Passenger service unit
Aircraft component
From Wikipedia, the free encyclopedia
A passenger service unit (PSU) is an aircraft component situated above each row in the overhead panel above the passenger seats in the cabin of airliners. Among other things, a PSU contains reading lights, loudspeakers for announcements, illuminated signs (to remind people that the cabin is a no-smoking zone and to wear a seatbelt), buttons to call for assistance (though these are mounted on the armrest on some aircraft), air condition vents, and automatically deployed oxygen masks in case of cabin depressurisation.[1]
May be absent or simplified on the smallest regional aircraft or on some very early-generation airliners [2]
