Over the weekend, a plane took off from Liberia, bound for the United States. On board was, along with a small group of medical personnel, Kent Brantly, 33, one of two Americans who became infected with ebola while working with victims of the virus in West Africa. Today, a second aid worker, Nancy Writebol, 59, is making the same journey. Their destination: Emory University Hospital, which features a containment unit—designed in collaboration with the Centers for Disease Control and Prevention—developed for treating patients with serious communicable diseases.
But how do you get these patients from Africa to Atlanta? How do you transport people who cannot transport themselves—who in fact require a group of healthy medical workers to facilitate the 12-hour trip—while keeping the highly contagious virus contained? How do you ensure that the healthy workers don't themselves get infected in the process?

It starts, Jalopnik's Foxtrot Alpha reports, with a 32-year-old Gulfstream III. Gulfstreams are typically business jets; this one, however, was formerly the property of the Royal Danish Air Force. It was sold, in 2005, to Phoenix Air, which provides military air support to the U.S. Department of Defense and specializes in, among other things, the outfitting of air ambulances. Phoenix Air's pair of planes—the company has another Gulfstream, currently based in Russia—are outfitted for medical emergencies just like the one facing Brantly and Writebol. The vehicle that has been transporting the two patients, Tyler Rogoway writes, is today "one of the most advanced and capable in the world."
What makes the plane particularly suited to intercontinental quarantine is its swiftness: It can travel long-haul routes at high speed, even with a relatively large medical team on board. But the other thing that suits the jet—which flies, for this mission, under the call sign Gray Bird 333—to its unusual work is its adaptability. For the flight from Liberia, the plane was outfitted with an Aeromedical Biological Containment System: a modular, tent-like plastic structure that uses a HEPA-filtered ventilation system to keep pathogens contained within it.
According to the protocol of the U.S. Army Medical Research Institute of Infectious Diseases, as reported by the Washington Post, the patients—who make the journey on stretchers—are likely accompanied by a doctor, a nurse, and four to six medics. Those personnel wear impervious suits—the kind you may recognize from movies like Outbreak—that feature hoods and vinyl boots. They communicate with the patient using two-way radios. They don't use sharp tools of any kind—to avoid the possibility of puncturing the tent—which means that they administer any drugs or fluids the patients require using a needle-less IV.

Despite all these precautions, the work is dangerous. Flights can be bumpy. Plastic can be punctured. (Ebola may not be airborne, but imagine being trapped in a flying tube with it.) And the danger can translate to patients, as well as their caregivers. As Thomas Frieden, the director of the CDC, put it during a press call, "There is the potential that the actual movement of the patient could do more harm than the benefit from more advanced supportive care outside of the country."
The Gulfstream III, the business jet transformed into a flying quarantine unit, tries to mitigate that risk.
