Hong Kong, Oct. 6 -- Alaska Airlines has ended its codeshare agreement with Singapore Airlines (SIA). The airline said in a letter to the U.S. Department of Transportation (DOT) the codeshare agreement was "no longer effective" from October 1. Read More The termination of the agreement removes SIA's SQ airline code on Alaska Airlines-operated flights to select cities in the U.S. from Los Angeles, San Francisco and Seattle. While the codesharing ended on October 1, SIA said in notice on its website its KrisFlyer frequent flyer members could still earn miles on Alaska Airlines flights flown up to December 31 this year. Also, award tickets issued by SIA prior to September 30 for Alaska Airlines-operated flights with a travel date after Septemb...