GPS-Based Monitoring System (GMS)


The Enhanced GPS-based Monitoring Unit (EGMU)

The EGMU contains a GPS receiver, two portable shielded GPS antennas, and an Altitude Recording Device (ARD) to capture Mode-C data emitted by the aircraft's transponder. It is noted that these components are contained within a case that meets airline standards for carry-on luggage. 

Components of the GMU include:

  • GPS Receiver
  • Two portable shielded GPS antennas
  • Internal battery operation, no external power required
  • Case for storage of components

Altitude Recording Device (ARD pictured) option for collecting Mode C data for analysis for flights outside of USA.

The EGMU case and components meet the airline standard for carry-on luggage.

EGMU Monitoring

The EGMU supports the FAAs GPS-Based Monitoring System (GMS) by providing an on-demand means for operators to satisfy their RVSM monitoring requirements and is rapidly and transparently installed onboard aircraft without impact to aircraft systems and flight crews in the performance of their duties. Typical installation of the EGMU requires a set up time of less than 15 minutes to temporarily install the equipment and place GPS antennas in the cabin or aft cockpit windows to permit data collection. The EGMU and its components are battery powered. Once installed, the monitoring specialist will work with the flight crew to capture specific information in the Flight Information Form (FIF) relating to the monitoring flight.

Monitoring Flight Options/Procedures

Monitoring may be conducted on scheduled, ferry, or special test flights. The goal of monitoring is to collect a GPS data file during straight and level phases of flight while within the RVSM stratum (FL 290-410 inclusive) for approximately 30 minutes. The FAA has selected CSSI, Inc. to serve as a monitoring service provider on behalf of RVSM airspace users. Specialists from CSSI routinely conduct monitoring flights after an operator has developed a schedule with our operations coordinator. Upon completion of a monitoring flight, CSSI performs the initial post-flight processing of the data which is then transmitted to the FAA for further processing to calculate the aircraft's altimetry system error (ASE) with the results provided to the operator's State authority.

For specific questions or additional information please contact a RVSM Team Member.