Report: Pilot mistook planet for plane TORONTO, April 17 (UPI) -- A sleepy Air Canada pilot mistook a planet for another aircraft when he dropped his plane nearly 400 feet to avoid an imaginary collision, a report found. The Transportation Safety Board of Canada report released Monday said the tired Air Canada first officer on the Toronto-to-Zurich flight in January 2011 at first mistook the planet Venus for another aircraft, then plunged his Boeing 767 394 feet to avoid an imagined crash with an oncoming U.S. C-17 military cargo plane, the Toronto Star reported. Ninety-five passengers were on board. The investigation raised questions about standards for pilots on overnight flights to Europe because of the "inherent risk of fatigue" caused by disrupted sleep patterns. The report determined pilot fatigue and broken rules concerning napping in mid-flight were among the causes of the incident in which 16 people were injured. The first officer in question opted to take a nap instead of having a cup of coffee, the report said. The first officer had just awakened when the flight captain said a U.S. cargo plane was flying toward the Air Canada plane. The officer "initially mistook the planet Venus for an aircraft," then thought an oncoming U.S. plane was descending from above, threatening an "imminent collision," the report said. In reality, the U.S cargo plane was flying about 984 feet below the Air Canada plane. "Under the effects of significant sleep inertia [when awareness and performance are degraded after sleep], the first officer perceived the oncoming aircraft as being on a collision course and began a descent to avoid it," says the report. Canadian Aviation Regulations permit pilots to take mid-flight naps of no longer than 40 minutes, the Star said. However, the report said the first officer slept for 75 minutes, which "likely placed [him] into slow-wave sleep and induced longer and more severe sleep inertia." Barry Wiszniowski, chairman of Air Canada Pilots Association's flight safety division, said fatigue has been a risk on some Air Canada routes for "a number of years."