PAR part of ground controlled approach.
A typical ground controlled approach.
The technique or procedure for “talking down” an aircraft during its approach to position it for landing. A radar approach system operated from the ground by air traffic personnel transmits instructions to the pilot by radio. The initial approach is conducted with surveillance radar (SRE [surveillance radar element] or ASR [airport surveillance radar]) and the latter, and the more crucial, part of the approach by precision approach radar (PAR). It is possible to conduct approaches solely with either ASR or with both ASR and PAR. However, the minimums with the former are not as stringent as the latter. Pilots should specifically request a PAR approach when they desire a precision radar approach or an ASR, or surveillance approach, when they desire a non-precision radar approach.