Final answer:
An ASR or PAR approach can be affected by rain due to interference with the radar signals, leading to reduced accuracy and visibility.
Step-by-step explanation:
An ASR (airport surveillance radar) or PAR (precision approach radar) approach can be affected by rain. Rain can cause interference with the radar signals, leading to reduced accuracy and visibility.
When rain is present, the radar waves can be scattered or absorbed by the rain droplets, resulting in a weaker signal reaching the radar system. This can make it difficult for the radar to accurately track the aircraft's position and altitude, potentially affecting the precision of the approach.
In extreme cases of heavy rain or thunderstorms, the radar signals can experience even greater interference due to the large amount of water in the atmosphere. This can make it unsafe or impossible to conduct an ASR or PAR approach.