US aviation authorities are investigating a near miss at a San Francisco airport after an Air Canada plane almost landed on a crowded taxiway rather than the runway. 
 
 The Air Canada Airbus 320 was cleared to land at a runway at San Francisco international airport late on Friday. The pilot, however, inadvertently began descending toward one of the taxiways, where four airplanes laden with passengers and fuel sat waiting for permission to take off, according to the US Federal Aviation Administration. 
 
 Audio of the conversations between air traffic control and pilots, posted on the Live ATC website, captured the confusion. The Air Canada pilot can be heard asking if he’s clear to land, given that he can see other lights on the runway. He’s told there are no other planes on the runway. 
 
 Another voice chimes in, sounding the alarm over Air Canada’s trajectory: “Where’s this guy going? He’s on the taxiway.” 
 
 The pilot was immediately instructed to pull up, circle around and approach the landing again. “It looks like you were lined up for Charlie [Taxiway C] there,” the air traffic controller told the pilot. The taxiway sits parallel to the runway. 
 
 A United Airlines pilot then weighed in: “United One, Air Canada just flew directly over us.” The air controller responded: “Yeah, I saw that, guys.” 
 
 About 15 minutes later, the Air Canada flight landed safely. “The plane made another approach and landed without incident,” the Federal Aviation Administration said in a statement. 
 
 The FAA, which described the incident as “very rare”, is now investigating how close the Air Canada plane came to the four other jets sitting on the taxiway at the time. 
 
 The San Jose Mercury News, which was among the first to report the story, said the near miss was being widely discussed among aviation circles. 
 
 “If it is true, what happened probably came close to the greatest aviation disaster in history,” retired United Airlines captain Ross Aimer told the newspaper. “If you could imagine an Airbus colliding with four passenger aircraft wide bodies, full of fuel and passengers, then you can imagine how horrific this could have been.” 
 
 Air Canada also said it was investigating the reports. Five crew and 135 passengers were onboard the flight from Toronto when the aircraft was directed to make another approach, a spokesperson said in an email. “The aircraft landed normally without incident. We are still investigating the circumstances and therefore have no additional information to offer.” ||||| An Air Canada plane narrowly averted disaster after it almost landed on a taxiway with four other planes on it in San Francisco Friday night. 
 
 Air Canada flight AC759 from Toronto was cleared to land on runway 28R just before midnight, a statement from the Federal Aviation Administration said. 
 
 "However, the pilot inadvertently lined up for Taxiway C, which runs parallel to the runway," the statement said. "An air traffic controller sent the Air Canada jet around." 
 
 In an audio recording of the conversations between air traffic control and pilots available from Live ATC, the Air Canada pilot tells air traffic control he sees other lights on the runway before being told there are no other planes on 28R. 
 
 John Cox spent years as an aviator and crash investigator 3:30 
 
 "You can begin to see there is uncertainty in the Air Canada crew's mind about what's going on," said former commercial pilot and aviation investigator John Cox, referencing the recording of communications. 
 
 Cox added that proven technologies have long been in place to prevent runway collisions. 
 
 "There are electronic devices that send radio signals up to the airplane for vertical and lateral alignment. And why those were not being followed is going to be a central question the investigators will look at," he said. 
 
 In the recording, a United Airlines pilot is heard saying "United One, Air Canada just flew directly over us." 
 
 Another voice is heard saying, "Where's this guy going? He's on the taxiway." 
 
 When air traffic control realizes the plane is headed for the taxiway, it is directed to go around and approach again. It landed without incident on the second attempt. 
 
 In an interview with the San Jose Mercury News, a former pilot said the plane avoided what could have been a "horrific" collision. 
 
 "If it is true, what happened probably came close to the greatest aviation disaster in history," said retired United Airlines Capt. Ross Aimer, CEO of Aero Consulting Experts. 
 
 "If you could imagine an Airbus colliding with four passenger aircraft wide bodies, full of fuel and passengers, then you can imagine how horrific this could have been," he said. 
 
 SF airport requires 'precision flying' 
 
 The FAA is investigating how close the Air Canada plane came to the four planes on the taxiway, adding that this type of incident is "very rare." 
 
 Cox echoed that near-hits during takeoffs and landings are rare, but was quick to identify certain design elements of the San Francisco airport that may have exacerbated the troubled approach. 
 
