The agency's resources are simply overwhelmed and UAVs do not fit neatly into existing procedures and protocol.
"The issue is that as of today there are no formal rules set for unmanned aircraft, only rules for manned aircraft," Argrow says. The technology has leapt ahead of bureaucracy and the FAA finds itself asking UAV flyers to comply with rules that border on comical in this context, such as ones dealing with seat belts.
Of course, the FAA requirements are for security and safety: Terrorists or anyone for that matter could hijack a UAV, and a UAV increases the chances of midair or even ground collisions with other aircraft, buildings or humans.
Still, the battery-powered Tempest is relatively tiny, about three meters long with a 3.2-meter wingspan.* It can fly for an hour on one charge at up to 130 kilometers per hour. Researchers hand launch and guide it into areas three to five kilometers away from a developing supercell where it can handle up to 95 kph winds. Sensors on the Tempest's body measure pressure, temperature and moisture in a storm's downdraft inflow—the two airstreams that feed a tornado—and the UAV transmits in-flight data back to the team just in case it gets ripped apart by sudden gusts.
What is the risk?
It is tough at this point to pin down the real risk that UAVs present, but they certainly do not maneuver like conventional aircraft.
"Currently, no technology allows these planes to sense other aircraft and make turns to avoid it," says Les Dorr, an FAA spokesperson. The single most important criterion for any unmanned plane is to be able to "see and avoid" other aircraft, he adds.
UAVs may only weigh 5.5 kilograms but can still cause serious damage if they collide with piloted aircraft. For instance, the Canada geese that flew into the engines of US Airways flight 1549 resulting in an emergency landing on the Hudson River in 2009, weighed about 8 kilograms each.
Still, some VORTEX 2 scientists wonder just how high the risk is for a UAV to collide with another aircraft. "There will never be a sane human pilot in that area of the storm," says Erik Rasmussen the co-lead principal investigator for VORTEX 2. "I suppose a nutso crop duster guy could fly, but the odds are so miniscule relative to how many hoops we must jump through to get permission."
In order to get permission for Tempest flights the FAA required that during flight continuous visual and radio contact be maintained with the UAV, so the team built a computer that instructed the drone to follow a vehicle on the ground below it. "[It is] a bit ironic that we have an aircraft whose primary limitations are the capabilities of a ground vehicle," Argrow wrote in an e-mail.
The FAA had allowed for a manned "chase" aircraft to accompany the UAV. "But we didn't want people to be that close [to a tornadic storm]. It's dangerous," says Jack Elston, a graduate student in aerospace engineering at C.U.–Boulder. After all, "unmanned" is the entire point.
Last-minute flight maps
The FAA also demands a preplanned flight map submitted 48 to 72 hours prior to launching the Tempest. The irony of this requirement is painful: If the National Weather Service's Storm Prediction Center could provide 72 hours notice of where a tornado will form and where it will travel, drones would not be needed to study tornadoes in the first place. Right now, the best meteorologists can do is provide a 13-minute advance warning. This is the very reason VORTEX 2 and the Tempest UAV exist—the project's goal is to extend the warning times.
But when Argrow and his team started operations in early May, the FAA air traffic controllers quickly learned that their mandated rules simply did not work with a UAV tasked to catch fast-developing supercells. The Tempest team had been forced to submit numerous flight plans simultaneously—one for each of the 10 or 20 permitted land blocks they might cover while tracking storms 72 hours out—and this overwhelmed the controllers. The FAA realized they would need to reduce the 72-hour lead time, so the flight plans could be based on more recent meteorological information and thus be more precise, asking for access to only two blocks of land at any one time.