Aviation safety investigations & reports

Loss of separation involving a The Boeing Company 737-476, VH-TJE, Perth, Aerodrome, WA on 10 June 1998

Investigation number:
199802100
Status: Completed
Investigation completed

Summary

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The aerodrome controller (ADC) at Perth tower had cleared the Boeing 737 to line up on runway 21. An Airservices Australia car was accompanying the airfield mower cutting grass at the runway's edge, approximately midway along the runway. The ADC was aware that the car was just within the flight strip but he was not aware of the existence of the mower. Only after he cleared the 737 to take off and it had begun rolling, did he become aware of the mower and its close proximity to the runway. He instructed the pilot of the 737 to cancel the takeoff. The surface movement controller (SMC), who had not heard the take-off clearance, became aware of impending confliction when the aircraft began rolling. He instructed the car to vacate the flight strip. The aircraft stopped approximately 600 m before the original position of the mower having rolled approximately 750 m. The mower was a small blue vehicle and was approximately 1500 m from the tower and would have been difficult to see from the tower. The ADC had taken over the position approximately 10 minutes prior to the incident. He reported that he could not recall being advised about the mower during the handover so the ADC was unaware of the mower's existence. However, the "runway occupied" strip had been placed in the ADC's departure runway designator console but because the ADC did not post the aircraft's flight strip on the console before clearing the aircraft for take-off, he did not note that the mower's operation near runway. The manual of air traffic services (MATS) details a requirement that an aircraft not be issued with a take-off clearance until its flight strip has been placed under the "runway occupied" strip at the ADC console and the runway has been vacated. When the ADC issued the take-off clearance, he had assumed that the SMC had ensured that the runway was vacated although he had not coordinated with the SMC to ensure that such was the case. The tower coordinator normally supervised the operations within the tower but he was pre-occupied at the time recording information for the automatic terminal information service (ATIS). He had, therefore, not noticed the incident developing until the aircraft had begun its take-off run. He reported that he then called to the ADC to stop the aircraft because there was a vehicle on the runway. LOCAL SAFETY ACTION Airservices Australia has issued a local instruction highlighting the necessity of full handover procedures and a requirement to address escort vehicles with their callsign and escorted company on all radio communications and during tower coordination.
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General details
Date: 10 June 1998   Investigation status: Completed  
Time: 10:30 WST    
State: Western Australia   Occurrence type: Loss of separation  
Release date: 06 August 1998   Occurrence category: Incident  
Report status: Final    

Aircraft details

Aircraft details
Aircraft manufacturer The Boeing Company  
Aircraft model 737-476  
Aircraft registration VH-TJE  
Sector Jet  
Damage to aircraft Nil  
Departure point Perth WA  
Destination Sydney NSW