§ 250.2b Carriers to request volunteers for denied boarding. (b) Every carrier shall advise each passenger solicited to volunteer for denied boarding, no later than the time the carrier solicits that passenger to volunteer, whether he or she is in danger of being involuntarily denied boarding and, if so, the compensation the carrier is obligated to pay if the passenger is involuntarily denied boarding. If an insufficient number of volunteers come forward, the carrier may deny boarding to other passengers in accordance with its boarding priority rules.