During cruise ship season, the skies over Ketchikan buzz with float planes taking cruise ship passengers on flightseeing tours.
It’s a busy area with fickle weather, enough so that airlines have installed expensive equipment in their planes to help avert mid-air collisions. And after Monday’s crash that killed six people, one big question for investigators is why equipment to avert a disaster failed.
Mid-air collisions occur regularly in Alaska. A crash last summer outside Anchorage killed a pilot, while another in 2016 near a Yukon River village left five people dead.
Commercial flightseeing operators like Taquan Air and Mountain Air Service – the ones involved in Monday’s crash – aren’t required to use transponders that broadcast their planes’ locations.
But here’s the thing that makes Monday’s crash perplexing: According to the Federal Aviation Administration, both planes – a de Havilland DHC-2 Beaver with a pilot and four passengers, and a de Havilland DHC-3 Otter with a pilot and 10 passengers – were equipped with transponders.
Specifically, they were using a system called ADS-B, FAA spokesman Allen Kenitzer said in an email.
ADS-B is a relatively new GPS-based technology pioneered in Alaska. In theory, the system can warn pilots about other planes in time to avert a collision, said Scott Van Valin, who runs an air service called Island Air Express that flies in and out of Ketchikan.
“The pilots hear it through the headsets of the plane: ‘Traffic. Traffic. Traffic,’” he said. The system, he added, gives pilots time to communicate and decide how to avoid each other.
But many details about Monday’s crash, and how the navigation systems may or may not have worked, remain unknown.
One big question is whether the planes had the ability not just to broadcast ADS-B signals, but also to receive them and detect other aircraft. Some systems are only set up to send signals out.
The company that was running the Otter, Taquan Air, said in an email that its plane was equipped to receive ADS-B signals. FAA and NTSB officials would not say if that was the case for Mountain Air Service’s Beaver – or if that plane was only broadcasting its signal out, which may not have allowed its pilot to detect the Otter.
Why aren’t all planes required to have that equipment? Buying and installing a system to receive ADS-B signals can cost $8,000 — as much as half of what an inexpensive small plane is worth.
In the past, investigators have blamed Ketchikan-area crashes on marginal weather, and in one case, on the schedule pressure and safety culture of a tour company. But with weather reported to be partly sunny with 10 miles of visibility, Monday’s crash appeared to be different.
At a news conference Tuesday, NTSB member Jennifer Homendy said the two planes were both flying back to Ketchikan, in a similar direction. The Otter was descending, the Beaver was holding steady, and the planes converged, she said.
At another news conference Wednesday, Homendy said the NTSB would look into how the planes’ transponders were functioning. She also said the board may do a “visibility study,” which she described as “looking at the field of vision in both cockpits to see what both pilots could see.”
“Looking at the structures: Was there anything that may have blocked their view in any way?” she said.
The airspace over Ketchikan gets busy in the summer: There are as many as 14 different commercial flight operators in the area, according to a voluntary agreement between them signed in 2017.
Those companies, in the agreement, set out additional, cooperative safety measures that they’ve incorporated into their operations. They include specific radio channels to use and spots for planes to announce their locations, along with route and altitude guidelines for different areas.
Experts also stressed that pilots shouldn’t be dependent on their technology. There’s a safety mantra in the industry called “see-and-avoid”; federal rules require pilots to vigilantly watch for other planes.
Even so, pilots don’t always have much time to avert a mid-air collision.
Last summer, Bruce Markwood survived one outside of Anchorage that killed the pilot of the other plane, who was a flight instructor. At a seminar earlier this year, he described looking down from the cockpit at the shadow of his plane, seeing another shadow and realizing: “‘Oh, wow, there’s another plane here.’”
“I looked up at that point, and his spinner was basically in my windshield,” he said. “I’m here by the grace of God. I pulled back as hard as I could on my yoke, and made contact.”
The collision sliced off one of Markwood’s wheels. He was unharmed after an emergency landing at Lake Hood in Anchorage, on a single wheel.