Casualties unknown

Instructor and passengers injured after warning buzzer sounded post-takeoff (N6AL)

Boulder, CO, US

On May 18, 1991, a Beech C23 (registration N6AL) operated by Dakota Ridge Aviation, Inc. was involved in an aviation accident near Boulder, CO. Investigators recorded the probable cause as: INADVERTENT STALL/MUSH DUE TO THE PASSENGERS'S DELAY IN RELINQUISHING AIRCRAFT CONTROL, AND INADEQUATE SUPERVISION OF THE FLIGHT BY THE PILOT IN COMMAND. FACTORS WERE: MIXTURE NOT LEANED, AND A HIGH DENSITY ALTITUDE TAKEOFF WITH A SLIGHT QUARTERING TAILWIND. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 2 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

A flight instructor allowed a passenger to perform takeoff while another passenger heard a continuous warning buzzer until impact. The instructor sustained serious injuries.

What happened

The rear seat passenger reported that the flight instructor permitted the front seat passenger to execute the takeoff procedure while providing verbal guidance through the steps. Shortly after the aircraft lifted off the runway, both passengers in the rear seat heard a warning buzzer sound. This audible alert continued without interruption until the moment of ground impact.

The investigation

Following the accident, investigators examined the condition and statements of the occupants to determine the sequence of events. The flight instructor sustained serious injuries during the incident. Due to the severity of these injuries, the instructor was unable to recall any specific details regarding the accident or the events leading up to it.

Findings

The primary finding relates to the operational control and communication within the cockpit during the critical phase of flight. The instructor delegated the physical control of the takeoff to a passenger while attempting to manage the procedure verbally. The presence of a warning buzzer that persisted until impact suggests a systemic or configuration issue that was not addressed or acknowledged by the crew before the accident occurred.

Safety message

This incident highlights the risks associated with allowing passengers to manipulate flight controls during critical phases such as takeoff, especially when auditory warnings are active. Clear communication and immediate response to cockpit alerts are essential for maintaining safety.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X16977. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.