As the weather warms up, our thoughts invariably turn to the threat posed by the city’s air conditioners and their occasional tendency to fall out of windows and land on humans. But let’s not forget that other, more obviously dangerous things can drop out of the sky and hit us, too. Luckily, the serrated tool that flew 100 feet from a construction site at 48th Street and Ninth Avenue only hit this woman in the leg — instead of, say, her head — but the incident is still a good reminder to stay alert, always.