Accident at Lubbock, Texas, 27 Jan 2009

Accident narrative

On January 27, 2009, about 0437 central standard time, an Aerospatiale Alenia ATR 42-320 operating as Empire Airlines Flight 8284 crashed short of the runway during an instrument approach to Lubbock Preston Smith International Airport in Lubbock, Texas. The captain sustained serious injuries, and the first officer sustained minor injuries. The airplane, which was operating as a Part 121 supplemental cargo flight for FedEx Corporation, was substantially damaged by impact forces and a post-crash fire.

**The flight** Flight 8284 departed from Fort Worth Alliance Airport about 0313 on an instrument flight rules flight plan to Lubbock. The flight crew consisted of a 52-year-old captain and a 26-year-old first officer. The captain had accumulated 13,935 total flight hours, including 2,052 hours in the ATR 42, and had extensive experience flying in icing conditions. The first officer had 2,109 total flight hours, with 130 hours in the ATR 42, and had limited experience in icing conditions.

Instrument meteorological conditions prevailed in the Lubbock area. The National Weather Service had issued an airmen’s meteorological information (AIRMET) advisory for moderate icing conditions, and weather observations at Lubbock reported light freezing drizzle and mist, an overcast ceiling at 500 feet above ground level, and a temperature of -8° C.

During the initial descent, the first officer was the pilot flying with the autopilot engaged. The captain performed the descent and approach checklists and confirmed that the airplane’s anti-icing and deicing protection was set to level 3. During the approach briefing, the captain erroneously briefed the airspeed bugs for a takeoff in icing conditions rather than the airspeeds for an approach in icing conditions. However, he correctly stated that the minimum airspeed for a zero-flap approach in icing conditions was 143 knots, and both pilots set their red airspeed bugs near that value.

At 0422:32, the approach controller cleared the flight to 6,000 feet and advised the crew of the light freezing drizzle. At 0433:13, the flight was cleared for the instrument landing system (ILS) approach to runway 17R.

**The approach** Both pilots later stated that the airplane accumulated ice during the descent. At 0434:24, the first officer called for a flap setting of 15 degrees, the deployment of the landing gear, and the landing check. Flight data recorder (FDR) information showed that a flap asymmetry occurred: the left flaps extended partially (8 to 10 degrees) while the right flaps did not extend. The autopilot countered the resulting right-rolling tendency by applying aileron deflection that resulted in a 20-degree left control-wheel movement.

The first officer later recalled that the airplane accelerated in the descent, which she noted was unusual for the airplane in a flaps- and gear-down configuration. She decreased engine power to about 3 percent torque. At 0435:03, she asked, "what the heck is going on?" One second later, the captain replied, "you know what? we have no flaps." At this time, the airplane was at an altitude of about 1,400 feet just outside the final approach fix.

Neither crewmember discussed a procedure or checklist to address the flap problem. The first officer continued to fly the approach with the autopilot engaged while the captain got out a flashlight and turned around to check the circuit breakers behind the first officer’s seat. The captain later stated he moved the flap handle back to the 0-degree position because he did not want the flaps to travel inadvertently.

Between 0434:58 and 0435:25, the airplane's airspeed decreased from about 160 to 125 knots. At 0435:30, the aural stall warning and tactile stick shaker activated. The stick-shaker activation automatically disconnected the autopilot when the airplane was about 900 feet above ground level.

The first officer increased engine power to about 70 percent torque and began manually flying the approach. The airplane deviated high and to the right of the ILS glidepath. At 0435:40, the first officer asked, "should I go around," and the captain replied, "no," and then stated, "keep descending."

At 0435:44, the first officer stated, "we're getting close here," her voice sounding strained on the cockpit voice recorder. The captain asked if she wanted him to finish the approach, and she replied, "yes please."

The captain took control at 0435:50 when the airplane was about 700 feet above ground level at 143 knots. At 0435:56, he reduced the engine power to about 10 percent torque. At 0436:00, the aural stall warning and stick shaker activated again, concurrent with a terrain awareness and warning system (TAWS) warning of "pull up. pull up." The airplane was about 500 feet above ground level at 156 knots.

