Loss of Control During Night Instrument Approach

Casualties unknown • Swanzey, NH, US

A twin-engine aircraft experienced a loss of control during a night precision instrument approach due to an asymmetric power setting and low airspeed.

What happened

While en route to the company's home airport, the twin-engine airplane experienced either a loss of power to the right engine or the pilot elected to shut the engine down. Although the destination airport offered night visual meteorological conditions, the pilot chose to fly a night precision instrument approach to an airport located 45 nautical miles closer. This alternate airport reported a 1-mile visibility and a 100-foot ceiling, with fog also present at the site.

The pilot did not notify air traffic control or the company regarding this change in plan. As the aircraft emerged from the clouds, it was in an unstable condition. While approaching the runway with full flaps—exceeding the 25 percent maximum limit for a go-around—the pilot applied full power to the left engine. The combination of high power on one side, low airspeed, and full flap configuration resulted in a minimum control speed (Vmc) roll.

The investigation

Investigators were unable to determine why the right engine was inoperative. The examination found no mechanical or fuel-related anomalies that would have prevented normal operation of the engines.

Probable cause

The loss of control was caused by a minimum control speed roll resulting from the application of full power on the operating engine while flying at a low airspeed and with flaps extended beyond the recommended limit for a go-around.

Frequently asked questions

What happened in the 2005-01-14 Embraer EMB-110P1 accident near Swanzey, NH?

A twin-engine aircraft experienced a loss of control during a night precision instrument approach due to an asymmetric power setting and low airspeed.

What aircraft was involved and where did it happen?

The accident on 2005-01-14 involved a Embraer EMB-110P1, registration N49BA, at Swanzey, NH.

What was the probable cause of the accident?

The loss of control was caused by a minimum control speed roll resulting from the application of full power on the operating engine while flying at a low airspeed and with flaps extended beyond the recommended limit for a go-around.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20050124X00092. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.

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