Page:KAL801Finalreport.pdf/107

 a supervisor with the ability to monitor MSAW alerts immediately from every controller position that displays an alert.

On February 27, 1998, the Safety Board stated its understanding that the current STARS operational documentation contained no requirement to duplicate the MSAW alerts at supervisory positions and that STARS would provide a supervisor with the ability to monitor MSAW alerts immediately from every controller position that displays an alert. The Board explained that it was not the intent of this recommendation to have a controller workstation be designed for the supervisor but rather to enable the supervisor to be "in the loop" if an MSAW alert was generated. The Board believed that such an arrangement would serve as a form of redundancy that could enhance the benefits of the MSAW system and STARS.

In its September 25, 1998, letter, the FAA stated that supervisors should be aware whenever MSAW alerts are generated. Further, the FAA stated that, in STARS, supervisor awareness of MSAW events is accomplished through aural alarms at each controller position. According to the FAA, supervisors are expected to be on the control room floor to monitor all areas of the operation, including MSAW alerts, and are expected to spend a minimal amount of time at supervisory workstations.

On January 14, 1999, the Safety Board stated that the individual aural alert speakers located at each controller position should alert a supervisor to the sector experiencing an MSAW alert. Therefore, supervisors should be able to react to each alert from their workstation or throughout the operating floor. Because the intent of Safety Recommendation A-97-27 was satisfied in an alternative manner, it was classified "Closed--Acceptable Alternate Action."

1.18.2.1 Traditional Ground Proximity Warning System Traditional GPWS uses numerous input signals to determine if a terrain collision threat exists. Inputs from the aircraft systems include the radio altitude, descent rate and airspeed, landing gear position, landing flap position, and glideslope information. This information generates the visual and aural annunciations to the flight crew. GPWS uses the radio altimeter to calculate closure rate with terrain to predict a potential collision threat. However, if the terrain rises steeply (for example, a sheer cliff), the system cannot provide a timely warning to the flight crew. The optional altitude callout