The “bird-dog” was an extremely slow, cheap, lightweight and small and lightweight civilian air plane, and although cheap, it was known for being extremely slow. It was unarmed (or almost unarmed) for the most part and was often used in a support role for SOG ground soldiers.
Given its ability to fly very low and slowly, it was used to locate hidden structures like radio relay sites, give info to ground soldiers and occasionally even for battlefield observation from up above or correct the nearby artillery’s aim throughout the fight.
Some of its pilots showed so much skill and subject to such levels of danger to became real and proper living legends.
In the above photo, an F4 Phantom strikes after receiving the coordinates from a ‘bird dog' airplane.