There are flare boom and then there are flare booms. High Island 264, which is a compressor station in the pipeline system, has a flare boom that has its own platform. When a slug of liquid hydrocarbon hits, and is sent to the flare and lit, it can light up the sky for many miles. That flare has melted windshields and windows of aircraft parked on the quarters platform, several hundred feet away. You do not want to fly over that flare, ever, lit or not, because it lights automatically, and cannot be stopped. I have seen flames going hundreds of feet into the air from it. Most pilots avoid flare booms instinctively, because you never know what might come from them, or when. The heat from some can definitely affect the flight of an aircraft, and the gases from unlit booms have caused exceedances on many aircraft over the years, because essentially a large amount of extra fuel, which the fuel control knows nothing about, is suddenly sent into the engine. I stay away from them, and never get close while downwind of them.