NG tyhle prepiance uz nemaji, tak sem tohle sem nasel pres google, je to vynatek z operacnich poznamek US Airways:
During ground operation the aircraft will be depressurized until the GRD/FLT switch is selected to FLT after engine start. The cabin will then automatically drive to 200 ft. below ambient pressure (.1 psi). After takeoff the pressurization controller will climb the cabin proportional to the aircraft climb rate on schedule up to a max of 500 fpm. When within about 1000 ft. of the set cruise altitude (FLT ALT) the controller will then trip a relay and enter a cruise mode and will maintain a constant cabin altitude with either a differential of 7.45 (below FL 280) psi or 7.80 psi (FL 280 and above). During cruise mode the controller will allow minor fluctuations in the differential up to 7.90 psi to maintain a constant cabin altitude. When descent is begun to about 1000 ft. below cruise altitude a descent relay trips and the controller will program cabin descent down to selected LAND ALT at max rate of no more than 350 fpm. The controller will actually descend the cabin to 200 ft. below the set LAND ALT to allow the aircraft to land slightly pressurized, just as in takeoff. During taxi in the FLT/GRD switch will be positioned to GRD which will then allow the aircraft to be fully depressurized.
Jendoduse receno, pokud das do polohy GRD, ero bude "depresurized", jakmile zavres dvere a si nekde na pojizdeni, das FLT coz ero natlakuje na nejaky pocatecni tlak vhodny pro zahajeni letu (200ft).
