The height monitoring process for HMU is as follows:

Monitoring Hours

All the HMUs measure automatically every overflight within its coverage in 24H and 7 days basis except periodic maintenance and unexpected technical problems. Usually, no special procedure is required by the operator, however, check the HMU Status Information in advance.
Location of HMUs in Japan

Coordination of the flight to receive the height monitoring service

For tailored flight planning to receive the height monitoring service, prior coordination with the Air Traffic Management Center(ATMC), the Monitoring Flight Desk, should be required by this website or an e-mail at least 7 days prior to the date of the flight.
The height monitoring procedures in Fukuoka FIR_20200521

Course and Flight Level

At least 20NM straight and level flight within the horizontal coverage and RVSM altitude band are required. Pilots should not solicit a haphazard height monitoring in flight due to an impact on the ATC workload. Prior coordination for a height monitoring should be addressed to the Air Traffic Management Center as shown above.


The summary of the successful measurement results will be shown in the “HMU” – “Result” page in about 4 weeks. If the measurement result of a specific aircraft shows deterioration in height keeping performance, the report to ask an improvement of height keeping performance is made to the operator or the other RMA, in accordance with “The operating procedure for the safety assessment of the RVSM airspaces and the height keeping performance monitoring” ( Japanese : ) 4.2. and 5.2.2. established by Japan Civil Aviation Bureau.

・By flying over either Setouchi, Niigata, or Sendai HMU at RVSM flight level band, the height monitoring is conducted automatically for height keeping accuracy to be measured.
・In an adverse weather condition, there may be a case where the measuring accuracy may not be accurate enough hence nullifying the measurement result.
・Separation setting has precedence and, if necessary, altitude change and/or changing flight direction may be instructed, thus canceling the measurement.

For further information

If you have any questions about height monitoring, please contact us. See the “Contact Us” page.