SAN FRANCISCO — Eleven seconds from disaster.
That’s how close a Mountain View pilot calculated an Air Canada Airbus 320 was to striking the first of four fully-loaded jet liners on a SFO taxiway Friday in one of the scariest close-calls aviation experts have ever seen.
“If you just sit there and count to 11 seconds, we’re not talking about a lot,” said Max Trescott, a general aviation pilot for more than 40 years and instructor at Palo Alto Airport. “That’s ridiculously close.”
FlightAware, which monitors air traffic online, determined Air Canada flight 759 dropped to as low as about 175 feet on approach at SFO as the wayward pilot mistakenly headed for Taxiway C, instead of Runway 28R. Based on those figures, the plane’s speed at the time and the positioning of the four planes awaiting departure on the taxiway, Trescott did some math.
“On a normal 3-degree glide slope, an aircraft descends 320 feet for every nautical mile flown,” Trescott explained in his blog Trends Aloft. “So at 175 feet, an aircraft would be 0.55 nautical miles from the touchdown zone. The typical landing speed for an A320 is around 130 knots to 140 knots. At 140 knots, an aircraft covers 2.33 miles per minute, so it could travel 0.55 nautical miles in a little over 14 seconds. Of course, if you figure a typical airliner is perhaps 40 feet high … then it would have been about 11 seconds to impact.”
The incident has set the international flying community abuzz and rightfully so, Trescott said.
“I would say this is quite alarming and uncommon to be this close,” he said. “That’s relatively rare.”
Another aviation expert said this could have triggered the greatest aviation disaster in history with almost 1,000 passengers on all five airplanes involved, along with four aircraft filled with fuel.
“We may have investigators in the Bay Area within the next few days,” said NTSB spokesman Keith Holloway. “It is possible that part of the NTSB investigation going forward will be to review (air traffic control) procedures and practices for that airport.”