(CNN) -- Airlines and ticket agents would be required to disclose fees for checked bags, carry-on items and advanced seat assignments under new rules proposed by the U.S. Department of Transportation on Wednesday.
The rules would require those ancillary fees be disclosed to consumers as they are comparing fares.
"Knowledge is power, and our latest proposal helps ensure consumers have clear and accurate information when choosing among air transportation options," said U.S. Transportation Secretary Anthony Foxx, in a press statement.
"The proposal we're offering today will strengthen the consumer protections we have previously enacted and raise the bar for airlines and ticket agents when it comes to treating travelers fairly," Foxx said.
Internet search sites such as Kayak and Google would be defined as "ticket agents" and fall under the department's new consumer protection requirements, the agency said.
Spirit Airlines and other smaller airlines would also be required to report their on-time performance data, mishandled baggage rates and overbooking. That's under the proposed requirement that any airline accounting for at least 0.5% of domestic scheduled passenger revenue report that data, versus the current 1% requirement.
Other items in the proposal:
Larger travel agents must adopt minimum customer service standards, including quick responses to customer complaints and allowing customers to hold quoted fare reservations without payment or to cancel without penalty for 24 hours provided the reservation is made a week or more before departure date.
Airlines and ticket agents must disclose any code-sharing arrangements on initial itinerary displays on their websites. For example, a United Airlines or Delta Airlines reservation that includes a regional carrier flight would need to identify the regional carrier.
Ticket agents that give preferences to certain carriers over others, whether in their schedules, fares or availability, must disclose their bias.
The government is accepting public comments on the proposed rule for 90 days. The proposed rule can be found online at
Airlines fight back against listing full prices
The airlines have fought back against one of the agency's earlier consumer protection rules -- the so-called "full fare" requirement -- which requires airlines and ticket agents to show a ticket price that includes all mandatory fees and taxes.
Airline officials claim that requirement allows the government to hide the full extent of its taxation, which can run about 20% of the ticket price, according to Airlines for America, an industry trade group. Airline allies in Congress have introduced the "Transparent Airfares Act of 2014" to roll back that "full-fare" requirement.
But airline passenger advocates argue that by trying to repeal the existing "full-fare" rule, the airlines are simply trying to hide the true cost of their tickets. A counter-proposal to keep the existing regulations, the "Real Transparency in Airfares Act," has been introduced in the U.S. Senate.
Earlier consumer protection rules have also drastically reduced tarmac delays of more than three hours, the transportation department said. Faced with fines for delays, airlines have canceled flights or otherwise figured out how to reduce delays. The earlier rules also grant passengers more compensation when involuntarily bumped from oversold flights.
The new proposals are long overdue, says travel blogger Johnny "Jet" DiScala, "and will make a huge difference when consumers go to book flights since they will know exactly how much it's going to cost."