Boarding a plane could soon become complicated for some in Maine.

The federal government has alerted Maine's secretary of state that time is up to bring state ID cards and drivers licenses up to Homeland Security standards.

If the state does not make changes to IDs by 2018, Maine residents will have to show an alternative form of identification, such as a passport, to board a commercial airplane.

The 2005 Real ID Law changed several requirements for state IDs, including photographs that can run through facial recognition software. The law also requires the state to scan and collect documents such as birth certificates.

In 2007, the Maine legislature decided against complying with the Real ID law.

"We have some profound concerns about the cost and effectiveness, and how you would safe guard privacy," said Maine Secretary of State Matt Dunlap.

Dunlap said it would cost Maine "millions" of dollars to make those changes to the ID cards.

Passengers flying out of the Portland Jetport were surprised and frustrated to learn about the situation.

"I think we should do the same as other states, and make it easy enough for the passengers," said Becky Marvil.

"It's crazy," said Anne Adams.

Passengers worried that they'd have to pay for a passport or not be able to fly come 2018.

"I'm sure it's going to be a big inconvenience for a lot of people," said Gail Brassbridge.

Maine is one of five states in the country out of Real ID law compliance.