passenger service unit

A passenger service unit (PSU) is an aircraft component situated above each row in the overhead panel above the passenger

seats A seat is a place to sit. The term may encompass additional features, such as back, armrest, head restraint but may also refer to concentrations of power in a wider sense (i.e " seat (legal entity)"). See disambiguation. Types of seat The ...

in the cabin of

airliner An airliner is a type of airplane for transporting passengers and air cargo. Such aircraft are most often operated by airlines. The modern and most common variant of the airliner is a long, tube shaped, and jet powered aircraft. The largest ...

s. Among other things, a PSU contains reading lights,

loudspeakers A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...

for announcements, illuminated signs (to remind people that the aircraft is a no-smoking zone and to wear a

seatbelt A seat belt, also known as a safety belt or spelled seatbelt, is a vehicle safety device designed to secure the driver or a passenger of a vehicle against harmful movement that may result during a collision or a sudden stop. A seat belt reduce ...

), buttons to call for assistance (though these are mounted on the armrest on some aircraft), air condition vents, and automatically deployed

oxygen masks An oxygen mask is a mask that provides a method to transfer breathing oxygen gas from a storage tank to the lungs. Oxygen masks may cover only the nose and mouth (oral nasal mask) or the entire face (full-face mask). They may be made of plastic, ...

in case of cabin depressurisation. These are not found on the smallest of feederliners, or on older aircraft. Safety equipment Aircraft cabin components {{aviation-stub