Glossary "T"

Temperature Gauge

The thermometer system, required in all type-certificated hot air balloons, that gives a constant reading of the inside air temperature at the top of the envelope. May be direct reading, or remote, using a thermocouple or thermistor connected to a gauge in the basket or reading signals sent by a transmitter.

Temperature Recorder

A small plastic laminate with temperature-sensitive paint dots that turn from white or silver to black, to record permanently the maximum temperature reached.

Tensile Strength

The strength of a material that resists the stresses of trying to stretch or lengthen it.

Terminal Velocity Descent

A term used by balloonists for the speed obtained when the balloon is allowed to fall until it apparently stops accelerating, at which point the envelope acts as a parachute and its vertical speed is no longer affected by its lifting gas, but only by its shape (which is caused by design), load, and other factors.



Operation of a manned balloon secured to the ground by a series of lines.


A large triangular-shaped wind indicator mounted on a pivot so it can swing free and point into the wind. Usually found at airports.


A column of rising air associated with adjacent areas of differing temperature. Thermal activity caused by the sun's heating usually starts 2 to 3 hours after sunrise.

Throttle Valve

See Blast Valve.

Time in Service

"With respect to maintenance time records, means the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing." (14 CFR part 1)


Touch-and-Go Landing

An operation by an aircraft that lands and takes off without stopping.

Traffic Pattern

The traffic flow that is prescribed for aircraft landing at or taking off from an airport.

Turning Vent

A vent on the side of a hot air balloon envelope which, when opened, allows escaping air to exit in a manner causing the balloon to rotate on its axis.

Type Certification

Official recognition that the design and operating limitations of an aircraft, engine, or propeller meet the airworthiness standards prescribed by the Code of Federal Regulations for that particular category or type of aircraft, engine, or propeller.

Uncontrolled Lift

Lift that occurs without specific action by the pilot. Often referred to as false lift.


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