Trans States Airlines Flight 3395

After receiving intermittent localizer indications on the airplane’s first approach to the airport, the flight crew, conducted a go-around, and air traffic control cleared the flight for a second approach. The captain indicated that, while the airplane was level at about 2,000 ft on the base leg, the flight entered clouds. The first officer stated that she noted moisture on the windshield wiper and the captain indicated that the wind screen was wet. The cockpit voice recorder (CVR) recorded the captain and first officer briefly discussing ice; however, the airplane’s ice protection system, which was set to the automatic mode, did not operate automatically, and the crew did not activate the system manually. The crew did not see the ice light come on and there were no icing messages on the engine indicating and crew alerting system. As the first officer was applying control inputs to adjust for a crosswind, a rapid roll to the right occurred, which resulted in a wing strike and substantial damage to the airplane. About forty minutes after arrival at the gate, an examination of the airplane found an accretion of ice on the leading edge of both wings. The aircraft performance study, which correlated icing charts with the airplane’s flight profile, determined that the airplane spent over 20 minutes at altitudes where icing was probable during both approaches. The study concluded that the right roll was not commanded by the flight crew but likely due to ice buildup. Although the vertical load factor did not indicate that the airplane experienced a full aerodynamic stall, the ice buildup likely created enough flow separation on one wing for it to lose lift during the flare, without affecting the control of the aircraft in a measurable way during the approach. After the accident, the ice detection and anti-ice systems were tested at the aircraft level with no anomalies identified. The ice detectors were also functionally tested by the manufacturer at the component level with no anomalies identified that could have contributed to the event. A review of FDR data revealed that no failures were recorded for the ice detection system during the accident flight. Additionally, the system operated as expected during a manual preflight test and detected icing conditions during the previous flight. A review of the maintenance records did not reveal any systematic problems with the ice detection system. Therefore, it could not be determined why the ice detection system did not detect the presence of icing conditions even though the airplane accreted ice during the approach. This possibly could have been due to variations in static air temperature that prevented the ice that accumulated on the sensors from reaching the alert threshold or the occurrence of meteorological conditions out of the 14 Code of Federal Regulations Part 25 Appendix C during approach, or a combination of these two factors.” Although the ice detection system did not automatically activate the ice protection system, the CVR recorded a brief discussion during the final approach indicating that the crew was aware that the airplane was picking up “a little bit” of ice. According to the Trans States Airlines EMB145 Airplane Operations Manual (AOM) and Standard Operating Procedures (SOP), even though the airplane is equipped with an ice detector, the crew was responsible for monitoring icing conditions and for manual activation of the ice protection system when necessary. Therefore, the crew recognized that the airplane was operating in icing conditions and accumulating ice and should have manually activated the ice protection system. It is likely the crew's overreliance on automation for the activation and proper operation of the ice and rain protection system resulted in their failure to adequately monitor the system and respond appropriately when it did not activate automatically. Although the AOM and SOPs indicated that the crew is responsible for monitoring icing conditions and for manual activation of the ice protection system when necessary, there was no information in Trans States Airlines ground training modules that presented the crew as being responsible for monitoring and activating the ice and rain protection system when no warnings or cautions were received from the EICAS. Additionally, manual ice detection methods for flight crews to use when flying in potential icing conditions were not specifically referenced during ground training. The Trans States Airlines manager of flight standards said that manual selection of the anti-ice system was not emphasized in training like the automatic mode of operation was during flight operations. It is possible that because the manual operation of the airplane's ice protection system was not emphasized during training, the crew may not have recognized the need to perform this task. Trans States Airlines issued an operations bulletin after the accident that stated interim procedures for crewmembers to follow when operating in potential in-flight icing conditions. The bulletin called for active monitoring of the deicing/anti-icing equipment and, if it did not activate, to accomplish the QRH's Ice Detectors Fail procedures.

Verbatim NTSB analysis and probable cause from the NTSB dataset