I have set the cargo to be 14949kg and Topcat states that the payload dis should be 7159/7790. However the FMC will not let me enter those values.

Are TOPCAT and the FMC using the same units? KGS or LBS?

 

Otherwise, you may just be overweight. I know TOPCAT uses different weight for passengers and baggage than the NGX. Not quite sure what PMDG used. I never really bothered to edit the TOPCAT .ini file to make them match.

If I may say - you are making life more complicated that it need be.

 

Use the PMDG Payload & Fuel functions inside the CDU to set what you require...this will give you the Planned Taxi Weight - then subtract from this the fuel you will use getting the the RWY (12 mins & 150 - 250kgs is a good starting point) - this then gives you your Planned Take Off Weight (PTOW).

 

Go straight to the Take Off Page (TOPCAT)

 

Enter your PTOW in the box provided (also obviously populating the ARPT/RWY/INTERSECTION/WX fields as you go)

 

Select any performance limiting factors like Flap Setting/THRUST RATING etc

 

Then let TOPCAT Calculate your numbers from there.

 

STAB TRIM will come from the FMC once the CDU preflight is complete.

 

IRL the PTOW is the only number any 'onboard' software based take off calculation tool is really interested in.

Hi.

 

If you read this topic you  may find an answer to your question. We were discussing a lot of questions regarding TOPCAT. I did some chabges to TOPCAT and I am finally happy. My NG and TOPCAT talk to each other very well.

 

http://forum.avsim.net/topic/391764-topcat-configuration-for-pmdg-738ngx/