Jump to content
Sign in to follow this  
Guest spiers

747-400 pmdg vnav altitude error?

Recommended Posts

Guest D17S

Hey, if you are getting the three autopilot lights to come on when you press APP, you are doing something very well. That means the airplane has accepted your request to do an "autoland." Once those 3 lights come on, all you have to do is 1) Make sure the autohrottle is engaged 2) Get the flaps and gear down out 3) Arm the autobrakes and spoilers 4) And slow down to landing alrspeed. (Here's how find out what your landing speed should be and then how to control airspeed with the autothrottle) Your landing speed is shown on the FMC's approach page. Get there by pressing "Int Ref" (upper left button - on the keypad). You will see speeds for flaps 25 and 30. Select one to the scratch pad then into LSK 5L. A new bug just appeared on your speed tape showing this speed. This is your target landing speed. First bring the flaps down to either 25 or 30. With the autothrottle engaged, use the MCP airspeed knob to slow down to this speed. Then just sit back and watch the action. Don't try to drive. For now, just keep your hands in your lap! The airplane will land itself.

Share this post


Link to post
Guest spiers

I landed at the vref speed and it still went up into the air. So i pushed the nose down and the AP disconnected leaving me once again to use the parking brake to stop at 120 knots. Just a question i was looking at the PFD and the rollout was under something called LOC which means Localiser doesnt it? When im doing an approach do i need engage this for the plane to land and stay on the ground? Whenever ive engaged LOC im sure the APP turned off. Any of you got MSN so i can send you a video of my approach and landing?Really dont know why its happening, its almost like the wheels are too long and touching the ground earlier than expected.*************** EDITCant seem to playback my video through FS anymore, not even one i made a while back which IM SURE works, might work on someone elses FS though, I did crash which might break it?

Share this post


Link to post
Guest D17S

Having a white "ROLLOUT" under "LOC" is exactly what should display. Good! LOC is Localizer like you described. This is what the middle FMA (Flight Mode Annunciator) describes for you. The middle FMA describes your roll mode. It's how the AP is steering the aiplane. The Localizer steers the airplane back and forth during approch so you stay lined up with the runway. Once you actually land, the white "ROLLOUT" will replace LOC and become the active steering mode. This will keep you on the centerline as you rollout. So far, so good. Now the up and down part. Right FMA is called the pitch mode. What's in there? It should be "GS" (Glide slope) with a white "FLARE" below it (like the white "ROLLOUT " next door). This FMA shows the autopilot's roll mode. This is the way the AP keeps the airplane descending at the proper angle to land at the end of the runway. At about 20 feet, FLARE will replace GS in the pitch FMA. This means the airplane is now flaring to reduce the rate of descent . . . . to prevent a bounce!!! Is this hapening? . . .not the bounce (sounds like fun actually), but the annuniciations in the pitch FMA? What's showing in the pitch FMA? Now, the far left FMA. This is your autothrottle mode. What's in there. Should be "SPD". Then shift to "IDLE" at touchdown."CMD" is annunciated below the three FMAs when you are above 1500 feet. This means the AP is controlling the airplane. At 1500 feet, it will shift to say "LAND 3." Until now, the three lights in the AP buttons were just the airplane's way of making you feel better about your request to do an autoland. When you finally see "CMD" replaced by "LAND 3", this means those other 2 autopilots are now REALLY hooked up. All 3 autopilots are now on-line. The AFS has "Made it's list and checked it twice." This is the AFS's final declariation that it is ready to do an autoland. You must see "LAND 3" at 1500 feet. Bounces can happen if an approach is not stable, even with an autoland. Just to get it working for now, the best bet is to get the flaps and gear all set up for landing, and the airspeed slowed down to landing speed . . . several miles before the runway. My company tells the pilots that they must be fully configured and stable by 1000 feet AGL or they MUST go around. For now though, get yourself stable long before that. The airplane will seem to just hang there, but just let it. At Vref (+5), with gear down and flaps at your landing setting, the airplane is completely safe and stable. See what happens.Also make sure MSFS's winds are set to ZERO for now. (Once you get it working, try an autoland with a 30 knot cross wind. Snap an 'above and behind' screenie at right at touchdown. Very cool.)Don't know how to move videos around. Maybe someone could help with that.

