A United Boeing 787-9, registration N26952 performing flight UA-2862 (scheduled dep May 13th, actual dep May 14th) from Hong Kong (China) to San Francisco,CA (USA) with 4 crew, was enroute at FL400 over the Pacific Ocean about 470nm east of Tokyo Narita Airport (Japan) when the crew decided to declare PAN PAN reporting the captain's winsdshield had cracked, to turn around maintaining FL400 and divert to Tokyo Narita for a safe landing on runway 16R about 90 minutes later on May 15th just past midnight.
The flight had departed Hong Kong with a delay of almost 21 hours on May 14th. The aircraft had arrived in Hong Kong on May 13th on schedule, but remained on the ground for 24 hours before continuing onto the next leg to SFO.