Investigators comb plane wreckage after four dead in mid-air collision north of Whistler

The mountain ridges and thermal currents of Pemberton, B.C., appeal to gliders who catch currents and ride them, bird-like, through the sky.

The airspace immediately over the community is a "see and be seen" area without radar or aircraft control guidance, suggesting that the explanation for a tragic collision that occurred on a sunny cloudless day – killing four people and sending debris raining down over a nearby campground – could be that the pilots simply didn't see each other.

As they tried to piece together the cause of the collision, which took place Saturday just south of Pemberton, Transportation Safety Board investigators started with the "preliminary assumption" that the two pilots failed to spot each other in time to change course. "Your eyes can't see everywhere at the same time," Bill Yearwood, TSB's regional manager for aviation in the Pacific, said Sunday. "We know from our investigations that humans are not well-designed for that. We do miss things that are on a collision course."

Pieces of the aircraft were still behind yellow tape on Sunday at the Nairn Falls campground as investigators studied the scene.

In the campground, a few minutes south of Pemberton and close to where the mid-air collision occurred, Melanie Mathews recounted how, as she stepped out of her tent on Saturday, chunks of metal began falling from the sky. "It was just like a sea of debris coming down, it didn't seem real," Ms. Mathews said on Sunday, pointing to the tree tops towering over her campsite.

Among the dead are Terry Gale, the pilot of the Cessna, and his wife Rita Gale. Rudy Rozypalek, a pilot, was aboard the glider; the other passenger's identity is not known. By Sunday night, the RCMP had not yet publicly identified the deceased, but next of kin had been notified and confirmed the three names to The Globe and Mail.

Mr. Gale, a 42-year-old father who served in the Canadian Armed Forces with Princess Patricia's Canadian Light Infantry and did one overseas tour in Bosnia, retired as a master corporal in the late 1990s. He settled in the B.C. Interior where he had grown up, and, in addition to working in a local mill, served as a master corporal with the Canadian Rangers, the group of part-time soldiers who keep watch on some of Canada's most remote areas for the military.

Tom Nickel, who has known Mr. Gale since they met as 12-year-old cadets, said his friend started flying lessons in 2008 and obtained his pilot's licence about a year ago. Mr. Nickel said that Mr. Gale had performed the flight to Vancouver Island about four times and this time was planning to visit his wife's sister. "He was the hardest-working person I've ever known. He just never stopped. He was like the Energizer Bunny: go, go, go, go, always doing something," Mr. Nickel said.

Mr. Rozypalek ran the Pemberton Soaring Centre and was well-known in the gliding community as an instructor and advocate for the sport. The soaring centre was closed Sunday. In a statement, sister-in-law Sheila McCutcheon said Mr. Rozypalek was an immigrant from Czechoslovakia and built a business that is in its 20th year of operation. "Rudy was loved and respected by our family and in this community," the statement said. "We are devastated for our own loss and also deeply saddened for all the other people's losses who were also involved."

The TSB said it will consider "all practical safety improvements" relating to the collision, including whether smaller, low-flying aircraft should be equipped with some sort of anti-collision system to protect against human error.

In the past 10 years, the TSB has closed three investigations relating to mid-air collisions, two of which happened in B.C. airspace, according to its website. No recommendations resulted from the latest investigations in the Pacific region, Mr. Yearwood said.

A portable GPS retrieved from one of the aircraft should provide investigators with clues, as will the scars and scratches on the aircraft and witness testimony. Investigators know from the Cessna's flight plan that the couple was travelling from 100 Mile House to Nanaimo, B.C., and had either already refueled in Lillooet or was planning to refuel there. The glider, which Mr. Yearwood said took off using an engine but then used air currents to sustain itself, was not required to file a flight plan.

The Pemberton airport was not experiencing heightened congestion at the time of the crash, Mr. Yearwood said.

With a report from Greg McArthur