Skymark Airlines Inc said on Jun. 9 that it will cancel 633 flights in the three months to August due to its pilot shortage.

Skymark earlier said it would cancel 168 flights this month after two of its pilots retired due to health reasons.

The manpower shortage will continue to disrupt operations until the end of August, the airline said.

Skymark Airlines has operated an average of 1,700 monthly flights on five routes, including those linking Tokyo's Haneda airport with Asahikawa and Sapporo, both in Hokkaido, and Fukuoka, on the basis of about 40 pilots.

The airline also revised downward operating revenue and profit estimates for the current business year to next Mar. 31, citing the impact of the large-scale flight cancellations as well as an upsurge in the costs of jet fuel.