Blimps take to the skies in search of a singular goal: your eyeballs. Thursday morning, one did just that, for all the wrong reasons: A blimp cruising over the US Open golf tournament in Erin Hills, Wisconsin appeared to deflate and crumple, then caught fire and crashed in a plume of black smoke.
The pilot, the only person aboard, rode the wreckage to the ground (he didn’t parachute from the blimp, contract to early reports). He was taken to the hospital and is expected to recover, according to the company operating the blimp, Florida-based Air Sign. There’s no details yet on what caused the crash, but the National Transportation Safety Board has started an investigation.
The crash looks dramatic, but this is no Hindenberg. The Air Sign blimp, which was advertising a credit union at the time of its demise, belongs to a little-known variety of aircraft called the thermal airship, which is fancy talk for a football-shaped hot air balloon. It’s inflated and lifted by air heated with a propane-powered flame, controlled by the pilot riding in a gondola slung under the belly of the thing. The explosion of the propane tanks created the fireball when the wreckage was on the ground.
By contrast, the more famous, much larger Goodyear blimp uses a semi-rigid structure made from aluminum and carbon fiber, filled with lighter-than-air helium, and can carry 14 people. (Hydrogen hasn’t been used as a lifting gas for 80 years because it’s too dangerously flammable, as most famously seen in that Hindenburg disaster.)
Thermal airships offer a few advantages over fancier, helium-pumped aircraft. They can fold up small enough to fit into a small truck, for easy transport between events, and don’t need an airfield and hangar for operations. They’re also cheaper: The helium to fill even a small, two man, blimp costs around $ 10,000, versus a couple of tanks of propane to heat some air.
Flying on hot air has its downsides, too, chief among them a general lack of control. “You can steer it downwind, but they can hardly fly into the wind,” says Dan Speers of Ontario-based Mobile Airships, who has spent 20 years making and renting manned and unmanned blimps. Although the vessels have a propeller, the pilot can only steer about 60 degrees left or right of where the wind’s carrying them—typically enough to hover in the general area of an event for a day carrying advertising. The crashed blimp, a Gefa Flug AS 105GD, carries a 65-horsepower engine and can hit 30 mph in the right conditions.
That means a thermal blimp needs a chase team in a vehicle, to follow it on the ground and recover it wherever it eventually lands. A member of the chase team reportedly pulled the pilot from the wreckage Thursday.
The NTSB team is still working out what its investigation will require—blimp crashes are rare—but investigators will start by examining the wreckage and interviewing the pilot and witnesses. As ever, their focus will be on learning any lessons that can prevent another similar accident in future, and hopefully keep blimps in the air, with eyes on them for the right reasons.