49 CFR Part 27 - Nondiscrimination on the Basis of Disability in Programs or Activities Receiving Federal Financial Assistance (with amendments issued through Aug. 2015)

(f) When level-entry boarding and deplaning assistance is not required to be provided under paragraph (e) of this section, or cannot be provided as required by paragraphs (b), (c), and (d) of this section (e.g., because of mechanical problems with a lift), boarding assistance shall be provided by any available means to which the passenger consents. However, hand-carrying (i.e., directly picking up the passenger's body in the arms of one or more carrier personnel to effect a level change the passenger needs to enter or leave the aircraft) must never be used, even if the passenger consents, unless this is the only way of evacuating the individual in the event of an emergency.