More than 2,300 aviation workers took part in the strike, including 1,200 Cathay cabin crew and pilots, according to the Hong Kong Confederation of Trade Unions.
Service was suspended for more than an hour Monday morning on the Airport Express, which is a line that zips people between the airport and the city center in under 25 minutes.
Hong Kong air space and runway capacity at the airport has been effectively reduced by 50% for all airlines, according to an internal Cathay Pacific memo seen by CNN that was sent to staff that supports pilots and ensures planes operate efficiently and on time.