an MSAW alert indicates the existence of an unsafe situation. The Safety Board concludes that 64 seconds would have been sufficient time for the CERAP controller to notify the Agana tower controller of the low-altitude alert, the tower controller to convey the alert to the crew of flight 801, and the crew to take appropriate action to avoid the accident.
Because of its periodic evaluations of air traffic facilities, FAA quality assurance staff knew as early as July 1995 that the Guam ARTS IIA MSAW system had been inhibited. The inhibition was cited in a 1995 FAA facility evaluation report but was only classified as an "informational" item. The FAA conducted no followup activities after the 1995 evaluation to determine whether corrective action had been taken to restore the MSAW system to the full service for which it was designed. In April 1997, the FAA conducted a second evaluation of the Guam facility, but the FAA's report on this evaluation did not even note that the ARTS IIA MSAW system was inhibited. Thus, the FAA missed two opportunities not only to recognize that the MSAW system was inhibited to the extent that it was rendered almost completely useless but also to take corrective action. An appropriate corrective action could have prevented this accident. Therefore, the Safety Board concludes that the FAA's quality assurance for the MSAW system was inadequate, and the agency's intentional inhibition of that system contributed to the flight 801 accident.
As previously noted, in this accident there would have been sufficient time (64 seconds), if the MSAW system had generated an alert in the CERAP facility, for the CERAP controller to have relayed the information to the tower controller. However, under different circumstances, an aircraft descending below the minimum safe altitude may not generate an MSAW alert as far in advance, so controllers may have significantly less time to react. In those cases, it would make a critical difference if the MSAW alert were provided directly to the airport tower.
The Safety Board has long been concerned about the issue of aural MSAW alerts in towers. As part of its investigation into the January 1995 Beechcraft A36 accident, the Safety Board found that the FAA did not have a policy regarding the installation of an aural MSAW alert at low-density ATC towers equipped with D-BRITE radar displays. As a result, the Safety Board issued Safety Recommendation A-95-120 on November 30, 1995. Safety Recommendation A-95-120 asked the FAA to develop a policy that would require the installation of aural MSAW equipment in those visual flight rules (VFR) terminal facilities that receive radar information from a host radar control facility and would otherwise receive only a visual MSAW alert.[1]
In June 1996, the FAA stated that it was feasible to install the aural MSAW alert in 112 VFR towers. In July 1997, the FAA stated that 69 of 112 ATC facilities did not have remote displays with aural alarms and that aural alarms at these facilities would be installed by February 1998. In May 1998, the FAA stated that the aural alarms at these 69 remote sites would be operational by the end of that month. However, in March 1998, at the Safety Board's public hearing, the FAA's Deputy Program Director for Air Traffic
- ↑ For more information on this safety recommendation, see section 1.18.2.2.
