March 30, 2012

Eurocontrol has announced that all aircraft equipped with TCAS II version 7.0 must upgrade to version 7.1 by December 1, 2015 to conduct flights in European airspace. Aircraft manufactured after March 1, 2012, must now be equipped with version 7.1 A regulatory decision regarding implementation was published in the Official Journal of the European Union December 20, 2011.

The development of version 7.1 was initiated by Eurocontrol following the discovery of two safety issues with the current TCAS II version.

Version 7.1 is fully compatible with all existing TCAS versions being used today.

Version 7.1 Changes

Before conducing a flight in an aircraft equipped with version 7.1, operators should review the key changes designed to enhance safety.

Problems with Adjust Vertical Speed RA

The major change with version 7.1 is a modification to the “Adjust vertical speed, adjust” resolution advisory (RA). Eurocontrol found that pilots were confused by this RA and often increased their vertical speed rather than decreasing it as required. With version 7.1, that RA has been replaced with a new “Level off, level off” RA that is designed to eliminate any confusion.

Problems with Reversal Logic

The design of the current TCAS II version 7.0 allows for reversal RAs (i.e. “Climb, climb NOW” and “Descend, descend NOW”) to be issued when the current RA is no longer predicted to provide sufficient vertical spacing. However, there have been situations where version 7.0 failed to reverse an RA when two converging aircraft remained within 100 feet.

A feature has been added in version 7.1 which monitors RA compliance in coordinated encounters (i.e. when both aircraft are TCAS II equipped). When version 7.1 detects that an aircraft is not responding correctly to an RA, it will issue a reversal RA to the aircraft which maneuvers in accordance with the RA.

Version 7.1 Resources