The foot (ft, ') is a unit of length in the international mass and length units.
Definition of the foot
One foot is defined as 1⁄3 of a yard.
From the Weights and Measures Act of 1985: Measurement of length
Value in terms of the SI
One foot is equivalent to 0.3048 meters.
The foot is another unit based on the human body. It has historically been used in multiple unit systems, namely the Greek, Roman, French, English and Chinese. Its size could vary a lot between those systems.
One foot is also equivalent to:
The Concorde service ceiling was 60000 feet, while most current commercial flights fly somewhere around 40000 feet. A very high cruise altitude was necessary to reduce drag and allow for supersonic speed.
The International Mass and Length Units
The International Mass and Length Units are units based on the international yard and the international pound.
They were created in 1959 when Australia, Canada, New Zealand, South Africa, the United Kingdom and the United States of America agreed upon a common definition of the yard and the pound.