An ATSB investigation report into a near-collision at Geraldton Airport released last week found that buildings prevented effective communications between two aircraft taking off on separate runways.
The incident occurred in March last year between Metroliner VH-KGX taking off on runway 03 and A36 Bonanza VH-CKX departing on runway 14. The two aircraft rolled within 3 seconds of each other and got as close as 319 metres horizontally and 250-300 feet vertically as the Metroliner passed in front of the Bonanza.
Although the runways don't intersect, the climb-out path of runway 14 crosses runway 03.
ATSB investigators found that the two pilots could not see each other and buildings at the airport shielded VHF transmissions, requiring a third party to relay messages.
"Each aircraft was unable to verify the other’s location while lined up for take-off,” ATSB Director Transport Safety Kerri Hughes said.
“While the third aircraft pilot was attempting to assist, the details provided were inaccurate and incomplete, which inadvertently resulted in misinterpretation by the Metroliner and Bonanza pilots, influencing their almost simultaneous decisions to take off.”
The pilots of both aircraft made CTAF calls, and after reaching their respective thresholds, attempted to establish radio contact with the other. Neither was able to do so, and neither pilot could see the other.
The pilot of C172 VH-MVQ, was holding short of runway 14, and attempted to assist by providing traffic information to both aircraft. The Cessna pilot’s last traffic advice was not addressed to a particular aircraft and advised that both aircraft were holding short for each other.
The Bonanza pilot broadcast that they were rolling on runway 14, which was followed immediately by the Metroliner pilot broadcasting that they were rolling on runway 03. Neither pilot heard the other pilot’s rolling call.
GA-8 Airvan VH-AVP was waiting in line behind the Cessna and the pilot reported that when they became aware of a potential conflict they made a transmission to alert the Bonanza pilot. The Bonanza had advanced 100 m along the runway, but the pilot did not hear the Airvan pilot's warning and continued the take-off.
The Metroliner pilot heard the call, however, as they were past their low-speed abort regime, they elected to continue their take-off.
The Metroliner entered the runway 14 strip about 400 m ahead of the Bonanza, with a vertical separation of 250–300 ft. Once both the Bonanza and Metroliner were airborne, the pilots were able contact each other.
Investigators noted in the report that the operators of both aircraft have brought to the attention of their flight crews the potential for VHF shielding at Geraldton and the need to act with caution.
Geraldton Airport has also submitted an amendment to ERSA warning of the potential for shielding.
The full report is on the ATSB website.