Preliminary TSB report: (paraphrased)
Flight 183 was on decent into Kelowna from Toronto when the pilot lined up on the 3300' by 75' runway at Vernon Regional Airport instead. The plane was configured for landing and about 30 to 40 seconds from touchdown before the pilot called a go-around. The ILS/DME approach at Kelowna wasn't authorized and VFR conditions prevailed, despite a large forest fire burning to the south and east of the city. As the plane neared its destination, the crew was told by air traffic control that the NDB approach was also unavailable. However, neither the dispatcher nor the crew was told the reason the navaids were unauthorized. They were working perfectly, but the published missed approach for both infringed on the restricted airspace around the fire. As the plane descended from the north, its navigation gear picked up the signals from the ILS systems and gave the first officer, the non- flying pilot, a constant readout of the distance from Kelowna. So, when the pilot mistook the Vernon strip for Kelowna, he turned the plane 90 degrees to the right of the Kelowna runway heading and started a 1800-feet-per-minute descent to the wrong airport. The plane's navigation equipment was clearly showing the flight to be 30 miles from the right airport. However, the first officer had been distracted by a radio call from terminal staff in Kelowna concerning the flight's gate assignment and it wasn't until the plane was well-established on final for RW23 at Vernon that the first officer noticed the discrepancies on the panel and suggested a go-around. Just as they were tucking the gear up, the TCAS warned of conflicting traffic in the pattern at Vernon. A small Cessna saw the A319 approaching and made an evasive maneuver.