If you are physically disabled/handicapped/limited and ride a tadpole trike you may be eligible to travel via commercial airlines with your trike at no cost for the trike. Airlines charge a very large fee for transporting trikes so this could be very helpful. Here is an article about this subject …
http://bentwanderings.blogspot.com/2015/10/mobility-assistive-devise-operative.html
And here are a couple of articles about trikes being used by those with special needs …
http://www.3x365continue.com/blog/archives/01-2015
http://www.disabled-world.com/assistivedevices/mobility/scooters/3-wheel/horizon.php
Tadpole Rider 