Incorrect. The U.S. Department of Transportation's rules require airlines to allow passengers to bring aboard a carry-on of medical equipment, at no charge and without it counting against the carry-on allowance. Notably:
What mobility aids and other assistive devices may passengers with a disability bring into the aircraft cabin?
Passengers may bring manual, but not electric wheelchairs, other mobility aids (e.g., canes, including those used by blind passengers), and other assistive devices (e.g., POCs), as well as prescription medications and any medical devices needed to administer them (e.g., syringes, auto-injectors), as long as they comply with applicable safety, security and hazardous materials rules. These devices and aids cannot be counted against the airline’s carry-on limits.
Code of Federal Regulations, Title 14, Section 382.121 (
http://airconsumer.ost.dot.gov/rules/Part%20382-2008.pdf)
When may a bag containing an assistive device be counted towards a passenger’s carry-on bag limit?
An assistive device is any piece of equipment that assists a passenger with a disability to hear, see, communicate, maneuver, or perform other functions of daily life, and may include medical devices and medications. A carrier may count toward a passenger’s carry-on limit a carry-on bag containing items other than an assistive device. For example, a bag containing both medications related to the passenger’s disability and toiletry items or one in which a back brace and clothing are packed would be subject to the carry-on limit even though the medications and back brace meet the definition of assistive device. To the extent possible, all of a passenger’s assistive devices should be included in one bag. When making a determination as to whether an item qualifies as an assistive device, the carrier may ask the passenger how the item assists the person in performing a function of daily life.
Answers to Frequently Asked Questions Concerning Air Travel of People with Disabilities Under the Amended Air Carrier Access Act Regulation (
http://airconsumer.ost.dot.gov/rules/FAQ_5_13_09.pdf)