Fairchild Industries Inc SA227-AC, VH-EES

Investigation number

200102139

Occurrence date

15/05/2001

Location

Sydney, Aero.

Report release date

23/07/2002

Report status

Final

Investigation type

Occurrence Investigation

Investigation status

Completed

Aviation occurrence type

Loss of separation

Occurrence category

Incident

Highest injury level

None

Safety Action Significant Factors Analysis Summary

Local safety action

As a result of the investigation, Airservices Australia advised
that they were proposing a change to procedures in AIP and MATS.
The changes proposed were to place the responsibility onto the
pilot or vehicle driver receiving the conditional clearance to
identify and avoid the aircraft or vehicle causing the conditional
clearance, prior to proceeding, rather than relying on an
implication that it was their responsibility. The other significant
change proposed was to include "position" as a requirement of the
conditional clearance. The proposed amendments were to be included
in both MATS and AIP for consistency. As of 6 May 2002, the changes
had been drafted for the final consultation process.

The aerodrome controller was relatively busy and involved with
multiple tasks prior to the occurrence. Both of the incident
aircraft had been holding for a lengthy period and the controller
was attempting to expedite each of their departures. By issuing a
conditional clearance to the pilot of the Titan, the controller
achieved two outcomes. First the pilot was tasked to line up, which
would expedite the aircraft's departure and notify the pilot that
he was next. Secondly, the controller, in effect, transferred his
responsibility for separation to the pilot by making the clearance
conditional. The condition of the clearance was that the pilot
would monitor the departing aircraft and line up behind it. That
distanced the controller from the responsibility of watching and
waiting for the Metro to roll for take off and then telling the
Titan pilot to line up after the Metro had passed the intersection.
The delegation of responsibility allowed the controller to
concentrate on other tasks in the tower, such as the monitoring and
control of taxiing aircraft around the tarmac area during the works
in progress.

The Metro had been holding for departure for a significant
period. The crew, when eventually cleared to line up and
subsequently take off, responded quickly and accurately to fit in
with what appeared on radio to be a busy and complex period. The
controller sounded confident in the various instructions being
issued and the crew would not have expected an aircraft to line up
in front of them. The crew did not comprehend that the readback of
the conditional clearance included advice that the Titan was at the
Foxtrot intersection and was lining up. Their focus, once cleared
for takeoff, would have been on takeoff checks and their departure
profile.

The Titan had been holding for over 10 minutes and the pilot
would have been keen to depart. He would not have been aware that
the Metro was holding at the threshold of runway 16R. The Metro
would have been difficult to see as its external lights would have
blended in with the airfield lighting and the lights of Sydney to
the north of the airport. When the Metro was cleared for takeoff,
because its position at the threshold was not annunciated by the
controller and it was during the curfew period, the Titan pilot
assumed the aircraft was departing from taxiway Golf. While the
lights of the Metro would not have been obvious to the Titan pilot
when he looked briefly to the right as he began to enter the
runway, the landing lights should have been seen. Nevertheless,
they may not have been obvious if they were directed away from the
runway centreline while the Metro was still in the process of
lining up.

A Fairchild SA227-AC (Metro) aircraft was cleared to take off
from runway 16R at Sydney. A Cessna 404 (Titan), holding at the
Foxtrot intersection with runway 16R, was cleared to line up behind
the departing Metro. The Titan pilot acknowledged the conditional
clearance and reported lining up at Foxtrot. As the Metro was
rolling under take off power, the pilot noticed the Titan moving
onto the runway. The Metro pilot veered the aircraft sharply to the
right to avoid a collision and passed the Titan at 77 kts. The
wingtip clearance between the two aircraft was estimated to be 6m.
The takeoff was aborted.

The investigation revealed that the Metro was cleared by air
traffic control at 22:44 Eastern Standard Time to taxy to the Bravo
One holding point on runway 16R. The aircraft was on a night
freight operation to Brisbane and had two pilots on board. Bravo
One was the most northerly of the taxiways on the eastern side of
the north-south runways. The Bravo One taxiway entered runway 16R
at the threshold allowing the full length of the runway for
takeoff. The co-pilot reported ready for takeoff at 22:47:51, which
was approximately 12 minutes before curfew. The Metro had taxied
behind a Boeing 727 that was to depart first.

Aircraft movements between 23:00 and 06:00 local time at
Sydney's Kingsford Smith Airport were regulated by the Sydney
Airport Curfew Act 1995, the Sydney Airport Curfew Regulations and
the Air Navigation (Aerodrome Curfew) Regulations. Aircraft that
received a taxi clearance prior to 23:00 but subsequently departed
after commencement of the curfew period were able to use the full
length of the runway and were not required to reposition south of
the intersection of runway 16R and taxiway Golf. However, aircraft
that taxied after 23:00 were required to take-off from a position
south of the intersection of taxiway Golf. That requirement was to
minimise environmental noise in the residential areas to the north
of the airport.

