The aircraft engaged in the accident was produced in 1954, serial number 12903, registration G-ANBB, and had a total of 18444 airframe hours with 5380 cycles.

The ATC supplied the crew with meteorological and other necessary information: "Wind is calm, visibility 5 kilometres, shallow fog over the runway is forming now, clouds 2/8 stratocumulus 1800 metres, QNH 1011, QFE 968 millibars (mb).

After Dolsko make left pattern holding, descend down to 4500 by QNH, report inbound."

When the pilot asked ATC if the Instrument Landing System (ILS) was operating, the ATC answered he had a radar contact with the aircraft when positioned 20 NM southeast from the airport and advised the crew to make an ILS approach to RWY 31, and to report after descending to 4500 ft by QNH pressure.

The crew acknowledged, reported they were at 4500 ft and would call over Dolsko VOR inbound for the outer marker and asked again if the ILS was in service.

ATC then gave the position "abeam Dol" and after it was acknowledged by the crew, he asked if they had visual contact with the runway.

The ATC issued clearance for landing and advised that the approach and runway lights were set to maximum intensity.

Mengeš Non-Directional Beacon (MG NDB) is at 4,2 NM from the RWY 31 threshold and was already passed).

2) Official report stated the probable cause of the accident to be the pilot-in-command missing to set his altimeter to the QFE 968 mb in accordance with the information passed by the ATC.

If the crew was relying on visual cues, which seems highly probable, they could have misjudged the angle of their approach.

Combined with the false altitude readings and dark forest below, the illusion would have given the impression of being higher than they were.