Announcing a blockbuster airline merger is the easy part. The hard part is pulling one off smoothly. Here are some of the issues that will keep Delta managers busy for months or even years to come:

EMPLOYEES:: Airline mergers are notorious for fostering ill will among workers who feel they got the short end of the stick on seniority, pay, job location or other matters. Delta got its own pilots on board with a new contract ahead of the deal but will still have to get an agreement with Northwest pilots, who already are squawking. Northwest has several other unions Delta will have to deal with, as well. The merger of nonunion management and support functions raises the angst level in any merger.

AIRPLANES: Delta and Northwest fly many of the same kinds of jets, but also have some different types. Most notably, Northwest uses jets built by Airbus as well as Boeing and McDonnell Douglas, while Delta is all-Boeing or MD. Delta will have to decide how to gain efficiencies in maintenance, which could involve dropping some models — though execs on Tuesday argued that the variety is a plus — and eventually cutting maintenance centers. Procedures and training also need to be standardized.

COMPUTERS: Think your company has IT headaches? Imagine stitching together systems that handle millions of inquiries and bookings every day, take payments and do airport check-ins. There are also systems to set fares, schedule flight crews and handle payroll and accounting for a 75,000-person company. The fact that both Delta and Northwest are clients (and former co-owners) of Worldspan, a Cobb County-based travel reservations services provider, could smooth the ride in some areas.

SERVICE: There are only so many ways to serve soda at 30,000 feet or smile and say "buh-bye," but airlines all have their own tweaks and subtle variations on dealing with customers at the airport and in flight. Customer service practices and training, along with product offerings, will have to be unified. One interesting twist: Delta, as you might expect of an Atlanta-based company, serves Coke products aloft. Northwest's complimentary soda? Pepsi.

MARKETING: The new Delta will be not just bigger, but better. At least that's the theme marketing execs will pitch to both consumers and all-important corporate and government travelers. Already the two carriers have a Web site, www.newglobalairline.com, devoted to the task, but there'll be much more work to be done in advertising and corporate sales. A big task will be raising the brand profile in Asia, where Northwest is long established but Delta is largely unknown.