The air pressure in the vicinity of the static port is conveyed by a conduit to the altimeter and the airspeed indicator.
The objective of the static system is to sense the pressure of the air at the altitude at which the aircraft is flying.
When deciding on a position for a static port, aircraft designers attempt to find a position where the error between static pressure and free-stream pressure is a minimum across the operating range of angle of attack of the aircraft.
Aircraft design standards specify a maximum amount of Pitot-static system error.
US Federal Aviation Regulations, Part 23,[6] §23.1325(e) includes the following requirement for the static pressure system: The error in indicated airspeed must also not be excessive.
Part 23, §23.1323(b) includes the following requirement for the airspeed indicating system: For the purpose of complying with an aircraft design standard that specifies a maximum permissible error in the airspeed indicating system it is necessary to measure the position error in a representative aircraft.