A malfunction in the air traffic control system at Haneda Airport (Tokyo's primary domestic and international hub) caused widespread flight delays beginning at 7:15 a.m. on the 21st, according to the Tokyo Airport Office of Japan's Ministry of Land, Infrastructure, Transport and Tourism. Both arriving and departing flights were significantly affected by the technical failure. The disruption highlights the vulnerability of one of Asia's busiest airports to system outages, with knock-on effects expected across Japan's aviation network.