Software errors have been found and corrected on the minimum-safe-altitude warning (MSAW) systems at three US airports, the US Federal Aviation Administration has revealed. The MSAW alerts air-traffic controllers when an aircraft equipped with a Mode C transponder descends below minimum safe altitude during a landing approach.
The inspection of 191 MSAW functions in the USA was ordered after it was discovered that the system operating on Guam was not working properly at the time of the 6 August Korean Air (KAL) Boeing 747-300 crash during a non-precision bad-weather approach to Guam's Agana International Airport.
US accident investigators say that the faulty MSAW did not cause the crash, but could have helped prevent it. The software error - now corrected - was introduced when the MSAW function was modified to curtail false alarms.
During testing, FAA technicians found software errors in the MSAW functions in Fayetteville, North Carolina, and Florence, South Carolina. These have been corrected, and the FAA says that the faults had not caused any known incidents.
Source: Flight International