Share this post


Link to post
Guest spiers

All you have written seems to be happening. The FLARE definately shows up, when it does the plane descents slower trying i think to make sure the back wheels touch down first. About getting it stable i have tried getting gears and flaps set also speed before im even on final. Then the plane turns onto final and takes at LEAST 3 minutes to actually touch down, this is at 140 knots though which is quite slow.Land 3 definatly shows up, i think it changed from Land 1 to Land 2 then to Land 3 while getting closer to the airport. Just asking what does VREF+5 mean?About the video, any stored videos are normally kept in the folder "flight simulator Files" in my documents, i can send you them, but they can only be viewed in MSFS as ive tried with several media applications to play them. When i was having trouble with a checkride i zipped the video file and sent it to him, size was less than 1MB. I set the weather to fair, which seems to be default, however flying online also causes the bounces, and online im sure everyone must have the same weather. They were joking because i couldnt stop before the end of a 10,000 feet runway, 21L at Johanasburg. I didnt find it funny at all.Using FsPassenger using the parking brake while at speed is illegal and gains a fine and somethings damages the aircraft, why does the auto-brakes disengage even when i hit the ground? I thought there turned on automatically when your wheels hit the ground, but they disconnect once im in the air again.Thanks for your continued support.

Share this post


Link to post
Guest D17S

Making good progress. If all this is happening, things are working quite well. "Vref" is just a slang term for any airspeed that is being compared to something. By itself, it really has no meaning. It must be used in a context.Here, we are using it to compare an airspeed (that's the "V" or velocity part) to the landing airspeed that should be used for various flap settings (that's the "ref" part). In our case, the 744 uses either 25 or 30 degrees of flaps for landing. Remember how to see what the FMC calculated as a correct landing airspeed for the 2 different flap settings we have available? It's on the FMC's approach page. Get there with the INT REF button on the FMC. Now decide what flaps you want to use (doesn't matter for now. 25 or 30 are both OK), and set your MCP airspeed window to that airspeed, plus 5 knots. That's the meaning of "Vref+5" in this case. But keep in mind that Vref+5 could mean something entirely different in another conversation. The +5 knot is just a real world safety factor in case there's a bit a wind at the end. It will make No diffecence to your landing outcomes (yet). That 140 knots is a Vref for either flaps 25 or 30 right? If so, sounds like you

Share this post


Link to post
Guest spiers

Landing Touchdown:-540.77 ft/mLanding Pitch: 2.51

Share this post


Link to post
Guest D17S

You've arrived. That's a perfect autoland about to happen. Sounds like a little work on throttle control and you'll have it. Go into the PMDG menu selection at the top of the MSFS screen (keystroke "Alt") when you're flying. In the General>Options>AFDS drop down, you'll see "Control Override." Make sure "Throttle" is unchecked. That will prevent any user input (Playstation controller? -- Who knows, but one can hope!) to mess with the autothrottle when it is engaged. There's an on going issue about hard landing with the PMDG model. The first time I autolanded, I was sure I had crashed. Flare seemed to do nothing to arrest the ROD and I landed with a big bang. I bounced so high that the airplane thought it needed to do a go around. Thrust went back toward full power and off the end of the runway I went. Sound familiar? PMDG reduced the autoland ROD at landing with the latest 747-400 patch. They say it's a MSFS>PMDG interface problem. The patch really helped a lot.Arm those speed brakes and when you touch down press F2. That will get the reversers out. At 80 knots press F1. That will stow 'em and get you down to ground idle (25% N1). That should do it. (Now all you have to do is pass that silly math test!) Nice work.

