Despite the headwinds of high jet fuel prices creating havoc in the aviation industry, Las Vegas-based Allegiant Air remains on track to complete its planned merger with Minnesota-based Sun Country Airlines later this month. In a conference call with investors Thursday, Allegiant executives said they expect shareholders from both companies to consider the $1.5 billion deal on May 8 with the anticipated close of the transaction on May 13. Regulators already have signed off on the transaction that would blend two of the nation’s largest and most successful leisure air carriers. The airline initially expected the merger’s completion in the second half of this year. The combination brings together complementary route networks across Allegiant’s small and mid-sized localities and Sun Country’s larger cities and will provide more than 650 routes, including 551 Allegiant routes and 105 Sun Country routes. Between them, the two airlines have about 22 million passengers annually.…