It was only when shocked passengers alerted flight attendants to the fighter jets that surrounded the plane, that the pilots were roused as the crew banged on the cockpit door. They then contacted Greek authorities. By then, it had been nearly an hour without any contact.
A Delta Airlines spokesman told the Daily Star: "While transiting to Greek airspace, the flight crew of Delta flight 8957, a charter operation from Hahn, Germany to Kuwait, was unable to establish radio communications with Greek air traffic control for a short period.
"This occurred during a hand-off between air traffic control agencies and communications were expeditiously re-established. At no point did the Boeing 767-400ER leave its planned route of flight."
news.com.au has contacted Delta for further comment.
THIS IS YOUR CAPTAIN SLEEPING
The Australian Transport Safety Bureau (ATSB) has identified 12 accidents and 64 near misses over the last 10 years in which fatigue was considered relevant. There were two deaths as a result of these accidents.
The Civil Aviation Safety Authority is rolling our new rules around pilot fatigue which factor in the impact of flying through multiple time zones. Airlines have until 2017 to develop new systems.
Meanwhile, a 2013 survey of UK airline pilots found that more than half have fallen asleep in the cockpit and a third have woken up to find their co-pilot asleep.