Air carriers shall prohibit smoking whenever the ventilation system is not fully functioning. Fully functioning for this purpose means operating so as to provide the level and quality of ventilation specified and designed by the manufacturer for the number of persons currently in the passenger compartment.
source: Docket No. DOT-OST-2000-7473, 65 FR 36775, June 9, 2000, unless otherwise noted.
cite as: 14 CFR 252.9