Mode C Intruder Alert Services - Lake Hood Seaplane base

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 may distract the controller from performing air traffic control duties.

During periods of high air traffic activity, Lake Hood Tower may elect to temporarily disable the Mode C Intruder Alert function within the Lake Hood Segment (as described in 14 CFR 93.55) below 2,029 feet AGL. Suspensions of Mode C Intruder Alert service will be broadcast on the Lake Hood ATIS.

graphic depicting Mode C Intruder Alert Inhibit Region Surface to 2,029 feet.

(AAL-530, 8/7/01)