At 0436:02, FDR data indicated that the left and right flaps moved to a symmetric position of approximately 4.5 degrees, removing the need for control inputs to counteract the asymmetry. However, as the airplane continued to descend, its airspeed decreased. At 0436:17, the captain called for maximum propeller speed. At 0436:19, when the airplane was about 200 feet above ground level at 124 knots, the stall warning and stick shaker activated a third time. The airplane began to roll right, reaching a 35-degree bank, then rolled left to a 50-degree bank, and then right again before impacting the ground at 0436:27.

The airplane slid about 2,500 feet. A fuel-fed fire erupted on the right wing. The captain and first officer opened the forward cargo door, exited the airplane, and ran to a nearby company hangar.

**What the investigation found** The Board's investigation evaluated the airplane's systems, the weather, and the crew's performance.

**The flap asymmetry and aircraft performance** Impact and fire damage to the right flaps limited the extent to which pre-impact system integrity could be determined. X-ray examinations and disassembly of all four flap actuators revealed no evidence of mechanical restriction or jamming. Because of the extent of the damage, the Board concluded that the reason for the airplane's flap asymmetry could not be determined.

Aerodynamic coefficient extraction and calculations indicated that airframe ice accretion degraded the airplane's performance during the flight. However, the Board's performance study and simulator evaluations determined that the performance degradation due to ice accretion never exceeded the airplane's thrust performance or flight control capabilities. The Board concluded that the airplane was controllable with the flap asymmetry and airframe ice contamination and could have been maneuvered and landed safely if the minimum safe airspeed had been maintained.

**Crew performance and CRM** The Board found that the flight crew failed to follow standard operating procedures (SOPs) in response to the flap anomaly. Both pilots had been trained to perform a go-around maneuver and reference the quick reference handbook (QRH) if a flap problem occurred during an approach. Instead, the captain began a nonstandard troubleshooting procedure by checking circuit breakers, which distracted him from his duties as the pilot monitoring. The Board concluded that the captain's failure to call out the first officer's airspeed deviations resulted directly from his preoccupation with this inappropriate procedure.

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, and the control force inputs needed to maintain aircraft control. Furthermore, the Board found that the first officer's failure to assert herself and initiate a go-around maneuver when she recognized the unstabilized approach likely resulted from a steep authority gradient in the cockpit and her minimal training on assertiveness. The captain's quick dismissal of her go-around inquiry likely discouraged her from challenging his decision to continue.

The Board concluded that the captain's failure to immediately respond to the aural stall warning, the stick shaker, and the TAWS warning resulted in his inability to arrest the airplane's descent. Had the captain complied with SOPs and initiated a go-around, the accident likely would not have occurred.

**Fatigue** The accident occurred about 0437, during the window of circadian low. The first officer had taken steps to mitigate fatigue by maintaining a nighttime sleep schedule during her off-duty days. However, the captain stated he needed 6 to 8 hours of sleep per night to feel rested, and in the 72 hours before the accident, he had sleep opportunities of 10, 6, and 5.5 hours. The Board concluded that due to the early morning hour of the accident flight and a cumulative sleep debt, fatigue likely degraded the captain's performance.

**Dispatch and emergency response** The flight was dispatched into known light freezing drizzle. The Board noted that freezing drizzle is outside the icing envelope specified in 14 CFR Part 25, Appendix C, for which the airplane was certificated. The Board concluded that dispatching and operating an airplane in known icing conditions for which it is not certificated has the potential to reduce or eliminate safety margins.

Following the crash, aircraft rescue and firefighting (ARFF) units arrived on scene within 4 minutes and quickly suppressed the fire. However, because the flight crew left the scene without immediately notifying first responders of their safe evacuation or the presence of hazardous materials on board, ARFF personnel unnecessarily entered the burning wreckage to search for survivors. Additionally, one responding fire department unit was delayed because an automated airport access gate was frozen shut by ice.

**Probable cause** 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.