At 22:52:15, the controller had cleared the Boeing 727 to take
off when the pilot of the Titan called for a taxi clearance. The
Titan was scheduled for a single-pilot night freight operation to
Canberra. The pilot of the Titan was instructed by the controller
to stand by. Due to arriving traffic on runway 34L, the crew of the
Metro was advised that a delay of around 10 minutes was probable.
The Titan was then cleared to the taxiway Golf intersection, which
was immediately changed to the taxiway Foxtrot intersection. The
Foxtrot intersection was closer to the Titan's parking bay. Because
the clearance was issued 7 minutes prior to curfew, taxiway Golf
was not required for noise abatement purposes. The B727 departed
and the controller then processed two other aircraft for landing on
runway 34L before the Metro was cleared to line up at 23:04:12.

During the approximately 17-minute period that the Metro was
waiting at the holding point, the controller made numerous
transmissions to seven other aircraft, as well as the coordination
with controllers in the Sydney terminal control unit. In addition,
the controller had discussed the closures of taxiways with the
safety officer in "Car 3" and had cleared an aircraft under tow on
the north-east apron. All transmissions made by the controller
sounded professional and confident.

When the second of the two landing aircraft had vacated runway
34L at taxiway Bravo 9, the Metro was cleared to take off from
runway 16R. The clearance was issued at 23:05:00 and acknowledged
by the pilot. Almost immediately, at 23:05:07, the pilot of the
Titan was issued a conditional clearance to line up. The clearance
was: "CSV, Metro departing, behind that aircraft line up". The
pilot replied "Behind the Metro holding clear Foxtrot at the
moment, lining up, CSV". Less than 30 seconds later, the Metro crew
reported aborting takeoff.

Neither the Metro pilot nor the controller understood that the
Titan pilot had said that he was lining up at the Foxtrot
intersection during the read back of the conditional clearance. The
replay of the audio recording confirmed that the Titan pilot's
readback transmission was difficult to understand.

The controller in the tower was working the combined position of
aerodrome control and surface movement control. Although five
controllers were rostered for duty until 2300, three had stood down
earlier; after the last international aircraft had departed. Such a
reduction in staff coverage was common practice. The other
controller was absent from the tower on a break. The occurrence
happened at night in clear weather conditions. Works in progress on
the north-east sector of the airport increased the normal lighting
within the area with a number of flashing lights and lighting
towers.

The Titan pilot said that he understood that the line up
clearance was a conditional clearance but had thought the Metro was
departing from taxiway Golf because they were in the curfew period.
He looked right and left when entering the runway but did not see
the Metro, which was using the full length of the runway. The
Foxtrot intersection was 462 m from the runway threshold and the
Golf intersection was 1039 m from the runway threshold.

During discussions with the Metro crew, the pilot in command
reported that all of their aircraft's external lighting was
selected on, including the landing lights. After veering to the
right to miss the Titan that was lining up, the pilot considered
the takeoff to be unstable and, therefore, aborted the departure.
The aircraft returned to the apron.

The Manual of Air Traffic Services (MATS) stated at 6.3.8.2:

"An aircraft delayed by the traffic situation shall be issued
traffic information if appropriate, and instructed to hold position
off the runway, or shall be issued a conditional line-up
clearance".

MATS did not provide a definition of a conditional clearance.
However, there was a definition a conditional line-up clearance in
the Aeronautical Information Publication (AIP).

The AIP 3.4 - 14 at paragraph 4.5 defined Conditional Clearances
as follows:

"Phrases such as "behind landing aircraft" or "after departing
aircraft", will only be used for movements affecting the active
runway(s) when the aircraft or vehicles concerned are seen by the
appropriate controller, pilot or vehicle driver. In all cases, a
conditional clearance will be given in the following order and
consist of:

identification;
the condition (specify); and
the clearance, eg:

ATS: "(aircraft callsign) A340 ON SHORT FINAL, BEHIND THAT
AIRCRAFT LINE UP".

Pilot: "BEHIND THE A340 LINING UP (aircraft callsign)".

Note: This implies the need for the aircraft receiving the
conditional clearance to identify the aircraft or vehicle causing
the conditional clearance."

Aircraft Details

Manufacturer

Fairchild Industries Inc

Model

SA227

Registration

VH-EES

Operation type

Air Transport Low Capacity

Departure point

Sydney, NSW

Destination

Brisbane, QLD

Damage

Nil

Aircraft Details

Manufacturer

Cessna Aircraft Company

Model

404

Registration

VH-CSV

Serial number

4040217