Accident Overview
Around 1100 LT, a maintenance team of four people in two Kia minivans was cleared to enter runway 08R for lighting maintenance. Two workers were positioned about 600 meters from the threshold, and two about 1500 meters from the threshold. Visibility was poor due to thick fog. At 11:04, the runway was vacated for landing traffic, and at 11:06, the vans were recleared to enter.
At 11:25:13, flight ROT3107, a Boeing 737-300, was cleared to enter runway 08R for takeoff, and cleared for takeoff at 11:26:07. Between 11:26:40 and 11:26:50, the control tower asked the maintenance workers if the runway was clear but received no reply. During the takeoff roll at 90 knots, the aircraft collided with one van parked about 600 meters from the threshold with its left engine and left main gear. The van was totally destroyed. The aircraft veered left off the runway and came to rest 137 meters left of the centerline and 950 meters from the threshold. All 123 occupants evacuated safely, and ground maintenance personnel were not injured.
Probable Cause
The official investigation determined the probable cause as: "The accident occurred due to incorrect authorization of the turnover and aircraft takeoff RO3107, without runway clearance." Contributing factors included: disruption in the activity of CTA EXE TWR, misperceptions regarding the clearance status of the runway, and cumulative lack of coordination between CTA EXE TWR and CTA GND/TAXI to release the track; incomplete application of RCAST and LVO provisions by traffic controllers, with the team supervisor failing to notice and correct; inconsistent use of progressive evidence bands; focus on calling the beaconing team instead of initiating immediate cancellation of the takeoff by transmitting "stop the takeoff" and stopping/starting runway lights; gaps in training and knowledge of procedures; mismanagement of human resources at TWR OTP leading to insufficient CTA personnel and absence of supervisor; and non-strict application of movement rules, radio communication rules, and LVO procedures, some of which contained unclear provisions.