The investigation into the mid-air plane crash that killed Rep. Gary Knopp and six others in Soldotna is ongoing. But the federal board that investigates airplane safety released a set of recommendations based on that incident last month.
In particular, the National Transportation Safety Board is asking the Federal Aviation Administration to require pilots to report where they are in the airspace when they’re flying within certain radio frequency zones called CTAFs.
CTAF stands for “common traffic advisory frequencies.” They’re radio frequencies that pilots can use to communicate with each other while they’re in the air.
“It’s a guide to say, ‘OK, if you live in the boundaries of this particular area, you should be on this frequency if you have a radio to be listening for other aircraft so you can help avoid a mid-air collision,'” said Paul Minelga, a Sterling-based pilot who worked for years with the FAA.
He said in most places in Alaska, reporting on CTAFs is highly recommended, but it’s not a requirement. The NTSB wants to change that.
The safety board said in its February report that requiring reporting could be a way to prevent mid-air collisions — of which there were 14 in Alaska between 2005 and 2020, including the accident in Soldotna.
The NTSB said it was not clear what radio frequencies each plane was using at the time of that incident.
Knopp’s plane, a Piper Aztec, departed from the Soldotna airport, which uses one CTAF — 122.5.
The other plane, a de Havilland Beaver belonging to High Adventure Air Charters, took off from Longmere Lake. There’s technically no CTAF associated with the lake but the report says pilots who fly around Longmere typically monitor the same channel as the Soldotna airport.
That gray area is an example of how the boundaries between CTAF zones can be blurred. In the airspace above Soldotna, for example, there are five different and overlapping CTAFs. So it’s not necessarily a given that pilots flying near each other will be communicating on the same frequency — if they are at all.
In its report, the NTSB said that could have played a role in the Soldotna crash.
“The airplanes departed from different locations, about 4 nautical miles apart, about the same time. They flew on converging flight paths for about 2 minutes until the collision,” the report said. “If a CTAF area had been established for the Soldotna area and a requirement had been in place for pilots to communicate their positions when entering the CTAF, the accident may have been avoided.”
Minelga said pilots in the Soldotna area are generally good about reporting on the CTAFs and letting other pilots know they’re in the area.
“But those are the local pilots,” he said. “If you have someone flying from a different area, you might not necessarily know.”
In addition to its suggestion about reporting, the safety board recommends the FAA designate single frequencies so pilots are on the same wavelength.
Minelga said that’s a conversation pilots have had locally before.
“There was a move by some of the people in the Experimental Aircraft Association chapter to actually designate an area around Soldotna bigger than the airport traffic area to have it on 122.5 and to kind of formalize the process where we are actually informally now,” he said, adding that the effort stalled out.
As for the reporting requirement, Minegla said he thinks it’s a good idea, from a pilot’s standpoint. He has multiple radios in his own plane and an Automatic Dependent Surveillance-Broadcast, or ADS-B — a technology that allows aircraft to send and receive three-dimensional data about where planes are in the airspace. It’s also not required by regulators.
But he said a mandate might be unenforceable. For example, not all pilots have radios. And it’s unclear how often pilots should have to announce themselves on the frequency.
“It’s not as easy as it sounds,” he said. “It never is.”
The FAA said it will review the NTSB’s recommendations.
