Definition
A Technical Standard Order (TSO) is a minimum performance standard issued by the FAA for specified articles of equipment used on civil aircraft. When a manufacturer receives TSO authorization, it means the article meets the FAA's required design and production standards for that piece of equipment, such as a GPS receiver, altimeter, or transponder.
Plain English
A TSO is an FAA-issued rulebook for a specific piece of aircraft equipment. If a unit is 'TSO'd,' the FAA has confirmed it meets the required standard for that type of gear.
Context Anchor
Seen in discussions of approved aircraft electronics and navigation equipment, including equipment requirements connected with instrument procedures and en route chart use.
Derivation
Technical' refers to equipment specifications. 'Standard' means a fixed requirement everyone must meet. 'Order' here means an official FAA directive. Together: an official FAA directive setting the technical standard for a piece of equipment.
Why Pilots Care
Only TSO-approved equipment satisfies regulatory requirements for IFR operations and airworthiness.
Intuition Check
Do not read this as “Technical Standing Order.” In FAA equipment approval language, TSO means “Technical Standard Order.” Also, a TSO approval applies to the item’s standard; it does not automatically approve every installation or every use of that item.
Example Sentence 1
The approach required a GPS unit certified to TSO-C145, so the pilot checked the avionics placard before filing.
Example Sentence 2
Before flight, the pilot verified that the transponder met the required TSO standard.