I have been getting a message on FMC saying "unable crz alt" I have tried all alt from 2000 to 29000 and does not want to accept any. Has anyone seen this message , cannot seem to find the error in the documentation.Assistance appreciated

I haven't heard or experienced this before. You are loading the fuel from the PMDG menu and not from the FS fuel loader, right?

I take it this is referring to the 737NG, hard to tell in this forum format. Anyway, if it is, it means the following quoted from Bill Bulfer's guide:"FMC predicts the aircraft cannot reach the new CRZ ALT due to performance limitations or no cruise time possible at entered CRZ ALT."It's not something I generally get (In fact never) so I think more info may be useful. Things like weight, speed, alt, stage of flight etc would be good.I think one scenario when this would happen is when max fuel and load is configured and you try FL400, but that does not appear to be your situation.

Firstly its for the 747Next initially same thought process aiming for too higher alt under the weight conditions but still refused even at 15000.Initially loaded under PMDG but changed its profile under FS loader when i changed the situation from the PMDG drop down situations.Happened 3 out of 3 attempts -will try not changing the scenario and see what happens next timeTA

Hi,UNABLE CRZ ALT means that predicted Top-OF-Descent for the flightplan, weight and cruise altitude entered is calculated to be before the Top of Climb. The vertical flight path predictor is very very accurate in this plane. Therefore :(a) Check your flightplan -- for good measure DELete dicontinuities(:( Check your flightplan altitude constraints -- some terminal procedures are completely wrong. If necessary delete one or two silly constraints.© Check your weight -- in particular check units from PMDG menu(d) Try another one.Best,Vangelis===================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com=====================================

Ok One thing I hadn't done which when trying to isolate causes was ib the route section I had not input a departure runway. After doing that on th elast occassion it worked wonderfully.Thanks for input guysAppreciate it:-jumpy:-beerchug

Weird. I have no discontinuities, and tried my weights both in kgs and lbs. Still getting the same msg.

Weird. I have no discontinuities, and tried my weights both in kgs and lbs. Still getting the same msg.

 

Thank you for using the search function to help research an issue you seem to be having.  You don't see that much, and you should be commended for taking that initiative.  You also don't usually see people reviving 9 year old threads, but I got a laugh out of it, so thanks for that as well...

 

As far as your issue goes, it's not just an issue of discontinuities, or weights; it's also related to the length of your route.  If your route it too short, given the weight of the aircraft, and several other performance factors, it may give you this message.

 

Can you provide information about your flight?

What route?  What weight?  What day did this happen and at what time (I have a program that can pull the weather for that time period)?  What Cost Index?  What aircraft?  ...and so on.

Thanks for getting back Kyle.

 

I have used a real briefing package from my company, for the 6th of June. I had to enter/ adjust the weights and the route according to the possibilities in FSX. In the load manager and PMDG options naturally.

 

What route?  EHAM-RJAA

 

What weight? EZFW 242.000 Kgs Block Fuel 140.000 Kgs

 

What day did this happen? :6 June.

 

and at what time (I have a program that can pull the weather for that time period)?  08.45 Z I have pulled the the briefing, actual flight departure in real life was 12.40 Z

 

What Cost Index?  300

 

What aircraft? PMDG B747-400

 

Ground distance 5223, air distance 5251

 

( initial) Cruise level FL310, tried reselecting 290, no avail.

 

I have a boxed version of the PMDG 744

 

 

Thanks for getting back Kyle.

 

I have used a real briefing package from my company, for the 6th of June. I had to enter/ adjust the weights and the route according to the possibilities in FSX. In the load manager and PMDG options naturally.

 

What route?  EHAM-RJAA

 

What weight? EZFW 242.000 Kgs Block Fuel 140.000 Kgs

 

What day did this happen? :6 June.

 

and at what time (I have a program that can pull the weather for that time period)?  08.45 Z I have pulled the the briefing, actual flight departure in real life was 12.40 Z

 

What Cost Index?  300

 

What aircraft? PMDG B747-400

 

Ground distance 5223, air distance 5251

 

( initial) Cruise level FL310, tried reselecting 290, no avail.

 

I have a boxed version of the PMDG 744

 

 

"UNABLE CRZ ALTITUDE"

 

Causing Condition

FMC predicts aircraft cannot reach the new CRZ ALT due to performance limitations or no cruise time possible at entered CRTZ ALT.

 

Correct Action

Clear message and review CRZ ALT selection. Enter aircraft altitude or lower. FMC will not recognize descent phase until cruise phase is attained.

 

- In other words, your Top of Climb (TOC) is beyond the Top of Decent (TOD) ; how are you able to reach that point if you had to decent? And thus your aircraft is not able to reach that specific value of altitude. Just decrease it until you do not get that message or just check your FMC info, it will come with a recommendation for your CRZ ALT. 

I just tried your settings   and had no issues using fl310,  max fl was 348 with the settings

 

 

I have a boxed version of the PMDG 744

 

I'm wondering if you need the update available at PMDG?

http://precisionmanuals.com/pages/downloads/updates.html

 

Mike

Thanks Mike, but it tells me when I try to install it that I have the latest version already. It was worth the check though.

I have submitted a ticket @ the guys  PMDG. See what they come up with.

Weird thing is that I used to fly this same 747 on this same pc without any issues whatsoever.

Until I had to reinstall Windows 7 and everything again after a crash..