On Tuesday, Bolivia – backed by Nicaragua, Ecuador and Venezuela – called the move against Morales’ plane an “act of aggression” and called on the Organization of American States to approve a declaration demanding that such an incident never be repeated. But while officials in Italy, Spain and France have backed away from embracing what took place – France called it a “technical” error, and Italy and Spain have denied they barred Morales’ jet – the lesson is clear.

“I would think it’s very instructive and worrisome for Snowden,” said a U.S. aviation expert, speaking on condition of anonymity because of the high political sensitivities surrounding the case. “Those states were on absolutely firm legal ground to deny (Morales) use of their airspace. Politically? That’s a judgment call.”

The aviation expert said flights fall into two main categories. The first is civil, such as most commercial and charter airlines, as well as postal services such as FedEx. The other category is state flights, which would cover military, police and aircraft such as Morales’ or President Barack Obama’s Air Force One that are used by governments.

Going the state flight option would require one of the Latin American countries to send a government plane and arrange for diplomatic clearance all along the way – a long shot with no ironclad guarantee of safe passage for Snowden.

If Snowden takes a regularly scheduled commercial flight out of Moscow, any country it flies over could order it to land.

And finding a path that doesn’t overfly a U.S.-friendly country is nearly impossible. A blogger for the Washington Post made a stab at coming up with such routes this week, including one that would carry Snowden to Iran and then Africa. All the routes were dubious and risky, the blogger concluded.

“He’s in a pickle,” the aviation expert said, adding that he couldn’t recall a similar case in his long career in the industry. “He’d want to be sure that every country he’s flying over or refueling in wouldn’t arrest him.”

And lurking under all the problems with air travel is another logistical kink: Snowden’s lack of travel documents. His U.S. passport was revoked, so it’s unclear how he’d be processed out of Moscow. In other asylum cases, those not involving fugitives accused of revealing state secrets, refugees have traveled on specially issued United Nations passports, or other temporary documents issued by individual countries.

One factor in his favor, analysts say, however, is the shrewd way Snowden appears to be using his revelations in his case for sanctuary. While governments might expect and forgive the United States for its global surveillance dragnet, ordinary people all over the world have expressed outrage at the program’s scope and targets.

Snowden has leaked damning information about the U.S. spying on China, the European Union and Latin American nations – all places that are instrumental to his safe passage. In deciding whether to ground a plane that might be carrying Snowden, experts said, nations would have to weigh bilateral relations with the United States against the folk-hero status Snowden enjoys among many of their own citizens.

“Everyone wants plausible deniability,” said David Gomez, a former FBI assistant special agent-in-charge and counterterrorism program manager who retired recently after nearly three decades at the agency. “The other nations might assist us, but nobody wants the award for helping us nab Snowden.”

Schofield reported from Berlin, Allam from Washington. Curtis Tate contributed from Washington.