The security system provides an aircraft security system capable of protecting both single and multiple engine aircraft. The air conditioner includes two or more heat exchangers, a refrigerant pipe, a compressor, an accumulator, and an overcooler. The transistor is interposed over its source-drain line between a first resistive load included in a RC network creating a zero in the open loop gain of the regulator, and a second resistive load to produce a drive signal for the output stage of the regulator. The method also includes providing at least one of a copy of the iTIP message and a copy of the iMIP message to a least one of the second client device and a second communication server device connected to the second client device for enabling the second calendar application to generate a calendar entry in the second client device.