Investigation number
199502903
Occurrence date
State
Victoria
Report release date
Report status
Final
Investigation type
Occurrence Investigation
Investigation status
Completed
Aviation occurrence category
Near collision
Occurrence class
Incident

VH-PZN was cleared from Mansfield to Melbourne at 4,500 ft. 30 miles northeast of Melbourne, VH-PZN advised approach radar of sighting an unexpected light aircraft, head-on at the same altitude. To avoid a collision, VH-PZN descended immediately and passed approximately 300 ft below and about 100 metres abeam the other aircraft. The unidentified aircraft did not show up on radar as a secondary surveillance radar (SSR) return. After the breakdown in separation, its primary return was plotted by the radar controller. All attempts by Air Traffic Services (ATS) to contact the aircraft by radio were unsuccessful until the aircraft subsequently called Melbourne radar advisory service (RAS) landing at Wallan. In the meantime, a Piper PA34 assisted ATS by following the aircraft and identifying it as VH-TOF. The pilot of VH-TOF subsequently advised that he did not see or hear VH-PZN at any time. He advised that he had been viewing property on the ground from above. He did not believe that he had climbed above 4,000 ft at any stage of his flight. Both aircraft were flying in accordance with visual flight rules (VFR) in visual meteorological conditions (VMC) with a cloud base of 5,000 ft above mean sea level (AMSL). Significant Factors The following factors were considered relevant to the development of the incident: 1. The pilot of VH-TOF probably inadvertently climbed above 4,000 ft. 2. No SSR transponder returns were received from VH-TOF. 3. VH-TOF was not monitoring Melbourne radar advisory service frequency 135.7 MHZ within 35 miles radius of Melbourne until arrival at Wallan.

Aircraft Details
Manufacturer
Piper Aircraft Corp
Model
PA-28-140
Registration
VH-TOF
Sector
Piston
Departure point
Coldstream VIC
Destination
Wallan VIC
Damage
Nil
Aircraft Details
Manufacturer
Piper Aircraft Corp
Model
PA-28-161
Registration
VH-PZN
Sector
Piston
Departure point
Mansfield VIC
Destination
Melbourne VIC
Damage
Nil