About RVSM Safety

As part of the RMA duties and responsibility, the MAAR conducts periodic safety assessments, now called safety oversights, to ensure that the RVSM implementation in the Asia Region continues to be safe. This includes:

  • assessing the overall risk (technical combined with operational and in-flight contingencies) in the system against the overall safety objectives,
  • initiating checks on the approval status of aircraft operating in the relevant RVSM airspace,
  • identifying non-approved operators and aircraft using RVSM airspace and notify the appropriate State of Registry/State of the Operator accordingly.

In addition, three primary objectives need to be achieved in terms of RVSM height monitoring:

  • Compliance with the Annex 6 requirements for long term height-keeping monitoring through the globally standardised Minimum Monitoring Requirement (MMR - e.g. two aircraft per type, per operator, per two years),
  • Conduct of analyses of aircraft group performance, and
  • Evaluation of the stability of altimetry system error.

Safety Objectives

Safety objectives for RVSM implementation and operation have been set for both technical risk and overall risk and are as follows.

Type Due to Does not exceed
Technical risk aircraft height-keeping performance 2.5 fatal accidents
per 109 flying hours
Overall risk all causes, including the technical risk and all risk due to operational errors and in-flight contingencies, such as but not limited to pilot/controller errors, height deviations due to emergency procedures, and turbulence 5 fatal accidents
per 109 flying hours

To be able to estimate parameters for the Collision Risk Model (CRM), MAAR needs Large Height Deviation (LHD) reports and annual Traffic Sample Data (TSD) from States. (See Responsibilities of States.)

How Risk Is Estimated

The following diagram shows an overview of the risk estimation process. The risk assessment is performed based the Collision Risk Model (CRM). There are many assumptions that are used in the calculation, one of which is that 'no reduction is risk is attributed to collision avoidance systems or evasive action on the basis of visual guidance'.

Each year's risk values are calculated based on December traffic data and Large Height Deviation (LHD) reports throughout the year. The risk assessment's results of the most recent year are summarized here.

LHDs are extremely influential to the risk values. Learn more about LHDs here.

Risk estimation process