2 Mar 2016: CURTISS WRIGHT TRAVEL AIR 4000 NO SERIES (N6464) — Palmer Lake, CO

2 fatalitiesPalmer Lake, CO, United States

A vintage biplane crashed near Palmer Lake, Colorado, resulting in the deaths of both occupants after the aircraft entered an aerodynamic stall/spin.

On March 2, 2016, a 1928 Curtis Wright Travel Air 4000, registration N6464, crashed near Palmer Lake, Colorado, during a flight from Longmont to Arizona. The accident resulted in 2 fatal injuries, claiming the lives of the pilot and a pilot-rated passenger.

What happened

At approximately 0715, the aircraft departed Vance Brand Airport, en route to a fly-in gathering in Casa Grande, Arizona. During the flight, witnesses observed the airplane flying at a low altitude and low airspeed over a frozen lake. One witness noted the aircraft appeared to be making a "low slow scenic pass" and was flying into a significant headwind.

Multiple witnesses reported seeing the aircraft struggle with stability, noting it was "listing" left and right. The aircraft was observed performing a left turn at an altitude of approximately 200 feet before entering a nose-dive into the ground. A post-impact fire consumed much of the aircraft's wooden and fabric structure.

The investigation

Investigators examined the wreckage and found the main components of the N6464 had impacted the ground in a nose-down attitude. While the rudder cables showed evidence of an overload break, the examination of the airframe, engine, and control systems revealed no evidence of pre-impact mechanical anomalies. The engine's oil screen contained soil and rocks consistent with the impact site, and the carburetor was fractured from the engine.

Meteorological data indicated that while some local reports suggested calm winds, other nearby stations and area forecasts indicated strong, gusty winds from the west, with gusts reaching up to 48 knots in the vicinity around the time of the accident.

Toxicology analysis of the pilot revealed the presence of chlorpheniramine, a sedating antihistamine. This substance is known to potentially impair psychomotor functions, such as visual-spatial cognition and motor coordination.

Findings

  • The pilot failed to maintain sufficient airspeed while maneuvering at a low altitude during periods of strong, gusty winds.
  • The aircraft exceeded its critical angle of attack, resulting in an aerodynamic stall/spin.
  • The pilot's ability to safely operate the aircraft was likely impaired by the effects of a sedating antihistamine.

Probable cause

The pilot's failure to maintain sufficient airspeed while maneuvering at low altitude in strong gusting winds, which resulted in exceedance of the airplane's critical angle of attack and an aerodynamic stall/spin. Contributing to the accident was the pilot's impairment due to the effects of a sedating antihistamine.

Contributing factors

Causes

Airspeed — Not attained/maintainedCapability exceededEffect on operation

Other contributing factors

Pilot