Mat Su Area Traffic Frequencies: Your input needed

A group of industry and government stakeholders is working to reduce the risk of mid-air collisions in the Mat Su Valley, but they need your help to reach that objective.  Over the past five months, the working group has taken the results of last summer’s AOPA pilot survey and inputs from pilots who fly in and through the area.  The goal is to clarify the use of radio frequencies used to maintain situational awareness when operating in this busy airspace.

Home to over two hundred private and public use airports, airstrips, lakes and landing areas, the Mat Su experiences a wide range of aviation uses.  The airspace in the valley sees everything from private pilots heading to cabins or hunting and fishing areas, to commercial operators hauling visitors, groceries and supplies to remote lodges and mines. It is also used for military training flights at low-level by helicopters and C-17s, and student flight training from Anchorage and valley airports. Add to the list, those of us that fly through the Mat Su headed to more distant destinations.  One of the tools we use to share the airspace is reporting our location and listening for nearby aircraft, but on what frequency?

Rex Gray's map showing overlapping CTAF frequencies.

Rex Gray’s map showing overlapping CTAF frequencies.

During the “inventory” phase of this project, it became apparent there was a lack of agreement even among seasoned professionals on what radio frequency to use for situational awareness in different parts of this airspace.  Rex Gray, a valley resident who also serves as the President of the Alaska Airmen’s Association, took the time to sit down with the Anchorage Sectional and the Alaska Supplement and map out overlaps in CTAF coverage in the valley.  According to the AIM, a Common Traffic Advisory Frequency serves an area 10 miles around its assigned airport.  This map, coupled with other area frequency guidance in different publications highlighted the problem. 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.  A priority was identified within the working group to reduce this confusion, and promote the use of defined area frequencies, as has been done on a case by case basis in other parts of the state.

Developing a plan that would address the diversity of users is a challenge.  Over the past two months, using Google Earth as a tool, the group developed a number of scenarios to identify areas that might share a common frequency.  Subsequently, these were reduced to two scenarios which are still in need of refinement before focusing on a final course of action.

Scenario which assigns frequencies to different zones in the Mat Su Valley.

Scenario which assigns frequencies to different zones in the Mat Su Valley.

Area Frequency Scenario: This option would assign the frequency 122.9 to the zone west of the Susitna River, to the flanks of the Alaska Range. It also cuts across the lower valley, to accommodate traffic that departs Anchorage headed northwest.  A second zone, running along the Parks Highway toward Talkeetna under this scenario would use 122.8.  The zones around Palmer and Talkeetna, with part time Flight Service Stations, would use the FSS Advisory Frequency, 123.6.  These proposed zones would connect to other areas, such as the Cook Inlet Area Frequency to the west and the Knik Glacier advisory frequency, both of which use 122.7.  Northwest of Talkeetna, a Mountain Traffic Frequency of 123.65 has been in use for years to accommodate the aircraft hauling climbers and flightseeing visitors between Talkeetna and the Alaska Range.

Scenario that provides a discrete frequency above 2,000 ft to reduce congestion on 122.8.

Scenario that provides a discrete frequency above 2,000 ft to reduce congestion on 122.8.

Vertical Area Frequency Scenario:  In the second case, the zones to the west and around Palmer and Talkeetna (described above), would remain the same. The frequency 122.8 would still serve the area along the Parks Highway, but aircraft operating between 2,000 and 5,000 feet MSL would have the option to use a discrete frequency, we’ll call it 122.XX, to reduce the frequency congestion from the traffic flying in airport traffic patterns and at lower altitudes in the zone.

What happens after I leave a zone?  Several people have raised the question of what happens once you leave one of these zones. At that point, pilots would resort to the standard rules involving CTAF’s.  Chapter Four in the AIM addresses this topic. Section 4-1-9 defines the protocol for traffic advisory practices for airports without facilities:  Within 10 miles of the airport or landing area, monitor and communicate on the designated CTAF.  Section 4-1-11 indicates that an airport with no tower, FSS or Unicom should use the multi-com frequency 122.9.  Table 4-1-2 indicates that for air-to-air communication, the FCC has authorized the use of 122.75, which helps keep the chatter down on the other frequencies in congested airspace. Checking the Alaska Supplement Notices Section is a good idea, as a number of areas around the state have had special area frequencies assigned.

These scenarios are still taking shape. AOPA would like to hear your thoughts on these approaches to reducing the confusion on radio frequency usage in the Mat Su Valley. Please email your comments to:  If you attend the Alaska Airmen’s Great Alaskan Aviation Gathering this weekend in Anchorage, stop by the AOPA booth and look at these scenarios in more detail.  While this work continues, fly with your lights on, keep your eyes out of the cockpit and fly safe!