Definition
An additional category rating added to an existing pilot or flight instructor certificate that authorizes the holder to act as pilot or instructor in gliders. The applicant must meet the FAA's aeronautical knowledge, flight proficiency, and experience requirements specific to gliders, and the rating is issued by endorsement and practical test rather than by issuing a new certificate.
Plain English
It's an extra rating added onto a pilot or instructor certificate someone already holds, giving them the legal authority to fly or teach in gliders.
Context Anchor
Seen in endorsement records, training plans, and practical test preparation when a pilot or instructor is adding glider privileges to an existing certificate.
Derivation
Add-on' simply means something added to what already exists. In FAA usage, it refers to adding a new category or class rating to a certificate the pilot already holds, rather than starting fresh with a new certificate.
Why Pilots Care
It expands a pilot's privileges to unpowered aircraft without requiring an entirely new certificate.
Intuition Check
Do not read “add-on” as an informal extra or optional bonus. Here it means an official added privilege on an existing FAA certificate, with required training, instructor approval, and testing.
Example Sentence 1
After earning his private pilot certificate in airplanes, he pursued a glider add-on so he could fly at the local soaring club.
Example Sentence 2
With the glider add-on now on his private pilot certificate, he could rent and fly the club sailplane.