Monitoring and ReportingOccurrences of Large Height Deviations

       Why CollectLarge Height Deviation Report?

       An RMA must be prepared to collect the information necessary to assess the in-service technical heightkeepingperformance of the aircraft operating in the airspace for which it has monitoring responsibility. In addition, itmust establish procedures for the collection of information concerning large deviations from the cleared flight level andoperational errors caused by non-compliance with ATC instructions or loop errors within the ATC system.

       Definition and Cause of LHD event

       A RVSM large height deviation (LHD) is defined as any vertical deviation of 90 meters/300 feet or more from the flight level expected to be occupied by the flight.

        It is necessary todistinguish events caused by operational errors during the RVSM safety assessment. It is necessary to clear LHD taxonomy. In addition, China RMA should share LHD data with other RMAs.

       The causes of a LHD occurrence include:

       1. Operational errors refer to human factors issues during the flight (including incorrect flight level, coordination errors in the ATC to ATC transfer or control responsibility)

       2. Aircraft contingency events and LHD events due to cannot implement normal emergency measures result in compelled climbing/descending or cross flight level.

       3. Deviation due to weather related cause.

       4. Deviation due to TCAS.

       5. An aircraft being provided with RVSM separation is not RVSM approved.

       ICAO has provided detailed classification about LHD events causes. China RMA also published a poster of“Definition and Classification of LHD Events”, which gives detail of definition and classification of LHD events to help controllers and flight crew to identifyand report LHDs.

       LHD Reporting Mechanism

       Since 2007, China RMA has established the mechanism of LHD reporting mechanism over all en-route ATC departments, and the frequency of reporting is on a monthly basis. The should controllers identify and confirm LHD occurrences during their daily work and report to their supervisors, after confirmation the detail of the event are reported to the point of contact of the responsible regional ATMB, who will then fill in the ATC LHD reporting template and submit reports to China RMA through the ‘China RMA Data Exchange Platform’.

Figure 1theMeeting of Establishing ATC LHD Reporting Mechanism in Haikou, 2007

             China RMA has established the mechanism of LHD reportingfromoperatorsin 2010, and the reporting frequency is also on a monthly basis. Pilotsshouldidentify and confirm LHD occurrences during their flight and report to their supervisors, after confirmation the detail of the event are reported to the point of contact of the operator, who will then fill in the Pilot LHD reporting template and submit reports to China RMA through the ‘China RMA Data Exchange Platform’.