Loss of separation involving a Cessna 152, VH-CSZ and Boeing 727-277, VH-ANA, Canberra, Australian Capital Territory, on 18 May 1995

FACTUAL INFORMATION

When the pilot of the Boeing 727 requested a taxi clearance from bay two for runway 17, the Aerodrome Controller (ADC) issued a clearance to the Surface Movement Controller (SMC) for the Boeing to cross runway 12. The SMC cleared the Boeing to taxi and issued the clearance to cross runway 12.

Other traffic requirements then became the priority for both the SMC and Co-ordinator.

While the SMC was issuing the Boeing 727 pilot with the clearance, the Cessna 152 pilot reported ready for take-off to the ADC. As both aircraft were on different frequencies, neither pilot heard the other. After a short delay, the Cessna was cleared for take-off.

Over the 30 seconds following the issuing of the take-off clearance, the ADC became involved in the co-ordination of three other aircraft. He then noticed that the Cessna had not taken off and reissued the take-off clearance. The Cessna pilot replied, 'We've got the 727 crossing'. At this point the ADC saw the Boeing crossing the runway and instructed the Cessna to hold position.

The second ADC was involved in discussions with surveyors during the entire sequence.

Due to the weather conditions, runway 17 was designated for arrivals and departures, while runway 12 was used for circuit traffic. This runway configuration is not often used in Canberra.

ANALYSIS

The ADC forgot that he had issued the Boeing with the clearance to cross. He was distracted by the presence of visitors in the tower and the busy workload.

The non-standard runway configuration may have had some influence on the ADCs procedures, resulting in a runway scan different to that which he normally would use.

FINDINGS

1. The ADC issued the SMC with a clearance for the Boeing 727 to cross runway 12.
2. The SMC issued that clearance to the Boeing 727 pilot.
3. The ADC issued the Cessna 152 pilot with a take-off clearance from runway 12.
4. The Cessna 152 pilot reported holding while the Boeing 727 crossed the runway.

SIGNIFICANT FACTORS

1. The runway configuration was not standard for Canberra.
2. The ADC was distracted due to a busy workload and the presence of visitors.