Awwal 08, 1432, Feb 11, 2011, SPA -- A spokesman for Pakistan's state-owned airline says a growing strike by employees has grounded all of its flights, leaving thousands of passengers stranded, according to AP. The strike entered its fourth day on Friday. The pilots and support staff of Pakistani International Airlines are unhappy with a proposal to share routes with Turkish Airlines. PIA spokesman Mashhood Tajwar says at least 250 flights have been canceled since the strike began. He says no domestic or international PIA flights were in the air on Friday in any city. The carrier has also closed its main booking office in the southern city of Karachi. PIA managers say the route-sharing idea will save the financially struggling airline money, but strikers fear it will lead to job and pay cuts.