4/26/2011 12:00 AM
On May 24, 2011, the National Transportation Safety Board held a Board Meeting to discuss and adopt the Aviation Accident Report relating to the crash of Empire Airlines Flight 8284, Lubbock, TX, January 27, 2009.
On January 27, 2009, about 0437 central standard time, an Avions de Transport Régional Aerospatiale Alenia ATR 42-320, N902FX, operating as Empire Airlines flight 8284, was on an instrument approach when it crashed short of the runway at Lubbock Preston Smith International Airport, Lubbock, Texas. The captain sustained serious injuries, and the first officer sustained minor injuries. The airplane was substantially damaged. The airplane was registered to Federal Express Corporation and operated by Empire Airlines, Inc., as a 14 Code of Federal Regulations Part 121 supplemental cargo flight. The flight departed from Fort Worth Alliance Airport, Fort Worth, Texas, about 0313. Instrument meteorological conditions prevailed, and an instrument flight rules flight plan was filed.
The National Transportation Safety Board determines that the probable cause of this accident was the flight crew's failure to monitor and maintain a minimum safe airspeed while executing an instrument approach in icing conditions, which resulted in an aerodynamic stall at low altitude. Contributing to the accident were 1) the flight crew's failure to follow published standard operating procedures in response to a flap anomaly, 2) the captain's decision to continue with the unstabilized approach, 3) the flight crew's poor crew resource management, and 4) fatigue due to the time of day in which the accident occurred and a cumulative sleep debt, which likely impaired the captain's performance.
The safety issues discussed in this report include the flight crew's actions in response to the flap anomaly, the continuation of the unstabilized approach, the dispatch of the flight into freezing drizzle conditions, the efficiency of the emergency response, and simulator-based training for pilots who fly in icing conditions. Ten safety recommendations are addressed to the Federal Aviation Administration.
- The captain and the first officer were certificated in accordance with Federal regulations and were current and qualified in accordance with Empire Airlines' training requirements. The investigation found no evidence that the pilots' performance was affected by any behavioral or medical condition, or by the use of alcohol or drugs.
- The airplane was loaded within weight and center of gravity limits and was maintained in accordance with 14 Code of Federal Regulations Part 121.
- The investigation found no evidence that indicated any mechanical anomaly with the engines, and flight data recorder data indicated that the engines' performance was consistent with normal operations.
- Performance data indicated that, when the flight crew commanded 15° flaps, a flap asymmetry occurred with the left flaps extending 8° to 10° and the right flaps not extending. The data further indicated that the flaps returned to a symmetric state (about 4.5°) about 25 seconds before ground impact.
- Because of the extent of the impact and postaccident fire damage to the right flaps and flap actuators, the reason for the airplane's flap asymmetry could not be determined.
- The airplane was controllable with the flap asymmetry and airframe ice contamination and could have been maneuvered and landed safely if the appropriate airspeed had been maintained.
- The captain's failure to immediately respond to the aural stall warning, the stick shaker, and the terrain awareness and warning system warning resulted in his inability to arrest the airplane's descent and avoid impact with the ground.
- The captain was adequately trained on how to respond to flap anomalies, and the captain's statement that the airplane had "no flaps" indicates that he had sufficient information to recognize that he should immediately perform a go around maneuver and apply the appropriate procedure from the quick reference handbook that applied to all flap problems.
- Although the captain indicated that he was concerned about the icing conditions, the presence of airframe ice accretion within the capabilities of the airplane's systems does not negate the importance of adhering to standard operating procedures and performing a go-around maneuver to respond to the multiple cues associated with an unstabilized approach including excessive deviation from the glidepath, sink rate greater than 1,000 feet per minute, and airspeed less than the required approach speed.
- Had the captain complied with standard operating procedures in response to the flap anomaly, unstabilized approach, stick shaker, and terrain awareness and warning system warning and initiated a go-around maneuver, the accident likely would not have occurred.
- The first officer's failure to maintain airspeed while acting as the pilot flying likely resulted from being distracted by the flap anomaly, the captain's actions in response to it, and the control force inputs needed to maintain aircraft control.
- The captain's failure to call out the first officer's airspeed deviations resulted directly from his preoccupation with performing an inappropriate, nonstandard procedure in response to the flap anomaly.
- Although some of the airspeed bugs (including the internal bug) were not set to the appropriate approach airspeeds and were not reset following recognition of the flap anomaly, the flight crew had a sufficient reference to maintain the minimum safe airspeed because the airspeed for a no flap approach in icing conditions was correctly briefed as 143 knots, and the red airspeed bugs were set near that value.
- Reliance upon flight crew vigilance and stall warning systems may be inadequate to prevent hazardous low airspeed situations, and, had a low airspeed alerting system been installed on the airplane, it may have directed the flight crew's attention to the decaying airspeed earlier and provided an opportunity to take corrective action before the stall protection system activated.
- The first officer's failure to assert herself to the captain and initiate a go around maneuver when she recognized the unstabilized approach likely resulted from the steep authority gradient in the cockpit and the first officer's minimal training on assertiveness; further, the captain's quick dismissal of the first officer's go around inquiry likely discouraged the first officer from voicing her continued concerns and challenging the captain's decision to continue the unstabilized approach.
