Darkening skies

What began as a border conflict has now turned into a dispute about airspace. Beginning Saturday (13.10.2012), Syria declared that Turkish planes must not enter its skies. The Turkish government responded by banning Syrian aircraft from entering its airspace.

On Wednesday, the Turkish government forced a Syrian passenger plane en route from Moscow to Damascus to land in Ankara. Turkey said the move was motivated by suspicions from Turkish intelligence that military equipment may have been on board the flight. The Airbus A-320 was intercepted by Turkish F-16 fighter jets. Prime Minister Recep Tayyip Erdogan then claimed that Turkish authorities had found military gear on board, but the Russian government has denied these claims. Russian Foreign Minister Sergey Lavrov said the plane was carrying a legal delivery of radar parts.

During a visit to the Turkish capital, German Foreign Minister Guido Westerwelle offered support to the government's move.

"Turkey does not have to tolerate the transmission of weapons to Syria through its own airspace," he said. "If such a situation were to occur in Germany, we would have done the same thing."

However, Westerwelle also urged both parties in the conflict to show discretion.

Airspace treaty

"The airspace above a state belongs to that state," said Elmar Giemulla, an expert on aviation law at Berlin's Technical University.

International law permits states to dictate who can fly over their territory and what cargo they are allowed to carry - on both civilian and military flights.

Turkey and Syria agreed in 1944 to allow one another access to the skies without requiring any special permission - but only for civilian flights, said Marcus Schladebach, an expert on aviation and space law at the University of Kiel. He noted that the intercepted Syrian flight involves the core question of whether the radar equipment found on board is in fact a military or a civilian device.

If the flight was indeed carrying military cargo, then it does not fall under the countries' treaty and would have required flight approval.

Special rules on passenger flights

When planes cross into another country's airspace without permission, the country in question is to contact the aircraft's operator. Then interceptor planes can be sent to give the pilot notice that he must leave the airspace or follow the fighter jets. If the incoming flight does not react, then the plane can be forced to land - as happened in the case of the Syria-bound plane.

"That's where it gets critical," said air expert Elmar Giemulla. If the incoming pilots are not compliant, the situation can quickly turn dangerous. But Giemulla points out that it's not yet known whether Turkey followed the entire protocol before forcing the Airbus to land.

There is a clear line, however, when it comes to passenger planes, Marcus Schladebach points out. Weapons cannot be used against them, a regulation adopted after a Korean passenger flight was shot down in 1983. The plane had gone off course and was shot down by Russian interceptors over the Soviet island Sakhalin. The Russian military mistook the aircraft for a spy plane, and all 269 passengers were killed.

Harsher stance on military

The rules are different when it comes to military planes and helicopters, which can be shot down once they pass into foreign airspace without permission, says Elmar Giemulla. But, he adds, such actions have to take place within reasonable bounds, and that also goes for international airspace over the ocean and beyond particular states' sovereign territory.

In June, Syria shot down a Turkish fighter jet, saying it had crossed into Syrian airspace. The move set off a conflict between the Syrian and Turkish governments that has escalated in recent weeks. Turkey was once an ally of the Assad regime but now supports the opposition. On Friday (12.10.12), Turkish fighter jets pushed a Syrian military helicopter out of a border area.

The block on Turkish air traffic over Syria means Turkish pilots have to look for new routes, but the restrictions do not apply to other airlines.