A more recent GPS-based version of the terrain protection feature would have sounded the “too low terrain” warning 2.5 sec. after the “sink rate” message, while the aircraft was 156 ft. above the terrain, according to an Airbus analysis. In a simulator session with UPS pilots and others in Toulouse, Airbus found that an automatic or manual go-around maneuver initiated 1.5 sec. after the “too low terrain” alert from an upgraded EGPWS “would provide sufficient altitude to clear the obstacles.” Airbus had been promoting the upgrade with operators through publications and meetings since 2006, including at an A300/A310 family operational liaison meeting in Louisville, UPS’s home base, in 2006.
UPS in its submission says the newer version of the software “may provide enhanced safety,” but noted that the installed version met all requirements. “In this instance, UPS does not believe the updated software would have been sufficient to prevent this accident.” Its reasoning in part comes from the categorization by Airbus and Honeywell of the “too low terrain” alert as an EGPWS “caution alert”, which does not require immediate action, as opposed to a “warning alert,” which does.
Other initiatives UPS is considering include modifying required pilots callouts on an approach to include stabilized approach criteria, emphasizing the connections between EGPWS and stabilized approach criteria and evaluating changes to how pilots react to EGPWS alert responses.