AEROTHAI provides the HKP monitoring service using a portable GPS-based Monitoring System (GMS). AEROTHAI uses an Enhanced GPS-based Monitoring Unit (EGMU) to collect (1) GPS data and (2) pressure altitude or Mode C data during a monitoring flight.

As shown in Figure A, the EGMU is a portable unit composed of a Global Positioning System (GPS) receiver and the Altitude Recording Device (ARD), two GPS antennas and one ARD antenna (temporarily mounted on interior windows with suction cups).

Figure A: EGMU Components

The equipment can be installed in the aircraft cockpit or cabin, depending upon the aircraft type. The installation takes approximately 30 minutes and is best suited on the aft cockpit windows. EGMU installation and operation will not interfere with crew operations. The example of EGMU installation is given in Figure B.

Figure B: Example of EGMU installation on Beechcraft King Air

The HKP monitoring can be conducted on scheduled flights, ferry flights, or monitoring-specific flights. To ensure collection of sufficient position data, the aircraft must fly at a single altitude from FL290 to FL410 for at least 40 minutes in a Mode-C radar coverage area.

After completion of the monitoring flight, the collected data will be processed to determine the aircraft’s ASE. Final ASE results should be available within four to eight weeks of the monitoring flight. The official monitoring results will be submitted to the State Authority and a copy to the aircraft operator.