MENDOTA HEIGHTS, Minn. (AP) - The chairman of Sun Country Airlines is threatening to ground its planes during a pay dispute with the pilots union.

A letter from Marty Davis to the union said the company's management has "begun the process of downsizing the airline, for what will need to be its ultimate shut-down."

Reports say the company declined to comment. The pilots union dismissed the letter as a bargaining tactic.

Federal records indicate the carrier has been consistently profitable since 2009. The pilots union argues that no other sizable airline pays pilots less for flying Boeing 737s.

The pilots have voted to authorize a strike, but a walkout does not appear imminent.

A spokesman for Minneapolis-St. Paul International Airport says Sun Country has not expressed interest in ending its airport leases.