Hello everyone. I have encountered my first minor problem with the 737-700, since I bought it when it was first released a long time ago. I programmed a flight tonight, as usual, into the FMC. I got up to altitude, FL310. Everything looked fine, LNAV going great. I noticed all of a sudden, that I was slowly climbing, to FL322, or FL325. I decided to try something. I put the sim in 4X, and the plane clibmed and descended wildly! All the way up to FL350, down to FL200. Whats the deal? Did I miss something? It worked every other time except tonight. Thanks for your assistance. Joshupdate - I loaded a different flight plan, and the altitude was maintained (FL310). I must have messed up in the above mentioned flight plan. Wild stuff.

Did you use real world weather or did you have the pressure set to standard. Just a thought.

Real world WX and 29.92 above 18,000 feet as standard. And just as I said it was doing well, happened again today. Would not stay at flight level. I dont know what the problem is. Josh

Take a screenshot of the panel the moment this happens with the FMC open on what phase of flight you are in, and please do not hav it covering the MCP of PFD ;-) when you take the shot.Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/Animation1.gifCaution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |

will do....thanks for your help....screenie is coming shortlyJosh

OK, here it is. The phase was in cruize, so I put the FMC on CRZ. I hope that was correct. I planned for FL330 and as you can see, without any input from me, she climbs. And altitude hold was engaged, the light was just off. I use Vertical Speed hold of +1500 fpm, all the time, to get up to altitude, then the AP captures by itself upon reacong the desired flight level. However, after about 10-20 mins at desired FL, she starts climbing with no reason what so ever.Josh

Couple of things here Josh,- Your speed is set to 0.25Mach in the MCP. Why?- You have no Auto Throttle engaged. How are you managing speed?- Flight Director is not set ON. - STD pressure is not set. Should be set above FL180 in North America or approx FL50 in Europe.EDIT: I see you have the baro set to 29.92 though. Which basically will do the same as setting STD.- Have you checked your weights? I see you have almost full fuel tanks.- I also see that you have full throttle, you are climbing and the speed is dropping. This could also indicate some overweight problem.Unfortunately the FMC is covering one of the most important parts of the Primary Flight Display. In the top of the PFD you have the Flight Mode Annuciator, or FMA for short. This is where the autopilot will tell you what mode it is in. Can you remember what it said at the time of the picture?All in all these above items indicates that the issue at hand is some kind of misconfiguration or mishandeling of the aircraft. Try reducing your fuel to 50% in each main/ving tank and a 1000lbs/500kg of fuel in the center tank. Also check your pax/cargo load and set it to some 20000lbs/9000kg either from within FS or via the load manager. Also engage auto throttle and flight director and make another try.Hope it helps,

Airspeed has hit the barber pole, apparently at full throttle and with Alt Hold on. Without seeing the FMA it's unclear what the aircraft is trying to do. Any reason why it would climb to try and prevent overspeed? Just a WAG - I've not flown the NG without some form of speed management (mode) being enabled.

Hello Mats, thanks for the help! I just noticed that the FMC hid the FMA, sorry about that. When that picture was taken, I just had the ALT lit up and the LNAV on the FMA. I tried everything you mentioned, to the TEE, and for some reason, it still descended and climbed without my consent. I activtaed the auto throttle to hold mach .80, the flight director was armed, pushed the baro to get it to STD pressure, and had the lnav going. It worked for about 20 minutes, then started step climbing, and step descending. Strange stuff here. I will have to just try some more loading situations and maybe try to build the flight plan again. Thanks for everything!Josh

JoshGimme your a/c type, weights, fuel load and the complete flight plan with all perf init data and I'll load it up and see if I can recreate the problem at my side.Oh and can you attach your aircraft.cfg for the selected aircraft as well? Hmmm. Another question arises. Does this happen with any type of NG? If not which ones?Did you say you saw this with real weather? What happens if you disable the weather? Can you see a difference?Hope it helps,

DrJimi,EXACTLY ! The plane is overspeeding for more than the allowed time in the "red" area as per manufacturer manual. The automatic flight system is trying to save the plane from overstressing. If the AT is engaged the throttles are automatically commanded to maintain the barber pole minus a margin and if this is not achievable within a flight-phase dependent time then the AFS reverts to ** unconditional ** pitch-for-speed (barber pole) UP with throttles commanded to idle (something like LVL CHG up with thrust to idle)! Nice eh ? In this case the pitch up sequence works but not the AT.Best,(dr)EV :)PS. I wonder how many of these more intricate features have been explored by "virtual" captains !===================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com=====================================

Dr Vaos!That was a truly amazing fact!!Cheers,Mr Johansson, B.Sc

Will do, let me go grab the info for ya :)

OK here we go:Weather - FS Default real world weatherA/C Type - 737-700, 737-600Weights - 104,526 lbs w/o fuelFuel Load - 46,045.78 lbsGross Weight - 153,500 lbsFlight Plan - KDEN-EPKEE-GCK-IRW-EIC-AEX-BTR-VOODO-KMSYFlight Level - FL330Aircraft CFG - attachedHope that what you needed.

Josh,I did recreate the flight and I agree with Dr. Vaos on this one. See his note to you here: http://forums.avsim.net/dcboard.php?az=sho..._id=65002&page= The climbing you see is the AFDS protection against overspeed. As you don't have the auto throttle set the only way the automation on the aircraft can protect it is via climbing. When I then suggested you use the auto throttle I guess you switched it on but didn't set any mode. Is that a correct assumption? Because this will show the same behaviour as without the auto throttle set. With A/T mode set to speed and speed set to 0.78M the throttle closed to slow down to target speed and the craft pitched down to reach target altitude. Once on target speed and altitude it was a walk in the park.So the bottom line here. Monitor your speed or set the auto throttle to do it for ya. And don't forget to tell it what mode you would like it to operate in. In cruise that would be SPD or VNAV. The former is a clean throttle mode while VNAV is a combined pitch/throttle mode.Hope it helps,