Which type of radar does not require a transponder (XPDR) and can locate weather?

The correct choice is based on the unique characteristics of different radar systems in aviation, particularly their capabilities concerning tracking and weather detection.

PSR, or Primary Surveillance Radar, operates by sending out radar signals that bounce off objects, including weather systems. PSR does not rely on aircraft transponders to function; it simply measures the time it takes for the radar signal to return after it strikes an object. This allows it to identify the presence of weather formations such as precipitation, which is essential for pilots to understand the current atmospheric conditions along their flight paths.

This capacity to detect weather is a significant advantage of PSR, making it an invaluable tool for air traffic control and weather monitoring. The absence of the need for a transponder means that PSR can provide information on non-transponding objects, such as severe weather phenomena, enhancing safety and operational efficiency.

In contrast, SSR (Secondary Surveillance Radar) does depend on transponders to receive specific information from aircraft, while ASR (Airport Surveillance Radar) is typically focused on monitoring aircraft in the vicinity of an airport and also works with transponders for enhanced data. Ground-based radar systems specifically have varied applications, but not all are designed for weather detection in the same way as PS