An aircraft lavatory is a small room on an aircraft with a toilet and sink. Lavatories provided aboard aircraft vary considerably from airline to airline and aircraft to aircraft. Normally accepted minimum ratio of lavatories to passengers is approximately one lavatory for every 50 passengers. However, in premium cabin and business cabins, passengers may have access to multiple lavatories reserved primarily for their use. These ratios of lavatories to passengers vary considerably, depending upon which airline is being used with some first class passengers having one lavatory for every 12 passengers. Additionally, many of the larger long-haul airlines elect to equip their aircraft with larger lavatories for this particular group of passengers willing to pay higher fares. Standard fixtures in the lavatory are as follows:
Built in waterless toilets with push button flush
Call button - for assistance
Electrical outlet
Garbage can
Handle bars to assist elderly or disabled passengers to get up from toilet
Hand-wash faucet and sink
Mirror
Paper towels
Soap dispenser
Toilet paper dispenser or linens
Paper cup dispenser
Sign on door to indicate lavatory in use or not in use
Fitted cabinets may contain additional toilet paper and other toiletries, but they are often locked. The toilet and sink are often moulded plastic or a stainless steel sink, the floor is usually a non-slip surface. In newer aircraft, the executive or first class lavatories are roomier and offer more toiletries and other comforts.
The presence of an ashtray in the toilet is sometimes commented upon, given that smoking has been long banned on flights in many parts of the world. However it is a requirement of the Federal Aviation Administration that ashtrays continue to be fitted to the doors of aircraft toilets. This is due to the fire risk caused by the possible disposal of illicitly consumed smoking materials in the toilet's waste bin.
Waste bins are fitted with halon fire-extinguishing bottles and "oxygen-smothering" "flapper lids", and the toilets equipped with smoke detectors. Over time these protective devices have been incorporated into aircraft lavatory designs due to fires that have started when the careless smoker of the past or the clandestine smoker of the present has incorrectly disposed of smouldering smoking material. If the toilet's fire extinguishing system is inoperative, the aircraft is still permitted to fly, provided the toilet is barred to passengers and only used by crew members.
Types of aircraft lavatories: Lavatories on modern aircraft are very expensive, and include features that have required substantial upfront and long term investments by the world's airlines to design and develop. Airlines and aircraft manufacturers continue to investigate ways to improve lavatory design technology to increase functionality and reduce costs of production, while maintaining adequate levels of safety, hygiene and amenity. For this reason many modern lavatories are now no longer of the "chemical toilet blue water re-circulated electric flush" variety. Instead lavatory manufacturers have progressed to "vacuum flush" technology to eliminate solid and liquid residue from the basin.
Some of the advantages of "vacuum flush technology" systems, from aircraft designers’ perspective, is the increased safety attributes through less risk of corrosive waste "spill over" into recesses around the lavatories which can be difficult to protect. Additionally, "vacuum flush systems" are considered to be less odor-inducing and substantially lighter which bear substantial fuel savings by way of reducing the need to carry excessive "blue re-circulating water" as in the past.
Lavatory agents: Each aircraft equipped with a bathroom or lavatory needs to expend its waste somehow. This is where the lavatory or "lav" agent comes in. After an inbound aircraft arrives it is the lav agent's job to flush the lavatory system. In stations with higher volumes of passenger traffic, lavatory agents will usually utilize trucks adapted with large tanks on board that do not need to be emptied as often. These are also configured to facilitate access to the waste ports of the aircraft, which can be out of reach by other means. In places where fewer or smaller aircraft are being serviced a "lav cart" (essentially a small lav truck pulled behind a tug) is used to service the lavatories.
