One divided Mediterranean island. Two air traffic control centers that don't communicate. Tens of thousands of airline passengers flying popular tourist routes. That potentially disastrous math hovers over Cyprus every day.
Confidential reports by international aviation authorities obtained by The Associated Press warn of "a high risk of accident" in the airspace where Greek Cypriot and Turkish Cypriot air controllers give overlapping and contradictory instructions, confusing pilots on increasingly busy routes. The AP has uncovered details of four near misses in a large swath of Cypriot airspace sandwiched between Turkey and Egypt.
The most serious of those incidents, involving an Airbus 330 passenger jet and a cargo aircraft in October 2008, could have resulted in a mid-air crash, according to a senior official with the Cyprus Civil Aviation Department. There were at least three other near misses between June and October 2006 in which competing flight instructions brought aircraft close enough for their onboard collision avoidance system to activate, according to a confidential document.
The airspace is crisscrossed hundreds of times a day by flights between Europe and the Middle East.
Turkish Cypriots in the breakaway northern part of island have operated their own air control center since 1977 and lay claim to about a quarter of the 175,000-square-kilometer (67,570-square-mile) Nicosia Flight Information Region, or FIR.
World aviation authorities recognize only Nicosia Air Control Center _ in the internationally recognized Greek Cypriot south _ as having control over Nicosia FIR. But the Turkish Cypriot air traffic controllers have been issuing unauthorized flight instructions anyway _ instructions that many pilots unfamiliar with the island's complicated politics have been following.
Air traffic controllers on both sides are able to listen in on each other's chatter with pilots as a means of guarding against disaster. But they don't communicate directly.
"Yes, there is something that actually endangers flight safety, but it is controlled and nobody takes it to the extent that it would actually cause an accident," said Ayda Soylu, the foreign ministry director general in the breakaway Turkish Cypriot north.
International aviation officials have long acknowledged that the problem is compromising flight safety. But the extent of the danger has been unknown to all but a small circle of officials and aviation experts because no serious incident has ever been publicly disclosed.
A confidential European Commission briefing memo states that both the International Civil Aviation Organization, the U.N.'s global aviation body, and the International Air Transport Association, which represents 230 airlines worldwide, see the problem as containing the seeds of disaster.
"IATA believes that there is a high risk of accident in the region in the present situation," says the internal memo dated Nov. 3, 2008. "ICAO has also stated that all the ingredients are laid for an accident to happen."
Another body that represents airline pilots worldwide considers the northern part of Nicosia FIR as "critically deficient" because of the confusion sown by conflicting instructions.
IATA declined AP requests to comment on the issue. ICAO spokesman Denis Chagnon denied the European Commission memo reflected the official position of his organization. But he said that his agency recognizes only Nicosia FIR and double communications "can indeed negatively impact aviation safety."
He added that international aviation officials have "developed and promoted procedures that pilots in the region should follow to ensure the safety of air operations."
Aviation analysts say that Cyprus poses a unique safety risk.
"It's unprecedented to have competing or conflicting flight instructions that have resulted in many near misses over the years," said Bill Voss, president of the Flight Safety Foundation of Alexandria, Virginia.
Voss said that even an air traffic dispute between longtime rivals China and Taiwan over the Taiwan straits "has been managed more effectively than Cyprus." Voss said recent agreements on cross-strait flights have resolved the Asian dispute.
Voss has appealed to American authorities to help resolve the Cyprus air traffic dispute.
"A number of the airlines involved are code-share partners with U.S. carriers. It is logical to assume American citizens are being exposed to an unacceptable level of risk," Voss said in a March 23, 2009, letter to Frank C. Urbancic, the U.S. ambassador to Cyprus. The matter did not go any further.
On Oct. 22, 2008, a Turkish Cypriot air traffic controller's flight instructions led a Monarch Airlines flight carrying an unspecified number of passengers from Manchester, England, to the Cypriot coastal resort of Paphos to nearly crash with an Egyptian cargo plane, according to a senior Greek Cypriot aviation official.
Flying at a busy air traffic junction over the Mediterranean about 60 nautical miles south of Antalya, Turkey, the Airbus 330 pilot was told to lose altitude, taking the plane directly into the path of the Egyptian aircraft 2,000 feet (610 meters) below, according to the official, who spoke on condition of anonymity because of the sensitivity of the issue.
A Greek Cypriot air traffic controller at Nicosia Air Control Center monitoring both aircraft on radar noticed the mistake and immediately told the Monarch pilot to stop his descent, the official said.
