NGX Final App. Help

[haztronic 1]

Hi guys,

this is my first time posting in the PMDG support forum and its to do with the NGX. I love this plane, absolutely fantastic but I'm having struggles with final approach speeds. To be clear, I have done some beautiful landings in the NGX and some landings I'd just love to FORGET.

Lately its been terrible, just now I finished a long route from Chicago to LAX in SWA's 737-700. Descent was fine, went along with my FMS calculations, speeds fine. But like usual, when at about 800-1000ft I disengage A/P and continue to follow the G/S by hand. But for some reason lately my speed just starts dropping like crazy and I end up either not making the runway or barely making the numbers. I don't understand why, I see videos of professional pilots on youtube and they have their final app speed of lets say 129 dialed in their MCP and hand fly the plane all the way down with no problems or increased loss of speed. But with me, I have to keep a high speed in my MCP because I know its going to for some reason just drop. Earlier I had 150 put in it and I ended up landing with a speed of 125kts.

 

I know its something I'm doing I just don't know what.

 

Thank you.

[Kerlix 99]

I'm sure you checked your throttle position? Sorry. Just starting with the most obvious. If you're fire-walling it and still losing speed, then something is definitely wrong on your end. Spoilers? I"m assuming their down.

 

I know that once you reach Flaps 30 (I believe), the A/T stops flying according to FMC speeds and you have to set VREF (or whatever you feel is appropriate) in the MCP. I know you're disconnecting A/P, but are you disconnecting A/T as well? If you are, and your throttle(s) is idle and you are expecting A/T to keep the speed up, well....there's your problem. You may inadvertently be going to idle and just bleeding off speed way too early.

 

If anything I said is wrong or in the wrong direction, please correct me. I'm tired....

[AirbusCG 52]

Hi,

please sign your (real) name to your posts according to the PMDG forum rules.

 

Next, could you show us a screenshot of your panel when in such a situation. This way it might be easier to find out what's going on.

[Boeing or not going 578]

If you are disengaging the auto pilot you should also be disengaging the auto throttle and flying completely manually. Keep a lot of power going because if you have full flaps you are going to be losing speed.

[rocketfs 2]

Hi,

 

For final appraoch, at a weight of about 58 tons, flaps 30 you can expect something around 57% N1 of engine thrust for a 3° glide slope.

When you disconnect the throttle, first make sure that the engine thrust is stable and that you have your throttle at te same position as the A/T was.

PMDG made a brilliant work-around for it by showing a blue circle showing your throttle position. I believe you have to enable that in the options.

 

Also a screenshot would help

 

Bert Van Bulck

[zubart 5]

It sounds like your autothrottle has been disengaged, but you believe it is on, If you intend on using the autothrottle to maintain airspeed during the approach, double check that the autothrottle is engaged. You may have accidently disengaged it when you disengaged the autopilot.

If that’s not the case then add thrust to maintain VREF +5. If you start getting to fast, reduce thrust. It's that easy!

Next time you fly an ILS, use the autopilot and autothrottle to capture VOR LOC and GS. Once established and stabilized on the GS, note what N1 thrust is holding the GS. This N1 target trust is a good ball park reference for all your ILS approaches. Now disengage the autopilot and autothrottle and manually adjust your controller thrust lever as necessary in increments to control airspeed. In normal situations, you'll just have to vary this N1 target thrust slightly. If airspeed is less than VREF +5, add just a little more thrust. If airspeed is more than VREF +5, reduce thrust slightly below the target N1 thrust setting.

 

 

John Floyd