- Role playing exercises are essential for effective assertiveness training because such exercises provide flight crews with opportunities for targeted practice of specific behaviors and feedback that a lecture based presentation format lacks.
- The establishment of best practices for conducting both single and multiple emergency and abnormal situations training needs to include training for the occurrence of these situations at low altitudes because low-altitude scenarios require rapid, accurate assessment of abnormal situations and appropriate prioritization of tasks.
- Although the risk for fatigue existed at the time of the accident due to the window of circadian low, the first officer took steps to mitigate the effects of fatigue, and her errors during the flight can be explained by her lack of experience in both the airplane and in icing conditions along with the distraction caused by the captain's non-standard response to the flap anomaly.
- Due to the early morning hour of the accident flight and cumulative sleep debt, it is likely that fatigue degraded the captain's performance.
- Dispatching and operating an airplane in known icing conditions for which the airplane is not certificated and has not demonstrated the ability to operate safely has the potential to reduce or eliminate safety margins.
- To most effectively ensure the safety of flight operations in icing conditions, pilots and dispatch personnel must understand how the dangers of freezing drizzle and freezing rain can affect their airplanes and must understand the differences between ground deicing considerations and in flight icing operations.
- The presence of ice on the taxiways between the aircraft rescue and firefighting station and the accident site minimally increased the response time; however, the emergency response was timely and effective in suppressing the fire.
- Timely information from the flight crew about the safety of the airplane occupants and the presence of on board hazardous materials cargo would improve the safety and efficiency of the emergency response.
- Because flight crews cannot always immediately communicate with air traffic control after an accident, it is important that another method be developed to communicate information, such as the number of occupants on board and the presence of hazardous material, to aircraft rescue and fire fighting personnel upon initial notification of an accident.
- An iced and inoperable mutual aid gate could extend the response time of mutual aid, which could delay the delivery of medical attention to accident survivors and result in further fire damage to property.
- The aircraft performance monitoring system is a valuable low airspeed alerting tool that can enhance safety in all icing conditions.
- If the accident aircraft had been equipped with a flap asymmetry light, as many other ATR 42 and all ATR 72 aircraft are equipped, the illumination of that light would likely have made the nature of the malfunction more salient to the flight crew, and may have triggered a more appropriate crew response.
- The absence of an ice evidence probe, which was an optional installation, did not hinder the flight crew's ability to detect airframe ice accretion.
- Simulator based training scenarios that realistically reflect aircraft performance degradations that result from airframe ice accretion can better prepare flight crews to effectively respond to decaying airspeed situations and other situations that can occur during in flight icing encounters.
As a result of this investigation, the National Transportation Safety Board makes the following recommendations to the Federal Aviation Administration:
- Require that role playing or simulator based exercises that teach first officers to assertively voice their concerns and that teach captains to develop a leadership style that supports first officer assertiveness be included as part of the already required crew resource management training for 14 Code of Federal Regulations Part 121, 135, and 91 subpart K pilots.
- Prohibit all 14 Code of Federal Regulations Part 121, 135, and 91 subpart K operators of pneumatic deice boot equipped airplanes from dispatching or deliberately operating these airplanes in known freezing rain or freezing drizzle of any intensity, unless the airplane manufacturer has demonstrated that the airplane model can safely operate in those conditions.
- Review the approved pilot, dispatcher, and flight follower training programs and procedures for all 14 Code of Federal Regulations Part 121, 135, and 91 subpart K operators and require revisions to the programs and procedures, as necessary, to include standardized training and aircraft specific information to educate pilots, dispatch, and flight follower personnel of the dangers of flight operations in freezing precipitation and of the differences between ground deicing considerations and in flight icing operations.
- Develop a method to quickly communicate information regarding the number of persons aboard and the presence of hazardous materials to emergency responders when airport emergency response or search and rescue is activated.
- Amend Advisory Circular 150/5200 30C to include guidance on monitoring and ensuring the operability of emergency response and mutual aid gates during winter operations.
- Require all operators of Avions de Transport Régional Aerospatiale Alenia ATR 42 and ATR 72 series airplanes to retrofit the airplanes with an aircraft performance monitoring system if they are not already so equipped.
- Define and codify minimum simulator model fidelity requirements for aerodynamic degradations resulting from airframe ice accumulation. These requirements should be consistent with performance degradations that the National Transportation Safety Board and other agencies have extracted during the investigations of icing accidents and incidents.
- Once the simulator model fidelity requirements requested in Safety Recommendation 7 are implemented, require that flight crews of all aircraft certificated for flight in icing conditions be trained in flight training simulators that meet these fidelity requirements. Such simulation training should emphasize the following: (1) cues for recognizing changes in the aircraft's flight characteristics as airframe icing develops; (2) procedures for monitoring and maintaining appropriate airspeeds in icing conditions, including the use of icing airspeed reference indices; and (3) procedures for responding to decaying airspeed situations, stall protection system activation, and early stalls that can occur without stall protection system activation.
- Require all ATR 42 aircraft not already equipped with a flap asymmetry annunciator light to be so equipped.