FMC freeze on 777 (with Sp2)

[guy 24]

I just wanted to signal that I had still several complete FS9 freezes after doing modifications in the FMC of the Pss 777 (with Sp2).Each time it happened when on approach I modified speed/altitude restrictions in the Cdu ,for example from 210/4500 to 220/5000. I had it with the 200LR and also with the 300ER version.I had to cancel and restart FS9 each time.Otherwise it is a fine plane. Just a pity that there are still those small bugs.Regards.Guy

[FOD 23]

Guy,Could not find your previous posts - as you know this was a problem with the early 777 but seemed to be resolved. There have been similar problems since but only with specific scenery/navdata.Can you let me know the route where you get the freeze and I will try and reproduce it.RegardsJohn Rooum

[guy 24]

John,Thanks for the interest.The two times I had it now was when flying into Hongkong-Kaitak (VHHX) using the free Kaitak98 scenery (btw,very good!).The approach to runway 13 goes CH(Vor)-Golf-SL-Iaf13-Lda13.I had programmed a hold at CH.The freeze happened each time when on approach I tried to modify the speed/altitude of the hold (there were still other waypoints before CH)The last time I had made a short hop Guilin(ZGKL)-VHHX using the flightplan generated by FS9.Could it have something to do with the addon scenery? Difficult to imagine!Guy

[FOD 23]

Hi Guy,Been up to my elbows in FSX SP1 for the last 24 hours. However, I have found Kaitak98 and will have a look at your routes over the next couple of days {it will be a rest to get back to FS9/777 again!!}.RegardsJohn R

[guy 24]

I had a new freeze now on the ground(!) at Kaitak (Vhhx) while preparing the FMC for a roundflight over Hongkong with again a hold at the CH Vor.And again it happened when I Modified the parameters (speed/altitude)of the holding point.Guy

[guy 24]

I had the freeze now also at other places.So it has nothing to do with the Kaitak scenery!It happened each time while preparing the FMC on the ground i tried to introduce a holding point at the destination airport.(for example VGZR-VNKT with hold at point Nopen before Vnkt)When I initiate first the performance page and then introduce the hold, it freezes when I indicate the holding point.When I introduce first the holding point and then only initiate the performance page it freezes when I initiate the performance index.As I cannot restart the computer all the time, I think I will no more use Holds with the Pss 777 .Guy

[guy 24]

While on cruise between VGZR5(Dacca) and VNKT(Kathmandu) I could not resist to make another test.The point NOPEN i mentioned before is part of the ROMEO approach to Vnkt and has a height restriction of 11500 feet.(the following and final point CF02 has 6990 feet)Now, this time I first deleted this height restriction (it passed to 8590) and then I introduced the holding at Nopen without problems !Then I introduced the Height-restriction of 11500 feet at the waypoint Nopen. This was accepted, but the height of the holding point Nopen itself passed to 55640 feet!When I tried then to modify the restriction of the holding point back to 11500 i got the FREEZE again!So there seems to be a problem with holdings having height restrictions!Guy

[guy 24]

As a conclusion it seems that there is a problem in the computation of the altitudes of the different waypoints. When there are already other altitude restrictions, then, under certain conditions , the program loops!Concerning the hold itself, the plane does not seem to follow the holding pattern (after the entry procedure).I would say it rather flies around in the vicinity of the holding point!Guy

[FOD 23]

Guy,Concerning your last, the 777 does seem to follow the holding pattern. But the rate of turn programmed into the autopilot {approx 22 degrees AOB} is insufficient to follow the magenta line drawn on the ND.As the the freezes, I have now flown some ten routes looking at the problem and am airborne at the moment. This time I am using your short route but have set the hold at TD.I will summarises everything I have seen in this post shortly.John Rooum

[guy 24]

I did a last test.On the example of the flight VGZR(Dacca) to VNKT (Kathmandu) the Romeo approach to RW02 to VNKT goes like this:Nopen /11500Cf02 /6990Rw02 /4390The Romeo approach has points before Nopen which I did not use.The altitude restrictions at Nopen and Cf02 are imposed by the procedure.This time I first deleted the restriction at Cf02. The altitude at Cf02 passed to 7700.Then I introduced the hold at Nopen and set the the Restriction to 210/11500. This went without problems this time!If you do not delete the restriction at Cf02 you will get a freeze when you set the restriction for the hold at Nopen.So this confirms what I said before: It is the other restriction at CF02 which causes the problems and makes the program loop.You can reproduce this easily while sitting on the ground at VGZR and preparing the FMC.Guy

[FOD 23]

Guy,Now completed 10 flights using your ZGKL

[guy 24]

Thanks John!I repeat, You can experiment all this sitting on the ground and preparing the FMC.No need to fly! I don't think at all it is a "Navdata problem" (whatever that means). I am almost sure it is a bug of the Altitude computation routine of the FMC. I have often seen that ,when I set an altitude in the fmc, the waypoint before or after get impossible values.The fact that everything is OK at VHHX when using the TD waypoint or at other places is probably due to the different distances between waypoints.A workaround is to set only one restriction in the FMC and use the altitude window of the MCP for the others, because restarting Fs or the computer is no fun.Guy

[guy 24]

I flew now from Vidp(Delhi) to OAKB(Kabul) with the pss-777. (I fly round the world in short hops of 1-2 hr).On the ground at Vidp I had placed a hold at CF29 (8 miles from RW29 of OAKB) and introduced the restrictions 190/8400 without problems ( as there are no other restrictions).In flight ,on approach to Cf29 (about 30 miles away), I had the idea to lower the altitude a bit to 8000. (Kabul is at 5900).So i tried to introduce 190/8000 at CF29 and what did I get? a FREEZE!And I repeat, this time there were no other restrictions!So I think this confirms well that this problem exists anywhere!Guy

[Guest gtsouza]

Hy,I

[guy 24]

I'm sure it is a bug in the FMC!I have read in the other thread (777 patch) that there is another patch underway. As this freezing problem can be easily reproduced with the examples I gave above, I hope it will be eliminated with the next patch.I managed also to fly now two more holdings with the 777. I must revise what I said before : this time the 777 flew them correctly. With reduced speed (190) the 200LR remained almost on the margenta line, the 300ER flew well also, just a bit large.I like the 777 especially because of the great cockpit(2d/3d) and also the acceptable frame-rates it gives on my older computer.Guy