 He flew into the same airport "many, many times" as a pilot and said it requires "precision flying." 
 
 For example, the two adjacent runways are the closest of any pair used by commercial aircraft in the world, only about 229 metres between them. 
 
 Similarly, fewer than 150 metres separates the runway 28R from the taxiway. 
 
 But Cox still questions how the Air Canada crew may have confused the two strips of tarmac. At the San Francisco airport, runways are illuminated by clear or amber-hued lights while the taxiway is lined with blue lights. 
 
 "Everybody here did a good job" in averting a potential catastrophe, Cox said. "Now we just need to know why the Air Canada crew thought the taxiway was the runway to land on. 
 
 In a statement, an Air Canada spokesperson said the airline is also investigating. 
 
 "Air Canada flight AC759 from Toronto was preparing to land at San Francisco airport Friday night when the aircraft initiated a go-around," Peter Fitzpatrick said in the emailed statement. 
 
 "The aircraft landed normally without incident. We are still investigating the circumstances and therefore have no additional information to offer." ||||| SAN FRANCISCO — In what one aviation expert called a near-miss of what could have been the largest aviation disaster ever, an Air Canada pilot on Friday narrowly avoided a tragic mistake: landing on the San Francisco International Airport taxiway instead of the runway. 
 
 Related Articles New revelations in SFO near-miss: Air Canada flight got as low as 175 feet Sitting on Taxiway C shortly before midnight were four airplanes full of passengers and fuel awaiting permission to take off, according to the Federal Aviation Administration, which is investigating the “rare” incident. An air traffic controller sent the descending Air Canada Airbus 320 on a “go-around” — an unusual event where pilots must pull up and circle around to try again — before the safe landing, according to the federal agency. 
 
 FAA investigators are still trying to determine how close the Air Canada aircraft came to landing and potentially crashing into the four aircraft below, but the apparent pilot error already has the aviation industry buzzing. 
 
 Courtesy of flightaware.com 
 
 “If it is true, what happened probably came close to the greatest aviation disaster in history,” said retired United Airlines Capt. Ross Aimer, CEO of Aero Consulting Experts. He said he’s been contacted by pilots from across the country about the incident. 
 
 “If you could imagine an Airbus colliding with four passenger aircraft wide bodies, full of fuel and passengers, then you can imagine how horrific this could have been,” he said. 
 
 Peter Fitzpatrick, an Air Canada spokesman, said Flight AC759 from Toronto “landed normally without incident” after the go-around. 
 
 Reading this on your phone? Stay up to date with our free mobile app. Get it from the Apple app store or the Google Play store. 
 
 “We are still investigating the circumstances and therefore have no additional information to offer,” he said. 
 
 The SFO spokesman referred inquiries to the FAA, saying the airport had no comment on the event. 
 
 The aircraft had been cleared to land on Runway 28R, which runs parallel to that taxiway, according to the FAA. The pilot, flying the plane manually on a clear night, lined up wrong, the federal agency said. 
 
 Audio from the air traffic controller communication — archived by a user on LiveATC.net and reviewed by this news organization — recorded the confused Air Canada pilot asking if he’s clear to land on 28R because he sees airplane lights on the runway. 
 
 “There’s no one on 28R but you,” the air controller responds. 
 
 An unidentified voice, presumably another pilot, then chimes in: “Where’s this guy going? He’s on the taxiway.” 
 
 The air controller quickly tells the Air Canada pilot to go around, and adds, “It looks like you were lined up for Charlie (Taxiway C) there.” 
 
 A United Airlines pilot radios in: “United One, Air Canada flew directly over us.” 
 
 “Yeah, I saw that, guys,” the control tower responds. 
 
 The event has launched a discussion among airline circles, Aimer said. 
 
 “This is pretty huge. My buddies called and asked if I knew about it,” the former pilot said. “They’re a sitting duck on the taxiway. They can’t go anywhere.” 
 
 Like our Facebook page for more conversation and news coverage from the Bay Area and beyond. 
 
 ||||| Disaster averted at SFO after jet lines up to land on taxiway rather than runway 
 
 A potential disaster was averted at San Francisco International Airport after the pilot of a commercial jet carrying 140 people mistakenly lined up to land on a bustling airplane taxiway rather than the parallel runway, officials said Tuesday. 
 
