26 Years ago today: On 7 November 1996 an ADC Boeing 727 lost control and crashed during an evasive manoeuvre to avoid collision while approaching Lagos, killing all 143 occupants.

Date:Thursday 7 November 1996
Type:Silhouette image of generic B722 model; specific model in this crash may look slightly different
Boeing 727-231
Operator:ADC Airlines
First flight:1969-04-29 (27 years 7 months)
Total airframe hrs:64956
Engines:Pratt & Whitney JT8D-9A
Crew:Fatalities: 10 / Occupants: 10
Passengers:Fatalities: 134 / Occupants: 134
Total:Fatalities: 144 / Occupants: 144
Aircraft damage:Destroyed
Aircraft fate:Written off (damaged beyond repair)
Location:7,5 km (4.7 mls) W of Ejirin (https://cdn.aviation-safety.net/database/country/flags_15/5N.gif   Nigeria)
Phase:Approach (APR)
Nature:Domestic Scheduled Passenger
Departure airport:Port Harcourt Airport (PHC/DNPO), Nigeria
Destination airport:Lagos-Murtala Muhammed International Airport (LOS/DNMM), Nigeria

ADC Airlines flight 086 was destroyed when it crashed into a lagoon near Ejirin, Nigeria. All 144 on board were killed.
The aircraft, a Boeing 727-231, departed Port Harcourt at 15:52. The trainee copilot was Pilot Flying, the captain was Pilot Monitoring on the flight to Lagos.
It was cleared by Port Harcourt ATC to the cruising altitude of FL240.
At 15:47 the flight established initial contact with Lagos Approach Control, and was assigned a transponder code. At 15:54 the flight reported crossing SEPER point. After this position report, the flight appeared not to be maintaining a listening watch, as it gave no reply to two consecutive calls from Approach Control, and then after some time replied to a transmission not meant for it
At the same time a Triax Airlines Boeing 727 (Flight 185) had departed Lagos and was flying at FL160 towards Enugu. The Lagos controller had terminated contact with the Triax aircraft when the ADC crew requested to descend. The permission to descend was delayed to allow a corporate jet (5N-APN) to pass beneath the 727 at FL210.
At 15:59 Lagos Approach Control then cleared the flight to FL160 and subsequently requested the flight to contact Lagos Radar.
The flight was identified by Lagos Radar 41 miles south-east of the airport, and instructed it to fly the heading of 320° to avoid Triax flight 185, and to descend to FL50.
At 16:02.50 Lagos Radar instructed the aircraft two times in succession to maintain heading 300. The captain then took over control from the copilot by stating: “I have it.”
At 16:03.08 the flight reported: “I have the traffic… and I continue my heading to 330 to avoid him”. This was the last transmission.
The records of the FDR show that flight 086 was maintaining a steady coordinated turn towards heading 330 for the first 10 seconds of the last 50 seconds of the flight. After 15 seconds, the airplane was put in bank angle of 43.2 degrees. It maintained this configuration for 10 seconds before the bank angle increased to 68.8 degrees. This attitude was observed for 5.5 seconds before it was further increased to 83 degrees. The airplane must have suffered from high speed stall and gone into a roll with a nose down attitude.
The aircraft appeared to be recovering just before it impacted the lagoon water because it succeeded in reducing the vertical acceleration from 8.44 to 2.1 G and the bank angle to 61.6 degrees. But it did not have sufficient height to make a full recovery.
The aircraft crashed and disintegrated on impact.
Probable Cause:

IMMEDIATE CAUSE: “The untidy traffic separation by the radar controller which resulted from the vectoring of ADK 086 towards the track of the opposite traffic TIX 185.”
REMOTE CAUSE: “The error of judgement by the pilot of ADK 096 to continue his turn to heading 330 M to avoid TIX 185 and his subsequent collision avoidance manoeuver constituted the remote causes of this accident.”