Aviation authorities have reported two near-misses between drones and passenger planes at Heathrow and Manchester airports. The UK Airprox Board said that one drone was a "wingspan away" from an airplane landing at the Heathrow airport.

Amongst the latest six such incidents, one drone was going to collide with a small light aircraft and two other incidents involved near-misses with two bigger passenger planes. According to a pilot at the Heathrow airport, a drone helicopter passed less than 30 metres from his A319 in the middle of his flight path.

Since the pilot was unable to take any action, police investigated the incident, however the drone's operator could not be traced. Similarly in Manchester, a red and white drone was seen nearly less than 15 metres away from a passenger plane. Investigators said: "Separation had been reduced to the bare minimum and chance had played a major part in events."

Calls are being made to urge drone users to be registered. "Once again we see these near misses happening at altitudes where manned aircraft frequently operate and also on approach to airports where there is absolutely no reason for a drone to be. We need to catch the people that are doing this before we see a collision and loss of life," said a Balpa spokesperson, reported The Guardian.

Earlier, a government counter-terrorism expert warned that passenger planes are running a constant risk of being downed by drones being flown too close to them. "This is happening on a weekly basis," Home Office counter-terrorism expert Colin Smith said. "We are not just talking about hundreds of feet, we are talking thousands. People are flying drones in the path of aircraft, having a look, seeing if they can get alongside the cockpit to see what is going on."

According to the Civil Aviation Authority (CAA): "Drone users have to understand that when taking to the skies they are entering one of the busiest areas of airspace in the world — a complex system that brings together passenger aeroplanes, military jets, helicopters, gliders, light aircraft and now drones...The rules for flying drones are designed to keep all air users safe. Anyone flouting these rules can be charged and prosecuted and any drone user found guilty of endangering an aircraft could face imprisonment."