 The Air Canada jet, an Airbus A320, was instructed by an air traffic controller to halt its descent and conduct a “go-around” just before midnight Friday as it approached the taxiway, where four commercial planes full of passengers and fuel were preparing to take off, said the Federal Aviation Administration. 
 
 The plane, which was inbound from Toronto, carrying 135 passengers and five crew members, safely circled and landed on Runway 28R, the agency said. Officials said the FAA is investigating the incident, including “the distance between the Air Canada aircraft and the jets that were lined up on Taxiway C.” 
 
 Departing and parked aircraft intersect at San Francisco International Airport, Tuesday, July 11, 2017, in San Francisco. An Air Canada Airbus A320 was cleared to land on one of the runways at the San Francisco airport just before midnight on Friday, July 7, when the pilot "inadvertently" lined up with the taxiway, which runs parallel to the runway. There were other aircraft lined up on the taxiway waiting for departure when the incident occurred. less Departing and parked aircraft intersect at San Francisco International Airport, Tuesday, July 11, 2017, in San Francisco. An Air Canada Airbus A320 was cleared to land on one of the runways at the San Francisco ... more Photo: Marcio Jose Sanchez, Associated Press Photo: Marcio Jose Sanchez, Associated Press Image 1 of / 15 Caption Close Disaster averted at SFO after jet lines up to land on taxiway rather than runway 1 / 15 Back to Gallery 
 
 Air Canada released a statement Tuesday saying, “We are still investigating the circumstances and therefore have no additional information to offer.” 
 
 An audio recording captured the moment when the pilot, who was not identified, attempted to make the landing. He said, “Tower, Air Canada 759. I can see lights on the runway there. Can you confirm we’re clear to land?” 
 
 An air traffic controller responded, “Air Canada 759, confirmed cleared to land on 28 Right, there is no one on 28 Right but you.” 
 
 “OK, Air Canada 759,” the pilot confirmed. 
 
 A voice then interjected, “Where is this guy going? He’s on the taxiway.” At that point, the control tower instructed the pilot to go around and make another approach. 
 
 Shortly after the pilot changed course to circle around, a United Airlines pilot radioed in to the tower and said, “United 1, Air Canada flew directly over us.” 
 
 Barry Schiff, an aviation expert and former TWA captain, said “go-arounds” are not unusual but that a pilot attempting to land on a taxiway rather than a runway was extremely rare. Runway lights are always white, are particularly clear at night and are the same around the world, he said. 
 
 Photo: John Blanchard / The Chronicle An Air Canada plane almost flew into disaster at San Francisco... 
 
 “When we hear about something like that, as pilots we do wonder how in the hell that can happen,” Schiff said. “It’s really difficult to understand how two professional pilots can look out their window and mistake a taxiway for a runway.” 
 
 The outcome could have been catastrophic if the jet had not changed course, Schiff said. 
 
 “The danger of hitting or crashing into another airplane is remarkably high,” he said. 
 
 Sarah Ravani is a San Francisco Chronicle staff writer. Email: sravani@sfchronicle.com Twitter: @SarRavani
– Aviation experts say it could easily have been one of the deadliest air disasters of all time. An Air Canada Airbus A320 was cleared to land on a runway at San Francisco International Airport just before midnight Friday, when, to the shock of air traffic controllers and other pilots, the Air Canada pilot lined up to land on the parallel taxiway, where four other planes were waiting to take off, the San Francisco Chronicle reports. "Where's this guy going? He's on the taxiway," a voice says in a control tower recording. "An air traffic controller sent the Air Canada jet around" and the pilot landed safely after another approach, the Federal Aviation Administration said in a statement, per the Guardian. The four planes waiting to take off were full of fuel and passengers, meaning the incident "probably came close to the greatest aviation disaster in history," Ross Aimer, CEO of Aero Consulting Experts, tells the San Jose Mercury News. The FAA is investigating what it says was a "very rare" incident. Aviation investigator John Cox, a former commercial pilot, tells the CBC that SFO requires "precision flying" because the runway and taxiway are exceptionally close together—but that doesn't explain how the pilot could have mistaken the blue lights of the taxiway for the clear lights of the runway. He says the investigation will likely focus on why technology designed to prevent collisions apparently failed.