Breakdown of co-ordination between a Boeing Co 737-476 aircraft, VH-TJG and a Pilatus PC-12, VH-FMC aircraft, Adelaide Airport, SA, 26 September 1998

The crew of a Boeing 737 (B737) was cleared by the Adelaide
surface movement controller (SMC) to taxi to the Foxtrot 5 holding
point for runway 05, and to cross runway 30. Earlier, the SMC had
been issued with a blanket clearance by the aerodrome controller
(ADC) that allowed aircraft to occupy or cross runway 30 without a
specific clearance from the ADC. The use of a blanket clearance
reduced the need for segmented taxi clearances.

There were three personnel rostered for duty in the control
tower; an ADC, a SMC and a tower coordinator. At the time of this
occurrence the tower coordinator was absent from the tower cabin,
reducing the monitoring potential of tower staff. All staff were
appropriately trained and rated.

While the SMC was issuing the taxi clearance to the crew of the
B737, the ADC was arranging departure instructions for a Pilatus
PC12 from runway 30. The ADC subsequently cleared the Pilatus to
take off from runway 30, without first cancelling the blanket taxi
clearance and resuming control of the runway. Shortly after issuing
the take-off clearance, the ADC became involved in communications
with the approach controller regarding other inbound aircraft. The
SMC was occupied with other data processing duties.

The crew of the B737 had sighted the Pilatus in the lined-up
position on runway 30, but was unaware that a take-off clearance
had been issued to that aircraft. As the B737 approached the
crossing point of runway 30 on taxiway Foxtrot 2, the crew saw the
Pilatus commence to takeoff. They applied heavy braking and stopped
their aircraft with the nosewheel 1-2 m beyond the runway holding
point. The Pilatus continued its take-off run. The crew of the B737
subsequently confirmed with the SMC that they had been cleared to
cross runway 30.

The local procedures in the Adelaide tower for a blanket
clearance of a runway release required the use of a bright yellow
coloured flight progress strip with the words "RUNWAY 12/30
OCCUPIED". Although a strip was correctly placed in each of the
strip presentation bays in front of both the SMC and the ADC to
indicate that a blanket clearance was issued, that procedure failed
to attract the attention of the ADC.

The investigation of this occurrence was carried out by
Airservices Australia, monitored by a Bureau investigator. A number
of significant factors were identified.