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Signals crossed for pilots flying over Alaska's Mat-Su region

Colleen Mondor
Pilots, take note: there is a dangerous overlap of the Common Traffic Advisory Frequencies (CTAFs) that coupled with the busy summer flying activity have made the Mat-Su region a potential breeding ground for accidents. Jeffrey Schäfer photo

Pilots who fly in the Mat-Su region north of Alaska's largest city should take note of potential changes to radio frequency use in their area. To one degree or another, there is a dangerous overlap of the Common Traffic Advisory Frequencies (CTAFs) that coupled with the busy summer flying activity has become a breeding ground for accidents. 

In an attempt to mitigate safety concerns, an effort has been underway for some time with multiple industry and government representatives to “identify inconstancies and confusing guidance concerning CTAF frequencies, and then provide the FAA with suggested recommendations to establish effective advisory radio frequencies.” Collectively known as the Mat Su Mid-Air Collision Working Group, they include the FAA, AOPA, Alaska Airmen’s Association and the Alaska Aviation Safety Foundation.

Dee Hansen with the Airmen’s Association and Tom George with AOPA have been leading a group “focused specifically on the Mat Su radio frequency guidelines, and related issues.” A vital part of their efforts includes a survey distributed to airspace users  last year that was developed to assist in forming a solution to the group’s situational awareness concerns.

The working group was formed in response to a devastating mid-air collision on July 30, 2011 near Amber Lake, about 16 miles southwest of Talkeetna. In the accident, which involved a Cessna 206 and Cessna 180, the pilot and sole occupant of the C206 survived while all four of those onboard the C180 were killed. In the recently released factual report for the accident, the NTSB found that the C206 pilot was transmitting position reports and monitoring on 122.8 MHz, the CTAF frequency designated for the area. The C206 pilot stated to the NTSB that he was did not hear the C180 pilot on that frequency. A pilot-rated family member of the C180 pilot told the NTSB that he was known to use 122.9 MHz while operating around remote lakes. Neither pilot apparently saw one another prior to the aircraft colliding.

“There’s a lot of confusion,” says working group member Danny Davidson, who is with the Alaska Air Carriers, “and pilots need to know how to interpret what they are being told. Many of them don’t know they are misinterpreting the CTAF assignments and they won’t find out until it’s too late.”

There are more than 200-plus private and public airports, airstrips, lakes and military and civilian landing areas in the Mat-Su. CTAFs serve a ten-mile radius around an assigned field where no control tower exists. With so many fields so close together, Mat Su pilots using the frequency for their departure or destination field often share airspace with aircraft intent on sites nearby who could be communicating on a different frequency.

As explained in a recent post at the Aircraft Owners and Pilots Association (AOPA) Alaska Region page, “Pilots who consciously used the CTAF for the airport they were headed to were often sharing airspace with aircraft on other frequencies enroute to adjacent landing areas.”

Simply put, pilots in close geographical proximity are often not speaking to one other and thus not aware until it’s almost too late that they are sharing airspace.

According to the FAA’s Alaska Supplement, the CTAF for airports south and west of the Parks Highway is 122.8 MHz. The supplement further states that airports north and east of the Parks Highway will be assigned a CTAF frequency of 122.9 MHz. This general assignment changes, however, if an airport has an otherwise assigned CTAF. For example, airports such as Nugget Bench and Skwentna, which are south and west of the Parks Highway, have been allocated radio frequencies of 122.9 MHz.

Aircraft traversing the Mat-Su area and broadcasting their position without awareness of the CTAFs further add to the complications.

“This whole problem is ‘Ambiguity 101,” explains Davidson. “The fastest response would be to put out a NOTAM via Kenai FSS and let pilots know that everything west of the Susitna is to be 122.9. Then the group could work out the rest, but it would prevent accidents this summer.”

Two separate scenarios have been proposed by the working group for splitting the region into assigned CTAF zones that would formally extend the area for each frequency and simplify radio communication. Such changes to standard CTAF rules can be found in other areas of the state where special frequencies are assigned within certain regions. AOPA is looking for input from users on which scenario they believe would be most helpful. The full breakdown can be read on the AOPA website and comments on the issue can be emailed to airtrafficservices@aopa.org.

While the process to alter radio communications in the Mat-Su continues, vigilance in this active aviation environment is key to effective situational awareness. As AOPA’s George makes clear, “While some changes might happen soon, we still have a lot of work ahead to make changes to individual airport CTAF frequencies, and time it to coincide with chart and publication cycles. We anticipate a significant education/outreach effort to accompany the changes, to avoid further confusion.”

Ironically, a process that was designed to simplify the aviation environment and bring clarity to its users has taken an agonizingly long time. With the two-year anniversary of the Amber Lake accident approaching, pilots are rightfully frustrated over delays.

The NTSB expects the Probable Cause determination for the crash to be released in the next few weeks. It is expected to state that both pilots failed to maintain adequate situational awareness of their surroundings. This, of course, is difficult to accomplish when a pilot does not even know where he or she should be looking.

A summary of the Mat Su Mid-Air Collision Working Group survey results can be found here.

Contact Colleen Mondor at colleen(at)alaskadispatch.com