The P-15 "Tropa" (Russian: "Тропа"; English: "trail") or 1RL13 (also referred to by the NATO reporting name "Flat Face A" in the west) is a 2D UHF radar developed and operated by the former Soviet Union.

[1] The P-15 was designed to detect aircraft flying at low altitude and came to be associated with the S-125 "Neva" anti-aircraft system (NATO reporting name SA-3 "Goa"), though it was later replaced by the P-15M2 "Squat Eye" radar which mounted a single radar antenna on a 20-30 meter mast to improve coverage.

In 1962, another modernisation of the P-15 passed through trials as the P-15N, the radar being developed and produced by the Ulyanovsk Mechanical Plant.

The P-15MN included a pulse coherent Doppler filter (moving target indicator) to remove passive clutter (by up to 50 dB),[1] the first such radar in the Soviet Union.

With the antenna mounted directly on the single truck (Zil-157) used for transport, the system could be deployed and taken down in no more than 10 minutes.