 When the siren sounds, they pack on their gear and load onto a short C-23 Sherpa plane. We have about two minutes to get our jump gear on, and then we're boarded onto the planes in less than 10 minutes. Becoming a smokejumper isn't for the faint of heart. Candidates must be in top physical shape and have some firefighting experience. Their missions are often miles away from civilization, which is why they bring everything they need with them.