts its nosedive of death. Unless I'm wrong.. I'm under the impression that I cannot intercept the G/S while it is above. might be wrong here. So I wait till its in the center of the display, not above.. before I intercept. Can I intercept when I'm under the G/S or no.. either way.. I do not believe that the plane should be nosediving before the G/S intercept.

 

On a different subject.. On my descent, no winds, I am having a hard time slowing the plane down, always getting "drag required" even with speedbrakes on as far as they will go, I usually end up with a cannot achieve on the fms and end up having to manually correct. I thought this was not supposed to happen with no wind, just with a major tailwind or crosswind with no winds entered in.

KLAX ILS Glideslope for 25R/L is unusually long (40NM) which FSX default does not model (23nm) (Not sure about FSDT KLAX). so that may be your problem. If it is you can edit the AFCAD with ADE (or whatever editor you use) and extend it. This is what I did.

KLAX ILS Glideslope for 25R/L is unusually long (40NM) which FSX default does not model (23nm) (Not sure about FSDT KLAX). so that may be your problem. If it is you can edit the AFCAD with ADE (or whatever editor you use) and extend it. This is what I did.

 

I have the FSDT airport, I understand what you are saying.. but either way shouldn't the VNAV at least take it down to my set alt .. no matter what? Not nosedive into the ground?

 

I looked into the fsdt afcad.. and it is default.. extending it however would still put it above my descent path.. no?

 

EDIT: tried editing the afcad.. ADE will only let me set it to 30nm.

Actually you should use VNAV all the way down to FOGLA for 25R or LIMMA for 25L. If you follow the GS down from all the way out it will take you below one or more the step down altitudes on the approach. Pilots have been viloated for doing that. I'm based at LAX so I fly it all the time. I leave it in VNAV until between HUNDA and LIMMA. If I was flying 25R I would arm APP between SHELL and FOGLA. Every once in a while they will clear you for the visual and to follw the GS from way out but if you don't have that clearance you must honor all of the step down altitudes limits.

 

Your technique for flying the approach is correct it seem so there may be some other issue going on.

 

Learn something new everyday. Thanks for that, Tom. I know you don't get the North complex as much if they can help it, but does 24R have that problem as well?

Learn something new everyday. Thanks for that, Tom. I know you don't get the North complex as much if they can help it, but does 24R have that problem as well?

 

Yup as I understand it that will happen for all the westbound ILS approaches to LAX.

I just did 25L a few days ago, and kept it in VNAV until LIMMA or somewhere around the FAF. They vectored us for a 30nm final, and I never saw a fix that was above the G/S. I didn't want to test it, however.

It's one of the closer in ones like GAATE or HUNDA. My brother heard a crew get nailed on that one day going in there.

It's one of the closer in ones like GAATE or HUNDA. My brother heard a crew get nailed on that one day going in there.

Just looked at my company page, and yep, it says no G//S prior to GAATE.

I used to have an issue with nose-dives. It used to happen when I disconnected the AP to switch to manual-flying the approach. I would turn off the AP at 2,500 or so and the plane would throw itself 60+ degrees nose-down and no amount of back-pressure, flaps, or trim would stop me from slamming into the ground.

 

But it's never happened with AP ON, as you've stated.

 

What fixed it for me was a simple re-install. Never had the issue since.

No problem with this flight. I just did it with default MS fair weather and a heavy loaded 738. There might have been a moment where it could have been above the path (about 430 ft) while it tried to decellerate due to to the 10000ft speed limit, but I decided to support the dive by applying the speed breaks. The rest was business as usual, by the way without extending the ILS range even if I'm quite used to work with ADE.