Share this post


Link to post

Your problem may simply be that your joystick throttle is interfering with the PMDG A/T wanting to reduce the throttles to idle. Make sure you pull back your joystick throttle to idle before IDLE is annunciated.With the thrust levers not at idle, the speedbrakes will not autodeploy and the Autobrakes will not operate.In the real world, thrust lever position is the key, but in sims, it is usually actual thrust.... so you must give the engines plenty of time to spool down. Sometimes you have to calibrate your joystick throttle with a large margin for error. The full (electrical) idle command has to be at a position reasonably far forward of the joystick thrust lever aft stop.On the 744, for the automatics to happen, there are various prerequisites (too complicated to mention here, but a lot of them are modelled in PMDG). The Autospeedbrake requires that your thrust levers are at idle and that certain combinations of main gear bogeys have become untilted (NO wheel spinup is required on the 744 for Autospeedbrake as previously suggested). Autobrakes on the other hand, do require wheel spinup... and allowances are made for some burst tyres so don't worry ;)If you do land with the thrust not at idle and bounce, then you've got a lot to think about, as you will have to rearm spoilers and autobrakes. They don't rearm themselves.... so if you don't do a go-around, you will have to apply these manually.If you ever get to fly a real 744, in some ways, you may find it easier than flying your sim... You don't have to circumnavigate some of MSFS's shortcomings ;)Hope this helps.Cheers.Q.

Share this post


Link to post
Guest spiers

Now i turn the thottles off, so i cannot mess with them at all, the only problem with that is then the reverses dont turn off as i cant apply any throttle at all, i'll try pressing F1 at 80 knots see if that works. Im sure the AP boxes are unchecked, but a few times (especially when i pull the controller out without pausing, the planes AP disconnectes and dives to the ground! I'll check the option again, but really i dont think the throttles are a problem anymore. The plane doesnt bounce that high but its definatly off the ground, the one time it came back down itself was when i applied reverses, i might apply them when the FLARE starts and see if i can keep on the ground, weeks ago i was thinking of stalling it so there was no way it could gain height, but i think thats a little too desperate. Im sure ive got the patch, but also i'll check that. What i would like to do would to just pratice an approach again and again, like with the training in MSFS, because taking off then landing just to see if i can stay on the ground is rather time consuming, if im on the final approach, can i save the flight, and it will start me from there? or will it take me back to the depature Airport? Ive already saved a "ready for takeoff" panel it was taking me so much time to set up the FMC and other things.Thanks again, hopefully in another week i'll have this sorted out!

Share this post


Link to post
Guest D17S

Sure, save a flight during final, or anywhere of interest. (Just name them so you can remember what they are. You

Share this post


Link to post
Guest D17S

"SID (standard instrument arrival)" Oh geeze! Sorry bout that. That

Share this post


Link to post
Guest spiers

Landing Speed:144.90 ktLanding Touchdown:-222.31 ft/m (nice)Landing Pitch: 2.32

Share this post


Link to post
Guest D17S

Yep. That's the way it's done. Great job! I'll check out that EGTN>EGCC run. Always looking for a reason to fly somewhere.

Share this post


Link to post
Guest spiers

Landing Weight: 287408 kgLanding Pitch: 3.65

Share this post


Link to post
Guest D17S

And that's just how an experienced captain can make $250K+/yr. All in a day's work.Might be going back for some more MD11 performance training this week. I make them totally crazy because I always want to know why, why, why? I want to know the engineering / math behind it. They say "Stop already. Just do the chart! We don't teach pilots that stuff because they don't need to know it and especially, we don't want them second guessing it on final approach." I've had some animated conversations with Boeing instructors about this and I'm leaving my calculator at home this time. If I'm nice, I might get to fly the real-deal, MD-11 simulator! That's much more fun than saving the world! Now that you're getting the airplane down, time for some ATC fun. Practice clearance read-backs:C.R.A.F.T =ClearanceRoute AltitudeFrequency TransponderFind a Clearance/Delivery stream at the Live ATC site and listen in. CRAFT is the information sequence. The Departure route will be your SID. Altitude is initial altitude after TO. Frequency is your departure frequency. Set transponder as instructed. Then on to VATSIM:http://www.vatsim.net/There will always be more to learn. Hopefully

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
×
×
  • Create New...