The Air Force says a series of system malfunctions led to the crash of a drone which crashed into Lake Ontario late last year.

The MQ-9 Reaper crashed November 12, 2013 after taking off from Fort Drum.

According to an Air Combat Command Accident Investigation Board report released Tuesday, the drone departed Wheeler-Sack Army Airfield for the Oswego Military Operating area to conduct a routine training mission.

Control of the MQ-9 was turned over from the launch recovery element (LRE) aircrew to the mission control element aircrew (MCE) at Hancock Field.

During the training mission, the MCE aircrew noticed a series of warnings indicating a partial failure in the MQ-9's onboard GPS and inertial navigation system.

In response, the report said the MCE aircrew at Hancock Field initiated the appropriate emergency checklist and informed the LRE aircrew of the situation. 

While the MCE aircrew was in the process of returning the MQ-9 to Wheeler-Sack Army Airfield, the aircraft lost link with the MCE aircrew and began to fly its pre-programmed contingency return-to-base flightpath on its own.

This pre-programmed flightpath allows the aircraft to return to base via a series of waypoints designed to safely avoid populated areas and potential obstructions.

The MCE aircrew followed the checklist instructions and disabled their command link to the aircraft to enable the LRE aircrew to attempt to gain control.

While the LRE aircrew was initiating the link through their ground data terminal transmitter, the MQ-9 suffered an additional failure in its GPS and inertial navigation system.

A few seconds later, the aircraft began an autopilot turn to the right that inverted the aircraft and eventually led to an unrecoverable flat spin.

Shortly thereafter, the MQ-9 impacted Lake Ontario and was destroyed.

The accident investigation board president found evidence that the cause of the aircraft crash was multiple failures within the MQ-9's GPS and inertial guidance system, in conjunction with that system passing invalid flight control data to the aircraft's autopilot system.

The aircraft was was assigned to the 174th Attack Wing.

The drone, valued at $10.6 million, was destroyed on impact.

There was no damage to private property.