On 10th September 2020 at 15:02 h, a BAe 125-800B aircraft with nationality and registration marks 5N-BOO, operated by Gyro Air Limited, arrived Osubi from Abuja for a drop-off and return to Abuja.
The flight was scheduled to depart Osubi Airport 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 3 h, 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 for engine start up and cruising altitude of 22,000 ft above mean sea level (FL220) from Osubi Tower (TWR). TWR granted the start-up and instructed 5N-BOO to report when ready for taxi.
At 15:19:13 h, the flight crew completed the before start up checks, started the engine 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 15:22:15 h, during taxi TWR issued departure clearance to 5N-BOO for initial climb to FL50 and to request level change en-route. TWR subsequently cleared 5N-BOO for takeoff RWY 24 with an instruction to turn right after take-off. 5N-BOO read back the clearance and TWR confirmed it is correct.
At 15:25:13 h, the flight crew completed the line-up and before takeoff checks. While advancing thrust for short field takeoff roll, an Augusta Westland (AW) 139 helicopter with registration 5N-CHO operated by Caverton Helicopter called TWR. TWR asked 5N-CHO to go ahead.