An airplane "aisle chair" is a mobile seat provided by airlines for passengers who require the use of a wheelchair. While most trains, buses and other forms of public transportation have space for a passenger's own wheelchair for seating and a ramp or lift assist for boarding, airplane aisles are too narrow for conventional wheelchairs. The aisle chair affords the wheelchair passenger assisted mobility in boarding and disembarking, and in-flight moving within the cabin such as to the lavatory.[19]