Many parameters are available from Mode S, ADS-B UAT (Universal Access Transceiver) and ADS-B ES (Extended Squitter) i.e. (Mach number, indicated airspeed, vertical speed, heading etc.) There are no provisions about how or if there a need to check them for validity. Mode C for example is supposed to be checked when the aircraft is identified for the first time but there is nothing in ICAO documents about other data.

IFATCA Policy is:

Altimeter Setting Monitoring Tool (ASMT)

  • ATM systems shall have a tool which provides a warning to controllers, if there is a discrepancy between aircraft altimeter setting and appropriate altimeter setting.
  • Implementation shall include appropriate operational requirements, procedures and training to respond to such a warning.

When using downlinked Altitude (PSA):

  • It shall not be used to provide separation;
  • The display of a PSA should not be used as a substitute for a readback;
  • An alert should be presented to the controller for aircraft with a mismatch between PSA and the Cleared Flight Level (CFL);
  • Nuisance alerts should be kept to a minimum;
  • An alert timeout period should be applied to allow for a new level to be selected in the cockpit.
See: Resolution B4 – WP92 – Conchal 2019, WP95 – Abu Dhabi 2025

 

Last Update: 29th December 2025
3rd November 2019 987 Jean-Francois LepageAASSurveillance , TOC , AAS , TPM , ATM Operations

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