A sleepy passenger jet pilot sent his aircraft hurtling towards the ground in an effort to avoid a collision - with Venus, 25 million miles away from the Earth.
An official report by the Transportation Safety Board of Canada, which has just been released, said that 14 passengers and crew on board the Air Canada flight were injured in the ordeal when the first officer, when had just woken up, made the error.
"Under the effects of significant sleep inertia [where a person can be tired immediately after waking up], the first officer perceived the oncoming aircraft as being on a collision course and began a descent to avoid it."
The problems began aboard a Boeing 767 passenger flight flying from Toronto to Zurich with eight crew members and 95 passengers.
"The FO [first officer] initially mistook the planet Venus for an aircraft but the captain advised again that the target was at the 12 o'clock position [straight ahead] and 1,000 feet below," it said.
"When the FO saw the oncoming aircraft, the FO interpreted its position as being above and descending towards them. The FO reacted to the perceived imminent collision by pushing forward on the control column."
Louisa Pickering, a passenger on the flight told the BBC she was asleep when the plane hurtled toward the earth and she hit the ceiling.
"I hit the top of the ceiling and fell back to the ground," she said. "After that it was kind of chaos."
The plane nosedived for 400ft before the captain straightened it out.
None of the passengers or crew was wearing seatbelts and seven people required treatment at a hospital.
Air Canada said its regulations did not require further changes. Restrictions on hours worked at any one time were last cut in 1996 - from 15 hours to 14.
"The regulations are not sensitive at all to the time of day. [North Atlantic flights] are certainly fatiguing in comparison to most other flying," said Air Canada Pilots' Association president Paul Strachan.
"The regulator will have done a risk assessment and obviously is satisfied that the risk was acceptable," he added.
Jon Lee, the chief investigator, said the incident highlighted the dangers of fatigue and lethargy in airline crews.
He said: "This occurrence underscores the challenge of managing fatigue on the flight deck."