The U.S. aircraft register, updated daily · Carbon Free Flight by 2050
Accidents · NTSB DCA23LA421 · Final report

Boeing 777-222 accident near Over The, AO, August 18, 2023

On August 18, 2023 at about 2:11 pm local time, a 1999 Boeing 777-222, registered N209UA, was involved in an accident near Over The, AO. It was flown under scheduled airline rules (Part 121). 1 person was seriously injured and 8 people had minor injuries; 247 others were unhurt. The weather was visual conditions (good weather).

Preview. This page is not yet listed for search engines.

The NTSB's probable cause their words, unchanged

An inadvertent encounter with clear air turbulence during cruise flight.

Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.

What the record shows

Date
August 18, 2023 · about 2:11 pm local time
Place
Over The, AO · map
Type
Accident
Injuries
1 person was seriously injured and 8 people had minor injuries; 247 others were unhurt.
Weather
visual conditions (good weather)
Aircraft
Boeing 777-222, built 1999 · all 777-222s on the register
Registration
N209UA · registry record · serial 30215
Damage
Not recorded
Flight
Flight · scheduled airline rules (Part 121)

The NTSB's narrative final · quoted from the NTSB record

United Airlines flight 918 encountered clear air turbulence during cruise flight, while en route to the London Heathrow International Airport (LHR), London, United Kingdom resulting in one flight attendant (FA) sustaining a serious injury. The flight originated at Dulles International Airport (IAD), Dulles, Virginia. The flight crew reported that their preflight weather briefing revealed no significant areas of weather or turbulence over their planned route to LHR. During their preflight checks an open status message “PASS ADDRESS SYSTEM” displayed on their engine indication and crew alerting system (EICAS) display and maintenance was called. A technician responded who reinitialized the entire passenger address (PA) system and cleared the status message. The flight crew reported that prior to the JOBOC intersection, there was minimal light turbulence, and the seatbelt sign had been on and off sporadically as required. They also indicated that no turbulence was identified in their immediate vicinity from their inflight weather resources. About 80 nm east of JOBOC, the flight encountered very light turbulence and the first officer (FO), who was the pilot flying, made the PA announcement: “Flight Attendants take your seats.” In a postaccident statement, the captain reported that while in the forward lavatory, the flight encountered very light turbulence and he heard through the lavatory wall, the FO make the PA announcement: “Flight Attendants take your seats.” However, because he did not hear the PA announcement over the lavatory speaker he didn’t know if the rest of the crew or passengers heard this announcement.  The in-flight service manager (ISM), who was in the cockpit at the time also heard the FO make the announcement “Flight Attendants take your jumpseats.” As the captain attempted to take his seat (left seat) the flight encountered a moderate turbulence spike that made his knees buckle and threw him back down into the 1st observer’s seat. He indicated that he was able to flash the seatbelt sign on and off three times rapidly. The flight crew then executed all the steps of the TURBULENCE IMMEDIATE ACTION GUIDE. The turbulence ended as abruptly as it had begun. The captain then made a PA announcement “Flight attendants check in.” The ISM advised the captain that all the flight attendants had been knocked to the floor and one was seriously injured. The flight crew contacted dispatch and advised of the clear air turbulence encounter. The dispatcher had no reports of turbulence from any other United flights in the area. According to the cabin crew, they did not hear the PA announcement “Flight Attendants take your seats” and therefore they were completing their normal duties when, without warning, the airplane encountered turbulence. One FA, who was delivering meals at the time of the turbulence encounter, was thrown down, impacted the floor, and was injured. According to the ISM, shortly after the encounter, the captain came on the PA and said “Flight Attendants, Check In.” The cabin crew heard that announcement and the ISM reported to the flight crew that one FA was on the floor and was unable to get up. Upon being notified of the injured FA, the flight crew declared a medical emergency and requested paramedics meet the aircraft at the gate in LHR. The injured FA was moved to an unoccupied passenger seat, given ice, and was assisted by an onboard medical doctor for the rest of the flight. After landing the FA was transported to a local hospital where she was diagnosed with a fractured left fibula. A postaccident functional check of the passenger address system revealed no malfunctions or anomalies with the system.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.

The factual record from the NTSB's investigation tables, in plain English

What happened, in order

  1. 402360 during 402

The NTSB's findings

  • Environmental issues › Conditions/weather/phenomena › Turbulence › Clear air turbulence › Effect on personnel
  • Environmental issues › Conditions/weather/phenomena › Turbulence › Clear air turbulence › Awareness of condition
  • Personnel issues › Experience/knowledge › Knowledge › Knowledge of meteorologic cond › Cabin crew
  • Personnel issues › Experience/knowledge › Knowledge › Knowledge of meteorologic cond › Flight crew
  • Personnel issues › Physical › Impairment/incapacitation › Illness/injury › Cabin crew

Pilot

  • Ratings: multi-engine land, single-engine land, none, none, none
  • Flight time: 21,000 hours in all; 3,441 in this make and model; 214 in the last 90 days; 73 in the last 30 days; 18,307 as pilot in command
  • Medical certificate: class 1
  • Injury: no injuries

Co-pilot

  • Ratings: multi-engine land, none, APLN, none
  • Flight time: 15,000 hours in all; 1,575 in this make and model; 245 in the last 90 days; 88 in the last 30 days; 10,000 as pilot in command
  • Medical certificate: class 1
  • Injury: no injuries

Flight instructor

  • Flight time: 0 hours in all; 0 in this make and model
  • Injury: no injuries

Cabin Crew

  • Injury: no injuries

Cabin Crew

  • Injury: serious injuries

Cabin Crew

  • Injury: no injuries

Cabin Crew

  • Injury: no injuries

The aircraft

  • Airframe total time: 92,517 hours
  • Last inspection: continuous airworthiness programme, September 22, 2023
  • Maximum gross weight: 568,669 lb
  • Seats: 380
  • Landing gear: fixed
  • Engine 1: P&W PW4000 SER (turbofan); 0 hours total
  • Engine 2: P&W PW4000 SER (turbofan); 0 hours total
  • Operator: United Airlines INC
  • Operating certificate: in the vicinity

The flight

  • Departed from: KIAD Dulles VA at 2:20 am
  • Destination: LHR London OF
  • Flight plan: IFR

Weather at the time

  • Light: night
  • Wind: at 65 knots
  • Visibility: 10 statute miles
  • Sky: clear
  • Temperature: 0°C, dew point 0°C
  • Observation at 6:40 pm from CYQX

Injuries

FatalSeriousMinorNone
Flig184
Passengers243

Other NTSB records under N209UA the same tail number, which may have belonged to a different aircraft at the time

2009-11-19DCA10FA012 · accident near New Market, VA · serious injuries

About this page

Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The docket at the NTSB holds the report as a PDF and the investigation's photographs and documents. This site never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number DCA23LA421.