WASHINGTON – Two inertial reference units (IRUs) failed on the United Airlines (UA) Boeing 787-8 on January 24, 2025, just before the aircraft experienced a rapid altitude shift in Africa, causing 16 people to be injured. On March 18, the National Transportation Safety Board (NTSB) revealed the actual findings in a preliminary accident report.
According to the report, the jet's left IRU failed about an hour and five minutes before the altitude was agitated. This was followed by a proper IRU failure after about 55 minutes. The incident occurred on January 24th at 01:31 Lagos time on the United 613 flight 613 from Lagos (LOS) to Washington Dulles International Airport (IAD) while flying through Ivory Coast (CI).
United Airlines 787 IRUS Disability
United Airlines Flight 613 took off from Murtala Muhammed International Airport in Lagos (LOS) just before midnight on January 23, 2025.
Approximately 93 minutes after the flight, the aircraft suddenly descended. This caused luggage, personal belongings, food trays and other objects tossed violently throughout the cabin, as documented in videos shared on social media platforms.
The Federal Airports Authority of Nigeria (FAAN) reported that the flight carried 243 passengers and 11 crew members. The aircraft safely returned to Lagos (LOS) and landed around 3:22am on January 24, 2025.
Four passengers and two crew members needed hospitalization due to serious injuries, but were later discharged. A further 27 passengers and five crew members reported minor injuries.
United Airlines said the aircraft returned to Lagos due to “technical issues.” The airlines made it clear that the turbulence is not responsible for the sudden descent, indicating that they are working with aviation authorities in both the US and Nigeria to determine the actual cause of the incident.
Only in the NTSB's recent report release revealed that inertial reference unit (IRU) failures are behind what United Airlines previously described as “technical issues.”
United Airlines Flight #UA613 Makes Emergency Landing in Lagos: Six Seriously Injured Amid Mid-Air Incident
A United Airlines Boeing 787-8(N27903) Dreamliner, operating as flight UA613 from Lagos to Washington Dulles, was forced to return to Lagos after a mid-air technical issue… pic.twitter.com/FrHCjOpbN9
— Turbine Traveller (@Turbinetraveler) January 24, 2025
NTSB Report
Operated by the Boeing 787-8 registered as N27903, the United Flight UA613 departed Lagos at about 00:20am and climbed 36,000 feet. Following an IRU failure, seconds before the altitude becomes unsettled, the autopilot will automatically disconnect with the cockpit master warning and master warning alert active. The pilot quickly controlled the aircraft manually.
The sudden altitude change lasted for about 12 minutes. During this period, the 787-8 deviated from a cruising altitude of 36,000 feet. It reached a maximum height of 36,203 feet and fell to a minimum of 35,577 feet.
The NTSB report points out that the aircraft's stick shaker has been activated. That autothrottle was disconnected and re-involved before being cut for the second time.
Injuries and response
The advanced field trip occurred during meal service in the cabin, contributing to injuries. Of the 254 people on the jet, including 11 crew members and 243 passengers, 15 passengers were minor injuries and one passenger was seriously injured.
At 00:40, the flight crew decided to return to Lagos, where they safely landed.
Survey status
The location of the incident places the main investigative responsibility for the Cote de Boire authorities. Although they granted a request from the NTSB to assist with the investigation.
The 787-8 flight data recorder, inertial reference unit, and attitude heading reference unit were removed from the Lagos aircraft and shipped to Washington, DC for inspection.
NTSB noted that cockpit audio recordings were not accessible during the event as Jet's cockpit voice recorder only captured two hours of audio and was overwritten to an investigator's access time.
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