The manager of the world's busiest airport has a clever way of describing the symbiotic relationship with dominant hub carrier Delta Air Lines.

"We see them [Delta] as very, very close partners," said Hartsfield-Jackson International Airport general manager Roosevelt Council. "There are times that we can get pretty pugilistic with each other. But you know, that's the nature of a relationship."

"Everybody knows that nobody makes you madder than the ones that you care about the most. We have those episodes," Council said during a speech at a DeKalb Chamber of Commerce luncheon Thursday, which was broadcast on the chamber's Facebook page.

Atlanta-based Delta makes up about 80 percent of the passenger traffic at the Atlanta airport, and with its partners operates about 1,000 daily departures from Hartsfield-Jackson.

The city of Atlanta last year struck a new 20-year lease with Delta for its hub at Hartsfield-Jackson.

"Airline negotiation is sort of an animal unto itself," Council said. "They want everything cheap and we want everything paid for."

In the end, Delta agreed to pay for about 60 percent of Hartsfield-Jackson's $6 billion expansion and modernization plan, Council said.

Part of the airport's plan is to expand parking as passenger traffic grows.

"If I don't have enough capacity, then these people will actually go to the airport parking that's off the airport," Council said. "I'm not trying to drive those people out of business, but I need the money that they would actually be getting paid. Parking revenue for us is our No. 1 revenue source.... We're not greedy, but it takes a lot to run this place."

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Cost soars for Hartsfield-Jackson curbside canopies project Hartsfield-Jackson's manager says about Delta: "There are times that we can get pretty pugilistic with each other. But you know, that's the nature of a relationship."