Bering Air 445: The Final Descent Into Severe Icing

A Cessna Caravan approaching Nome slowed to stall speed in severe icing after the aircraft was operated above maximum gross weight.

Accident Facts

A Routine Commuter Flight

The accident occurred during the third leg of the pilot's scheduled three-leg round trip. The final flight departed Nome for Unalakleet and then returned toward Nome. The pilot used the autopilot for most of the final flight. Before the day's flying began, the dispatcher reviewed the weather with the pilot, who reportedly had no concerns based on the information available at that time.

The Weather Became More Severe

About 38 minutes into the final leg, the airplane encountered severe icing, including supercooled large droplets. The TKS ice-protection system was functioning and investigators found that it prevented significant ice buildup on protected surfaces. However, the icing conditions were more severe than forecast and outside the certification envelope used for certain icing conditions.

The Runway Closure Changed the Workload

At about 15:12, Nome closed both runways for deicing. The controller told the pilot that the closure was expected to last 10 to 15 minutes and suggested slowing down. The pilot reduced engine power and the aircraft slowed from about 160 knots to about 110 knots, then increased power and speed to about 126 knots.

The Autopilot Disconnected

At about 15:19 the aircraft's airspeed again fell, reaching about 99 knots. That activated the low-airspeed awareness system, which was designed to disconnect the autopilot. Recorded data then showed the aircraft descending at about 2,000 ft/min and pitching up to roughly 10–12°. Over the next several seconds airspeed fell to about 70 knots at 3,100 ft.

The Weight Problem

The final report found that the aircraft was above maximum gross weight. The investigation also found a pattern of underreported weights on Bering Air manifests, with several flights operating above weight limits. The overweight condition reduced the aircraft's stall margin, meaning that the aircraft could reach the aerodynamic stall at a higher speed than it otherwise would.

What the Investigation Found

The NTSB concluded that workload and degraded situation awareness affected the pilot's airspeed management. The report found that improper control inputs increased angle of attack during the final sequence. The aircraft entered an aerodynamic stall and lost control. The NTSB also identified inadequate operator safety management and inadequate FAA oversight as contributing factors.

Sources & Reconstruction Note

• https://data.ntsb.gov/Docket?NTSBNumber=ANC25MA018
• https://data.ntsb.gov/Docket?NTSBNumber=ERA14CA088