German investigators have detailed a serious airprox incident involving an Airbus A320 which encountered a light aircraft at about 2,800ft while descending towards Dusseldorf.

Investigation authority BFU says the light aircraft – an Asso Aerei V, operating Freiburg-Lauenbruck under visual rules – had flown into controlled airspace without permission and without making radio contact.

The pilot stated that he had navigated using maps after a fuse problem affected the radio and navigation system, and only realised the error when he saw the A320.

While BFU does not identify the Russian operator involved, it says the A320 was Bermuda-registered and had been flying from Moscow Sheremetyevo. The flight details match those of an Aeroflot service.

The encounter, on 24 September last year, occurred in Class D airspace.

Although the A320 crew had been warned of another aircraft at 2,400ft, the crew could not make visual contact. The air traffic control short-term conflict alert sounded and a resolution advisory, ordering a climb, was issued by the A320's collision-avoidance system.

At one point the light aircraft was 100ft vertically from the A320 at a horizontal distance of just 0.8nm. BFU says the A320, carrying 156 passengers and six crew members, passed the aircraft with a separation of 0.07nm and 600ft.

BFU says the A320 subsequently landed at Dusseldorf and the Asso continued to Lauenbruck.

Source: Cirium Dashboard