FAA Warns of Spurious TCAS Resolution Alerts

The FAA released Information for Operators bulletin 15005 last week that warns pilots of "potential spurious" Tcas resolution alerts (RAs) aboard aircraft equipped with Honeywell TPA-100B Tcas II version 7.1 RTCA/DO300-compliant hybrid surveillance units. Several spurious RAs have been reported by air navigation service providers in European airspace, but to date there have been no reported cases in U.S. airspace.

However, the FAA said operators of Tcas II version 7.1 RTCA/DO300-compliant hybrid surveillance units, regardless of equipment manufacturer or aircraft type, could be affected by spurious RAs. Research data suggests the spurious RAs are generated only when another aircraft crosses between five to seven nautical miles from behind. In all reported cases, there has been no reduction of horizontal separation or possible risk of collision between the two aircraft at the time of the RA. Pilots are reminded to continue to follow existing approved procedures when any RA occurs.