Airlines should disclose extra costs for accommodations like checking a bag when selling tickets, U.S. transportation regulators said today in a package of proposed consumer protections.

Added fees for changing seats, luggage and earlier boarding make up a growing portion of the costs of flying and those costs aren’t always obvious while buying a ticket, the U.S. Department of Transportation said.

“Knowledge is power, and our latest proposal helps ensure consumers have clear and accurate information when choosing among air transportation options,” Transportation Secretary Anthony Foxx said in an e-mailed statement.

The proposal would be the third air-traveler protection measure enacted under President Barack Obama and comes as airlines and some House members are attempting to overturn earlier consumer regulations.

Today’s proposal also requires some smaller airlines to begin submitting data on traffic and consumer issues, as is currently required of major carriers.

Airlines and the public have 90 days to comment on the proposal before the department begins finalizing the rule.