Flying over parts of Cyprus is made more dangerous by the fact that rival air traffic control centers on the ethnically split island are giving instructions to planes, creating "confusion and misunderstanding" among pilots, a report by Europe's air safety agency says.
The internal 2015 report compiled by the European Aviation Safety Agency and seen by The Associated Press says a statistical analysis shows that overall, the risks are acceptable as the probability of a "catastrophic" accident occurring is very small. For example, the report states that the mean expected accident frequency between two aircraft over Cyprus is about one in a billion.
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But the agency said the situation inside a sizeable part of the Nicosia Flight Information Region — a 175,000 square kilometer (67,567 sq. mile) swathe of airspace over and around Cyprus — is getting to the point where risks to safety can no longer be considered acceptable.
"The assessment concludes that close monitoring of the situation is needed as it is at the limit of acceptability," the report says. "The agency recognizes that this situation is far from optimal."
That's because flight instructions from two different air control centers can degrade established safety margins, such as the minimum distance two aircraft can be from each other.
Only air traffic controllers in the internationally-recognized, southern part of Cyprus are permitted to issue flight instructions to aircraft passing through Nicosia FIR. Yet controllers at the unrecognized Ercan airport in the island's breakaway Turkish Cypriot north also give instructions to aircraft flying through the northern third of Nicosia FIR that they consider their own, sometimes confusing pilots.
According to the report, which cites Cyprus statistics, there were six instances in 2014 where aircraft came closer to each other than the minimum allowed distance. That followed seven such instances in 2013 and another four the year before that.
More disturbingly, there were two reported incidents in 2014 where onboard systems designed to automatically avoid a mid-air collision had been activated — meaning that planes were close enough to possibly collide within around a minute.
A total of 18 such instances occurred within Cyprus airspace between 2011 and 2015, according to the database of the International Air Transport Association.
Separately, the report also raised safety concerns because Turkey does not notify Cypriot authorities of warplane flights as it doesn't recognize the island as a state. It says that, while very remote, the probability of an accident between a civilian aircraft and a military jet is statistically higher as a result.
From 2011 to 2014, annual air traffic through Nicosia FIR averaged between 150,000 and 180,000 flights.
The situation today remains unchanged, said Christos Petrou, executive director of the Mediterranean Flight Safety Foundation. "This problem is not something you can ignore," he said.
Steps are being taken to mitigate the risk. Air traffic controllers in the south operate in a "state of 'permanent contingency', constantly monitoring communications between Ercan and passing aircraft to prevent any accident or serious incident from happening.
The problem stems from the island's division in 1974 when Turkey invaded following a coup mounted by supporters of union with Greece.
Breakaway Turkish Cypriots established their own air traffic control center in 1977, six years before declaring independence, which was recognized only by Turkey.
But neither Turkish, nor Turkish Cypriot controllers communicate with their Greek Cypriot counterparts in the island's south. That creates problems when Turkish controllers don't tell pilots flying into Nicosia FIR to check in with counterparts in the island's south, telling them instead to speak with controllers at Ercan airport.
"As a direct consequence, the most basic safety procedures are not being respected for a long time within the northern part of the Nicosia FIR," says the report.
"This operational environment has created and still creates confusion and misunderstanding by the users of the airspace in question."
To ensure safety, international aviation bodies have published bulletins and briefings aimed at bringing pilots up to speed about the situation and to use safe procedures.
The AP highlighted the problem in an Aug. 5, 2011 report that included descriptions of several instances of "near-misses" where aircraft got dangerously close to each other.
In the report, the EASA recommends that the European Union and the UN's top aviation body — the International Civil Aviation Organization — get Cyprus and Turkey to "work together" to resolve the issue.
The agency recommends that coordination between Cyprus and Turkey on advisories regarding military flights and "danger areas" inside Nicosia FIR be facilitated "through operation of a unit in a third country."
If that can't happen, it recommends that either ICAO or European authorities step in to ease coordination.