Consumer and trade organizations on Monday asked the U.S. Department of Transportation to require that airlines give a more complete accounting of baggage fees, change charges and other costs faced by air passengers.

The USDOT has proposed that  airlines and ticket agents be required to disclose fees that add to the cost of flying. The federal agency says fees for such things as checked luggage, carry-on items, and advance seat assignment “are often difficult to determine when searching for airfares and as a result, many consumers are unable to understand the true cost of travel before purchasing a ticket.”

Three organizations, The Global Business Travel Association (GBTA), the non-profit Travelers United, and an alliance of travel service operators know as Open Allies for Airfare Transparency, were among those who weighed in with formal comments Monday before the window closed for comments on the proposal.

“The lack of consistency and transparency in the pricing and application of ancillary fees in all categories of travel, but especially for air travel, is a major challenge for business travel managers,” said Michael W. McCormick of the GBTA.

Baggage fee revenue rose from $464 million in 2007 to $3.35 billion in 2013 and reservation change fees rose from $915 million in 2007 to $2.8 billion in 2013, the GBTA said.

Travelers United also asked the USDOT to mandate “publication of code-share flights, better reporting for lost luggage, clarification of travel website status and limits on post-purchase changes.”

“Ever since American Airlines became the first major airline to charge for checked baggage, the industry has been ‘fee happy,’ charging fees from everything from baggage and seat reservations to pillows and blankets, printing boarding passes and even to check-in for heavens sake,” said Travelers United Chairman Charlie Leocha.

In their filing, the Open Allies for Airfare Transparency said: “To achieve the Department’s goals of enabling transparency, comparative shopping and efficient purchasing, it is essential that ancillary fee information be provided to ticket agents in the same transactable format as fares. Ticket agents provide a comparative shopping experience for consumers that they do not receive from airlines.”

The trade group also told the USDOT, “The ability to easily compare prices and schedules allows consumers to make better-informed choices, saves substantial search costs, and leads to better product and price offerings for consumers. Consumers lose the benefits of the comparative shopping experience when they are unable to transact services using the indirect channel.