Honeywell developed the first ground proximity warning system (GPWS) in the 1970s and introduced the enhanced ground proximity warning system (EGPWS) in 1996.
EGPWS serves as an independent monitor of an aircraft's position relative to surrounding terrain, providing aircraft with worldwide protection against controlled flight into terrain (CFIT), windshear and optional runway incursions/overruns.
Since its inception, Honeywell has been constantly evolving its EGPWS algorithms, based on improved mapping and position technology and practical real-world experience.
As an example, following a National Transportation Safety Board (NTSB) investigation of FedEx flight 1478 which crashed on approach to Tallahassee Regional Airport in July 2002, a number of enhancements to the EGPWS algorithms were implemented and have been available since 2003.
Unfortunately, airlines and other operators have not always availed themselves of the software updates, which has contributed to accidents that may have been preventable—most recently, a fatal CFIT accident of United Parcel Service flight 1354 in which the Airbus A300 crashed on a non-precision approach to a runway in Birmingham, Alabama.
At the time of the crash, there were 15 newer versions of EGPWS software available. As noted in the NTSB report on this accident, Honeywell software that offered enhanced alerting had been available since December 2003 but was not installed in this aircraft.
As a result of this accident, in March 2015 the Federal Aviation Administration (FAA) issued a Special Airworthiness Information Bulletin (NM-15-11) advising operators of potential safety improvements.
The NTSB found that the EGPWS software operated per its design during the flight. However, if the airplane had been equipped with the later version of EGPWS software available, the caution alert the flight crew received would have sounded about 6.5 seconds earlier, at 150 feet higher.
In its Special Airworthiness Information Bulletin, the FAA stated: “Although it is not clear if the later version of the software would have prevented the accident, it would have provided a significantly improved margin of safety.”
The latest enhancements bring terrain awareness alerts significantly closer to the runway—as close as 0.25 nm with GPS input.
Honeywell recently followed up on the NTSB report with a detailed Service Information Letter (SIL D201504000056), available at the MyAerospace portal under the Technical Services tab.
The June 2015 SIL is applicable to MK V, MK VI, MK VII, and MK VIII models of EGPWS installed in fixed wing aircraft as well as the enhanced ground proximity warning module (EGPWM) found in Primus Epic aircraft manufactured by Cessna and Dassault.
Any operator who needs further clarification about the enhancements or applicability to their aircraft can contact email@example.com.