Hi All If you're planning on flying a 737 for IYP Air, My advice to you is execute the pre-flight checklist at the last possible moment, to prevent the battery from running out before you've had a chance to start the engines. I added the line MagicBattery=Yes to FSUIPC4.INI, within the General section, and this made no difference. If anyone has successfully added this switch, I'd be delighted to hear about it. I would have thought that FSX would allow the APU to keep things alive before the engines are started, but no. T