The two planes missed each other by "a couple of hundred feet," close enough for the Egyptian aircraft's onboard collision avoidance alarm to warn pilots that a collision was only 30 seconds away, according to official documents shown to the AP. The Turkish Cypriots have declined to comment on any instances of near misses.
Experts point out that Cyprus' already busy skies are getting busier _ making it an ever greater challenge to keep track of flights.
The Nicosia FIR airspace sees about 850 commercial flights on an average day and as many as 1,000 on peak days, according to Europe's air safety agency EUROCONTROL. About a third of those go through airspace claimed by the Turkish Cypriots. Regional air traffic is projected to grow at around 3.7 percent annually over the next seven years, especially from fast-growing airlines in the Middle East and the burgeoning traffic of private jets.
A report detailing incidents inside Nicosia FIR shows that the October 2008 near miss was preceded by at least three other incidents between June and October 2006 in which overlapping flight instructions brought aircraft so close that the onboard collision avoidance system _ or TCAS _ activated.
In an April 25, 2006, incident, one plane cruising at 35,000 feet (10,670 meters) had to climb rapidly after a TCAS alert to avoid another plane coming from the opposite direction.
"I believe the other A/C (aircraft) may have been confused about his climb clearance. The requirement to communicate with 2 separate ATC (air traffic control) units is inherently dangerous and unsafe," said the unnamed author of the report.
Dangerous incidents continue to occur regularly, illustrating the ongoing risk to flight safety.
On June 12 this year, a TRA Boeing 737-800 flying from Amsterdam to Paphos was instructed by air traffic controllers at the Turkish Cypriot north's Ercan Airport to start descending from its cruising altitude of 39,000 feet (11,890 meters). It was at the same busy air traffic junction south of Antalya where the Monarch Airlines near miss occurred.
According to a Nicosia FIR report provided by the Greek Cypriot aviation official, the pilots ignored Nicosia air traffic controllers' attempts to contact them _ even on an emergency frequency _ and verify their intended flight level. That prompted Nicosia controllers to notify a Moscow-bound NWS Boeing 737-200 flying through the same air corridor in the opposite direction to be on alert for the inbound aircraft.
On April 7, a Beirut-bound Air France 777 flying off Cyprus' northeastern coast was cleared by Turkish Cypriot air traffic control to descend to 19,000 feet (5,790 meters), putting it in the flight path of a Rome-bound military transport plane flying from an unnamed Middle Eastern country, the Greek Cypriot aviation official said.
Again, Nicosia Air Control Center halted the Air France jet's descent to allow the military plane to pass 1,000 feet (305 meters) below.
"Conflicting or overlapping flight instructions have resulted in some serious incidents in the past, but fortunately, Nicosia ACC controllers ... intervened to prevent the worst," said Cyprus Foreign Minister Erato Kozakou-Marcoullis.
Nicosia ACC chief Haris Antoniades said "much time and effort" is spent to keep the situation from getting out of hand, raising stress levels for his 70 air traffic controllers.
According to Antoniades, there were 100 instances in 2009 in which aircraft flying through Nicosia FIR deviated from Nicosia ACC flight instructions because of Turkish Cypriot interference.
The problem stems from the 1974 division of the island along ethnic lines after Turkey invaded in response to a coup by supporters of union with Greece.
Turkish Cypriots declared an independent republic in the north recognized only by Turkey. They also claimed a roughly 47,000-square kilometer (18,147-square mile) patch of Nicosia FIR over the island's northern half and the Mediterranean that they named Ercan Advisory Area.
Some 42 Turkish-trained air traffic controllers work at the north's air control center next to Ercan Airport, some 20 kilometers (12 miles) east of the capital Nicosia. However, ICAO, the U.N. aviation body, advises pilots to comply only with Nicosia ACC flight instructions inside Nicosia FIR.
The problem is Turkey's air traffic controllers have severed all communications with their Greek Cypriot counterparts, whom they don't recognize. Instead, they instruct pilots flying through Turkish airspace to contact Ercan Air Control Center when crossing into Nicosia FIR.
Many pilots do so, allowing Ercan ACC to fill an air communications gap between Ankara and Nicosia air traffic controllers, said Turkish Cypriot Civil Aviation chief Hasan Topaloglu.
The Turkish Cypriots say that the problem would be solved overnight if Nicosia established even indirect communication with Ercan _ a move that Turkey endorses. But the Greek Cypriots view such calls as a Turkish ploy to gain legitimacy for the breakaway state.
"It is very clear from statements of Turkish officials that indeed Turkey is actively pursuing international recognition," said Kozakou-Marcoullis.