The cabin pressure controllers use ambient pressure and flight plan data from the FMC to calculate a cabin pressurization schedule. The schedule provides a comfortable cabin climb to cruise altitude. For takeoff, the system provides a small positive pressurization prior to rotation to cause a smooth transition to the cabin altitude climb schedule. During climb, cabin altitude increases on a schedule related to airplane climb rate and flight plan cruise altitude. When the FMC climb path has a planned level segment, it is included in the total time required for the airplane to reach the top of climb and cabin altitude continues to increase during the level segment. If the airplane climb flight path is above the FMC climb path and maximum cabin pressure differential is reached during the climb, cabin rate then becomes a function of airplane climb rate so maximum cabin differential pressure is not exceeded.This is the key excerpt from Boeing's 744's Operations Manual on the subject of pressurization "schedule". No more insight is offered, no graphs nor tables. I don't think any programmer would consider the above information sufficient to develop complete algorithm. This is a very good illustration to some past discussion on this forum whether having access to 1000-page aircraft manual is enough in developing credible simulation.Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2

Michael-we have a "wee bit more" info than that :-).