UPS says it is “evaluating an upgrade” to the software of its enhanced ground proximity warning system as a result of the A300-600 crash in Birmingham on August 14. The action, along with nine other “post-accident safety initiatives and enhancements”, are included in a new report the carrier filed with the NTSB as part of the ongoing Flight 1354 investigation.

In the submission,  dated May 1 and made public this week, UPS says the pilots were task-saturated and lost situational awareness which, when combined with not following standard operating procedures, caused a controlled flight into terrain accident in night, instrument conditions. Airbus, in its submission to the NTSB, similarly blames the pilots for failing to conduct and monitor the approach, including vertical descent rates, and for not performing a go-around either at the minimum altitude for the non-precision approach, or when the aircraftjavascript:void(0);’s Honeywell-built enhanced ground proximity warning system (EGPWS) issued a “sink rate” alert.
 
The captain did reduce the vertical descent speed from -1,500 ft/min to -600 ft/min after receiving the “sink rate” caution (the system issues an audible message when the descent rate is more than 1,000 ft/min during that portion of the approach), but continued the approach rather than performing a go-around, per UPS’s stabilized approach criteria.
 
An EGPWS “too low terrain” alert that sounded 9 sec. after the sink rate alert is the topic of much debate. The alert, part of flight management system-based terrain protection feature of EGPWS, activates when an aircraft descends below a certain altitude above terrain during an approach, assuming a 3-deg. glideslope. The software version onboard Flight 1354 did provide that function, but not until 1 sec. after the aircraft had hit trees on the approach.

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 FAA 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.