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What is correct for PDE (Path Definition Error)?
  • A
    Path defined by RNAV system does not correspond to the desired path.
  • B
    Path defined by RNAV system corresponds to the desired path.
  • C
    The RNAV calculated aircraft coordinates corresponds to the actual aircraft coordinates.
  • D
    It relates to the air crew or autopilot’s ability to follow the defined path or track.

Performance-based Navigation (PBN)

The inability to achieve the required lateral navigation accuracy may be due to navigation errors related to aircraft tracking and positioning. The three main errors in the context of on-board performance monitoring and alerting are path definition error (PDE), flight technical error (FTE), and navigation system error (NSE).

  • Path Definition Error (PDE) occurs when the path defined in the RNAV system does not correspond to the desired path, i.e. the path expected to be flown over the ground. RNAV system is unable to accurately define the desired path.
  • Flight Technical Error (FTE) relates to the air crew or autopilot’s ability to follow the defined path or track, including any display error (e.g. course deviation indicator (CDI) centring error).
  • Navigation System Error (NSE) refers to the difference between the aircraft’s estimated position and actual position. It is the error in the accuracy in determining actual aircraft coordinates.

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