On 10th September 2020 at 15:02 h, a Bae125-800B aircraft with nationality and registration marks 5N-BOO, operated by Gyro Air Limited, arrived Osubi from Abuja for a drop-off and return flight to Abuja same day. The flight was scheduled to depart Osubi airstrip Warri, (DNSU) to Nnamdi Azikiwe International Airport, Abuja (DNAA) at 15:13 h on an Instrument Flight Rules (IFR) flight plan. There were 3 crew members on board and fuel endurance of 3hours 30 minutes. The Pilot was the Pilot Flying (PF) while the Co-pilot was the Pilot Monitoring (PM).
At 15:18:24 h, 5N-BOO requested engine start up and cruising at Flight Level (FL) 210 above mean sea level from Osubi Tower (TWR). TWR granted the start-up and instructed 5N-BOO to report when ready for taxi. At 15:19:31 h, the flight crew completed the BEFORE START Checks, started the engines and reported to the TWR, 5N-BOO ready for taxi. TWR granted 5N-BOO taxi clearance. 5N-BOO was further cleared to enter and back track for takeoff on Runway (RWY) 24.
At 15:22:32 h, the flight crew completed the BEFORE TAKEOFF Checks. At 15:23:18 h, the flight crew completed the LINE-UP Checks. While advancing the thrust levers for a short field takeoff roll, an AgustaWestland (AW) 139 helicopter with registration 5N-CHO operated by Caverton Helicopters called the TWR. TWR asked 5N-CHO to go ahead.
