execution of nonprecision approaches was ineffective, which contributed to the deficient performance of the flight crew.
In addition, on the basis of the history of similar accidents involving U.S. air carriers, the Safety Board concludes that U.S. air carrier pilots would benefit from additional training and practice in nonprecision approaches during line operations (in daytime visual conditions in which such a practice would not add a risk factor). Therefore, the Safety Board believes that the FAA should issue guidance to air carriers to ensure that pilots periodically perform nonprecision approaches during line operations in daytime visual conditions in which such practice would not add a risk factor.
2.6 Air Traffic Control Factors
2.6.1 Controller Performance
Safety Board investigators evaluated the performance of the CERAP and Agana tower controllers to determine whether their performance played a role in the circumstances of the accident. FAA Order 7110.65, "Air Traffic Control," prescribes the ATC procedures that controllers are required to follow. The investigation revealed three deviations from those procedures on the part of the CERAP controller.
The CERAP controller failed to provide the flight crew with a position advisory relative to a fix on the final approach course when he cleared flight 801 for the approach. If such a position advisory had been given, as required by paragraph 5-9-4, the pilots might have been prompted to cross-check their radar position with the cockpit DME and other navigational aid indications, thereby improving their situational awareness. In addition, the CERAP controller did not inform the flight crew or the tower controller that he had observed a rain shower (described by the CERAP controller as a "cell" during a postaccident interview with Safety Board investigators) on the final approach path, as required by paragraph 2-6-4. Although the pilots should have been aware of the weather situation because they were using on-board weather radar, their decision-making might have been aided if the CERAP controller had provided his weather observations.
The CERAP controller also failed to monitor the flight after the frequency change to the tower controller.[1] As a result, the CERAP controller did not immediately recognize that the airplane was overdue. (Paragraph 10-3-1 states that a controller who has any reason to believe that an aircraft is overdue should immediately take appropriate action.) If the CERAP controller had been properly monitoring the flight on one or both of the radar displays he had available to him (the en route display and/or the terminal display), he might have observed flight 801 disappear on final approach. Also, the controller might have noticed the approach path warning (low-altitude MSAW alert) that was generated on the en route radar display,[2] which began about 6 seconds before impact
- ↑ 211 The controller was required to continue monitoring the flight because radar service had not been terminated in accordance with paragraph 5-1-13.
- ↑ The CERAP controller was monitoring the EARTS (en route) radar scope, which had a functioning MSAW capability. However, this MSAW capability was based on a different algorithm than the disabled ARTS IIA MSAW system (see section 2.6.2). The ARTS IIA MSAW system compares the airplane's trajectory with the ILS glideslope. The EARTS system uses a single altitude (based on the lowest MDA for all nonprecision approaches to the runway) from the FAF to the point at which MSAW processing terminates (usually 1 mile from the runway threshold).
