– 16 –
– Airspeed, Altitude, and Rate of Sink – at 500 feet AFL (primarily for instrument cross-check).
– Rate of Sink – any time it exceeds 700 feet per minute when altitude is below 500 feet AFL and always from runway threshold to point of touchdown. Additionally, during the instrument approaches, call out:
– Altitude – when minimum authorized altitude is reached. The F/E will monitor instruments, and assist pilots in maintaining a "watch" for traffic or other factors that could adversely affect safety."
N1996 was equipped with a rain repellent system designed to keep the windshield free of water distortion and provide forward visibility from the cockpit during in-flight rain conditions. This system utilizes nozzles located in the lower center corner of the pilot's and copilot's windshield which, when activated, directs repellent fluid over the selected windshield. The repellent is spread over the windshield by the windshield wipers and by airstream and water flow outside of the wiper areas. Because the water flow over the windshield acts as an aid in spreading the repellent and in eliminating the possibility of fluid residue obscuration on the windshield, it is recommended that the system be utilized only in moderate to heavy rain conditions. This system is designed for use, with the same effectiveness, during either day or night operations. American Airlines operating procedures recommend that the repellent be used on only one windshield at a time, normally on the windshield of the pilot not flying the aircraft. It is also recommended that the repellent be used in conjunction with the wipers and not used in light rain conditions.
During the investigation of this accident a Flight Control and Performance Characteristics Group was organized: (1) to review the flight recorder data and derive the maximum technical information available from the readout (see Section 1.11 Flight Recorder), (2) to review the basic airworthiness requirements and low speed performance and flight characteristics of B-727. (3) to examine and/or develop all applicable aerodynamic-type data which would be useful in the investigation, and (4) to review the B-727 flight crew training programs with regard to information disseminated to the crews relating to flight characteristics of the aircraft.
This group was formed in light of another recent and generally similar Boeing 727 accident and following the suggestion that there might be some inherent design characteristic of the aircraft that might be in some way related to the cause of these accidents. This group was later expanded to encompass a subsequent Boeing 727 accident.
The entire study disclosed no evidence of any design or performance deficiency and substantiated that the FAA and the Boeing Company had conducted extensive tests and research to validate and insure that the Boeing 727 complied with all applicable Federal Aviation regulations.
Examination of the Boeing 727 technical data revealed that the two design features which serve to distinguish it from other jet transports were its three-engine configuration and sophisticated wing flap or high lift system. These unique features of the 727 design were explored thoroughly by the FAA during type certification and it was found that the performance and flight characteristics were in conformance with the design criteria and all applicable certification requirements.
