Delta Air Lines launched scheduled flights from Atlanta to Havana on Thursday morning, marking its long-awaited return 55 years to the day from its withdrawal from Cuba.

"It's a very historic milestone day for us, as we return to Cuba," said Delta's president of international Steve Sear at Hartsfield-Jackson International Airport before the flight took off.

Flight 639 from Atlanta to Havana took off at about 11:20 a.m. as one of three routes to Havana that Delta launched Thursday for the restart of scheduled flights to Cuba. A Delta flight from Miami landed in Havana earlier in the day, followed by a Delta flight from New York's John F. Kennedy International Airport to Havana.

"Hundreds of folks are involved in making these flights successful," said Delta's president of international Steve Sear. "There's so much enthusiasm."

The inaugural Atlanta-Havana flight was only about half-full, however, with a number of passengers pulling out of the trip in the wake of the death of Fidel Castro and the declaration of a nine-day period of mourning in Cuba. A delegation that was to be led by Atlanta Mayor Kasim Reed also withdrew from the trip.

The travelers on Delta's inaugural flight received a commemorative luggage tag, cigar, postcard and inaugural flight certificate. In-flight cocktails included mojitos.

Delta in recent years has operated limited charter flights to Cuba, but the launch of scheduled airline flights on multiple airlines this year will make it easier for many travelers to make the trip.

There are still restrictions for travel to Cuba, including a requirement that travel fall under one of 12 permitted categories such as people-to-people visits, family visits and professional meetings.

Delta is the only U.S. carrier in operation that previously flew to Cuba up until 1961, when the airline suspended its service from New Orleans to Havana due to "an unstable political climate and profitability challenges."