Only specific US air carriers require pilots to use TSO certified headsets. A technical standard order (TSO) is a minimum performance standard for specified materials, parts, and appliances used on civil aircraft. TSO authorisation means a company is authorised to manufacture a material, part, or appliances to TSO standards. When a company receives a TSO authorisation, the products meet the minimums for both design and production.Receiving a TSO authorisation is not an approval to install and use the authorised article in the aircraft.