While fliers stand in serpentine security lines at the Atlanta airport’s domestic terminal these days, the international terminal a short distance away is a sparkling oasis with wide open space and few crowds.

Security waits at the 4-year-old complex are often less than 15 minutes. And it’s possible for any flier — under certain key conditions — to enter through the less-crowded international terminal and take the plane train to a domestic concourse.

The airport and Transportation Security Administration officials, however, recommend against it.

“We’re not advising [travelers in the domestic terminal] to go to the international terminal,” Hartsfield-Jackson International spokesman Reese McCranie said.

The main reason: TSA plans its international terminal checkpoint staffing based on the number of international flights. If a wave of domestic passengers starts using the terminal as a short cut, that will throw off staffings.

“Your line may actually be longer at international,” McCrainie said.

Lines still form at the international terminal security checkpoint, which has fewer lanes, during peak times for international travel. That’s usually in the afternoon when many overseas departures are scheduled.

Still, using the international terminal for domestic flights has been a not-so-hidden secret of frequent travelers since the new terminal opened in 2012.

Less savvy or experienced travelers could run into trouble, however.

For starters, the international terminal has a separate entrance, off I-75 as opposed to I-85 for the domestic terminal.

And airlines that do not operate international flights from Atlanta, such as American, United, Frontier and Spirit, do not have check-in counters there. Passengers on those airlines would only be able to bring carry-ons, and they’d need a pre-printed boarding pass.

Passengers who do check bags at the international terminal and park there will face an extra leg when they return on a domestic flight. After picking up their bags at the domestic terminal, they’d need to catch a shuttle to get back to their car at an international terminal garage.

There’s less parking at the international terminal, and only hourly parking is within walking distance. Daily parking requires a shuttle ride. Finally, the international terminal has less-convenient connectivity to some off-airport lots and to MARTA.

Could the international terminal someday act as a general second entrance to the world’s busiest airport, and become a solution to congestion at the domestic terminal? Airport officials are not keen on the idea.

“It is far less efficient to split your workforce,” McCranie said. “You wouldn’t be able to process a high volume of passengers in a quick and efficient way.”