The FAA continues to warn both rotary- and fixed-wing pilots of the danger posed by communications and meteorological towers being erected across the U.S. According to a 2012 American Wind Energy Association report, more than 45,000 wind turbines alone are now operating in the U.S., many less than 200 feet in height.
Towers less than 200 feet above the ground are not required to have lights, so they can create a significant safety hazard for low-flying aircraft. The risk increases because many of these towers are poorly marked and often occupy tiny pieces of real estate that make them and their associated support cables extremely difficult to identify from the air.
The FAA says towers can be erected in hours, which means pipe and powerline patrol pilots may find an obstruction in a field that was empty a day or two earlier.
The Professional Aerial Applicators’ Support System suggests pilots remain at least 500 feet agl during routine flights except when a descent below that altitude is absolutely essential.