But the plot was foiled after the prisoner was shot and the chopper forced to land in the prison's parking lot.
The dramatic escape attempt was one of a handful involving helicopters in Greece, and the first time such plans have failed.
Authorities said the chartered helicopter—carrying two armed passengers, a pilot and a technician—first tried to rip off the chicken-wire fence surrounding Trikala prison with a hook dangling from a rope. But that didn't work, so a rope was lowered down to whisk away Panagiotis Vlastos. Another prisoner, an unnamed Albanian national also in the courtyard at the time, may also have been part of the escape plan.
At the same time, the armed passengers used AK-47 assault rifles to fire on the prison guards. One guard, who was inside a post, was slightly injured by shards of flying glass. He and others returned fire, injuring Vlastos, who had managed to climb into the helicopter, as well as the helicopter's technician. Vlastos fell from a height of about 3 meters (10 feet) into the courtyard, and the helicopter was eventually grounded in the parking lot.
Vlastos, 43, is a convicted murderer and racketeer serving a life term who had tried and failed three times before to escape from prison.
Prison officials told TV stations Mega and NET that they recovered well over 500 bullets fired from the helicopter. The Ministry of Justice, in statements describing the escape attempt, added that the helicopter passengers also carried, but did not use, "improvised explosive devices."
Authorities said Vlastos was wounded in the legs but is being treated in the prison hospital because his injuries were not deemed serious enough for a transfer elsewhere. The technician's hand was slightly wounded.
It was not immediately clear if the pilot and flight technician had willingly participated in the escape attempt or had been forced to fly to the prison, which is located 328 km (205 miles) northwest of Athens. Also unclear was whether the second would-be escapee was in on the scheme or just happened to be in the courtyard and tried to take advantage of the situation.
The helicopter was hired from a western Athens suburb and was supposed to fly to Thessaloniki, in northern Greece. But it deviated from is flight path to head to the prison.
This is the third time a helicopter has been used in an attempted prison escape in Greece. Convicted criminals Vassilis Paleokostas and Alket Rizaj were whisked by helicopter from the high-security Korydallos prison in Athens in June 2006. They were caught, but escaped for a second time—again using a helicopter—in February 2009. Paleokostas is still at large.
Vlastos was first arrested in 1994 in the murder of two members of a rival criminal gang. He was convicted last year as the behind-the-bars mastermind of the kidnapping of shipping tycoon Pericles Panagopoulos. Panagopoulos was kidnapped in January 2009 and released after eight days, when a ransom of (EURO)30 million was paid.
While awaiting trial for the kidnapping, Vlastos tried to escape in December 2011 from Korydallos prison along with three members of armed anarchist group Conspiracy Nuclei of Fire. The four used a pistol and knives to take hostage three prison guards and 25 visiting relatives of other prisoners. The four surrendered to authorities after a five-hour standoff.
Vlastos had also tried to escape, unsuccessfully, in 1994 and 1998.
Demetris Nellas contributed to this report from Athens.