Mode C Intruder Alert Services - Point Mackenzie Area

Northwest of Anchorage, Alaska

MODE C INTRUDER ALERT is a function of certain air traffic control automated systems designed to alert controllers to existing or pending situations between a tracked target (a known IFR or VFR aircraft) and an untracked target (an unknown IFR or VFR aircraft equipped with an operating Mode C transponder) that requires immediate attention/action.

Mode C Intruder Alert provides an aural and associated visual alert that produces enlarged and blinking alphanumeric data blocks on the controller’s radar display. Due to the close proximity of aircraft, the enlarged and blinking data blocks may make the radar unusable and the associated aural alarm distracts the controller from performing air traffic control duties.

During periods of high air traffic activity in the vicinity of Point Mackenzie, Anchorage Approach Control may temporarily disable the Mode C Intruder Alert function within one or both of the following areas:

Region 1: A dual range, dual azimuth area, based upon the Anchorage Airport Surveillance Radar (ASR) antenna, from 285° magnetic to 007° magnetic, between 3.66 nautical miles and 10 nautical miles, and from the surface up to and including 1,000 feet above ground level (AGL).

Region 2: From the surface up to and including 2,100 feet AGL within a polygon defined by the following latitude/longitude points:

A message will be broadcast on the Anchorage ATIS, Lake Hood ATIS, and MRI ATIS when the Mode C Intruder Alert function is disabled.

Mode C Alert Inhibit Region 1

Mode C Alert Inhibit Region 2