On the 18th of April, 2017 at 17:00 h, a Bombardier DHC-8-Q400 aircraft with nationality and registration marks 5N-BPU, operated by Aero Contractors Company of Nigeria Limited as a scheduled flight NIG316, on an Instrument Flight Rule (IFR) Flight Plan, departed Port Harcourt International Airport for Murtala Muhammed International Airport Lagos with 4 crew and 53 passengers on board. The captain was the pilot flying (PF) while the co-pilot was the pilot monitoring (PM). The incident flight was the sixth sector and the last flight scheduled for the day as the aircraft had operated five previous sectors.
At about 17:50 h while the aircraft was cruising at FL240, 80 NM to Lagos, the Lead crew informed the cockpit crew about the appearance of an odourless and non-irritant smoke in the cabin. The forward lavatory smoke detector activated.