On August 27, 2004, at approximately 1130 Pacific daylight time, a Boeing 757-200, N526UA, received minor damage when the number six leading edge slat wedge was struck by birds during the initial takeoff, and the composite wedge subsequently delaminated over or near Richmond, British Columbia, Canada. The Airline Transport rated pilot and Airline Transport first officer, and an unknown number of additional crew members and passengers were not injured. United Airlines was operating the airplane as flight 426 under Title 14 CFR Part 121. Visual meteorological conditions prevailed for the cross-country passenger flight that originated from Richmond, British Columbia, shortly before the incident and was destined to Chicago, Illinois. An IFR flight plan had been filed. The flight crew reported hearing a "grinding noise" during initial flap retraction after takeoff. A flight attendant subsequently notified the flight crew that there was a loud "hum and vibration" coming from the right wing. The captain instructed the flight attendant to scan the wing for any anomalies. The flight attendant notified the crew of damage to the wing's leading edge. The flight crew immediately diverted to Seattle, Washington, and performed a normal landing. A post event assessment of the slat by United Airline's engineering staff said "while there is no evidence of bird remains, it is our opinion that the damage was due to impact following takeoff, most likely bird, with subsequent damage caused by flight loads. The crew did not observe birds in the area. The characteristic of the damage does not lend itself to fatigue/delamination of the slat as cause." This incident was delegated to the NTSB by the Canadian TSB.