Thick fog blinded air traffic controllers causing a taxiing plane to hit a parked aircraft at East Midlands Airport, a report has found.
The wing tip of a Ryanair plane scraped a Jet2 aircraft as it moved to park early on 30 April.
The Air Accidents Investigation Branch (AAIB) said low visibility procedures were in place but controllers could not see that a space was already occupied.
Neither plane was carrying passengers at the time and no crew were hurt.
The AAIB said the Ryanair plane, a Boeing 737 with two crew on board, was taxiing towards the airport's main parking area, having arrived from Stansted Airport, when it struck the Jet2 aircraft, also a Boeing 737.
'Seduced the crew'
"Due to the poor weather and their elevated position in the control tower, air traffic controllers could not see the aircraft, taxiway or apron," the report said.
The fog had made stand 22, where the Jet2 plane was parked, "invisible" to the controllers and the Ryanair plane was given an "unachievable taxi clearance".
In addition, the report said the airport's Surface Movement Radar - meant to be "the eyes" of air traffic controllers when visibility is poor - was not designed to show stationary vehicles.
The report concluded: "The fallibility of the human eye in accurately judging relative distance at range seduced the crew into thinking that safe separation had been achieved."
East Midlands Airport (EMA) closed stand 22 while it carried out a safety review following the crash.
An EMA spokesman said: "Immediately following [the collision] an internal team was assigned to review relevant procedures and changes have been made to our operating procedures that control the movement and parking of aircraft on the apron.
"Going forward, the airport is looking at how new technology could further improve procedures. "