What happened
On the scheduled international cargo flight IR123, traveling from Kabul, Afghanistan, to Tehran, Iran, a significant mechanical issue occurred during the departure phase. While accelerating on runway 29, the crew observed that the number one engine propeller was experiencing an overspeed condition, with RPM levels surging as high as 3300.
As the aircraft reached approximately 80 knots, the captain assumed control of the flight. During this period, the aircraft began drifting leftward away from the runway centerline toward the edge of the concrete footing and runway lighting. In an attempt to prevent a collision with these lights, the pilot applied elevator input to lift the aircraft type off the ground.
Despite following established operational procedures to address the surging propeller, the malfunction persisted. The flight path deviated significantly from the runway, turning roughly 30 to 45 degrees to the left toward the Kabul Airport terminal area. In an effort to steer clear of the terminal building, the pilot continued a leftward turn. During this maneuver, the left wing struck the ground approximately 325 feet from the southern edge of the runway, resulting in the crash of the aircraft type. There were 0 fatalities and no specific injury counts were reported for the crew.
Findings
Investigations into the accident determined that the primary factor was the captain's decision to continue the takeoff roll despite the visible overspeeding of the number one propeller while the aircraft was still on the runway.