A potential mid-air collision involving about 80 passengers was prevented by "just 50 feet", thanks to the timely intervention of an Air Malta pilot, it was learnt yesterday.

Flight KM613, departing from Rome, and a small aircraft flew alarmingly close to each other as both were flying over Zebbug and Attard on Saturday afternoon.

As the Boeing 737 came out of the clouds making its descent into Malta at 1.23 p.m., a small aircraft suddenly appeared out of nowhere. The Air Malta captain diverted the aircraft towards Dingli in the nick of time.

The incident was confirmed by Air Malta in a short statement issued late yesterday.

The small aircraft was not equipped with a transponder and, consequently, the Air Malta pilots could not spot the impending danger on the traffic-collision avoidance system.

Passengers on the left side of the aircraft noticed the close proximity of the small plane but most of them remained oblivious to what was going on.

A 38-year old passenger who was on board the flight was shocked as he looked out of the window.

"I had just spotted the Mosta church from the window seat and suddenly, out of nowhere, I saw a small blue plane alarmingly close.

"Our pilot's manoeuvre was excellent and it probably saved the day," said the passenger, who preferred to remain unnamed.

Because of the manoeuvre, the Air Malta aircraft had to be re-guided back on track, before landing.

Though it was not possible yesterday to establish exactly the proximity of the two aircraft, sources said the pilot was heard saying over the radio it was no further than "just 50 feet, slightly above to the left".

The incident sent shock waves across the aviation industry, especially those working in the control tower.

"Even though a small aircraft was involved, the repercussions could have been catastrophic, especially because the aircraft were on their final approach, not to mention the fact that they could have possibly came crashing down on houses," the airline industry sources said.

On board the light, Italian-registered aircraft, which had departed from Gela, Sicily, were two Italian individuals, one of whom was underage, according to the sources. The small aircraft eventually landed under the surveillance of the police and the Armed Forces of Malta.

Though tragedy was avoided, many questions remain about the Italian aircraft's unwelcome presence. Probed by the local authorities, the pilot claimed he pertained to a humanitarian NGO and was on patrol near Lampedusa for illegal immigrants. However, observers in the aviation industry wondered whether such an operation could have really taken place in bad weather and visibility, as was the case last Saturday.

The pilot had permission only to use Malta as a secondary landing air ground and claimed he had landed here because the aircraft had run out of fuel.

When contacted, Joe Sultana, director of the Civil Aviation Department, confirmed that the Italian aircraft was flying at a very low altitude and, thus, could not be seen by radar.

Asked whether the aircraft had clearance to land in Malta, Mr Sultana replied:

"As such, it didn't have clearance since it didn't communicate with the air traffic control. The pilot didn't communicate because he didn't have the correct information. The aircraft was short of fuel and it had to proceed.

"These problems can happen and it's difficult to envisage what can be done in these circumstances. You could have an aircraft with radio failure and your only choice is to carry out a visual sighting."

The DCA is carrying out a technical investigation, which will seek to clarify, among other things, whether the radar could have identified the aircraft.

Aviation experts are questioning why the Italians and the aircraft were allowed to depart from Malta as early as 6 p.m. on Saturday but Mr Sultana said permission was only given after all the necessary details were taken. This did not mean no further action could be taken and the Maltese authorities are in touch with their Italian counterparts.

The aviation industry sources said: "The aircraft did not have a flight plan and its landing was possible by virtue of authorisation given by the DCA some weeks back to use Malta as a secondary aerodrome if the necessity arose - somehow, however, the pilot was calling the tower on the old tower frequencies".