At 0803 Western Standard Time on 24 April 2005, an Airbus
Industrie A340-212 (Airbus) aircraft, registered ZS-SLA, with a
crew of 11 and 219 passengers, landed short of the displaced
threshold on runway 21 at Perth Airport, Western Australia. The
aircraft was on a scheduled flight from Johannesburg, South Africa.
The pilot in command was the handling pilot for the approach and
landing at Perth.
The displaced threshold was required during Stage 3 of works
involving the reconstruction of runway 06/24 and taxiway
intersections at Perth airport. On 1 December 2004, the airport
operator issued Method of Working Plan (MOWP) YPPH 01/04 which
described the proposed works. The MOWP was distributed to air
operator users of Perth Airport, including the operator of the
Airbus.
The MOWP provided information that Stage 3 works included
reconstruction of the runway 03/21 intersection. The Stage 3 works
were scheduled between 0130 and 0930 on each programmed workday.
During the Stage 3 work periods, the threshold of runway 21 was
displaced 1,331 m to the south, and the glidepath component of the
runway 21 instrument landing system was not available. A temporary
precision approach path indicator (PAPI) was also installed on the
eastern side of runway 21 to provide visual guidance for a 3-degree
approach to the touchdown zone for the displaced threshold. The
temporary PAPI was 395 m to the south of the runway 21 displaced
threshold. Refer to Appendix A for a diagram of the displaced
threshold arrangements for Stage 3 of the works.
The PAPI system consisted of a bar of four light-emitting units
adjacent to runway 21. Each unit of a PAPI system produces a light
beam that is divided into an upper white and a lower red sector. A
pilot sees the four individual lights in a combination of red and
white depending on his vertical position in relation to the
approach slope. If an aircraft is descending on the correct
approach slope, a pilot will see red beams of light projected from
the two inner boxes, and white beams projected from the two outer
boxes. If the aircraft is too high in relation to the approach
slope, the pilot will see white beams of light projected from all
four boxes. Conversely, if the aircraft is too low in relation to
the approach slope, the pilot will see red beams of light projected
from all four boxes.
The MOWP included information that visual ground aids associated
with the works would be supplied, marked, and located in accordance
with the Civil Aviation Safety Authority (CASA) Manual of Standards
Part 139 Aerodromes.
CASA also published a Manual of Operational Standards. Part 3 of
that manual related to aerodromes, and included the following
advice in the introductory material relating to the marking of
displaced thresholds:
During a landing approach, a pilot attempts to create a standard
approach situation using information from, among other things,
cockpit instruments, glideslope guidance and runway aspect and
markings. When a pilot sees the runway picture he/she expects to
see during his/her scan of these inputs, any unobtrusive temporary
markings outside his/her normal areas of concentration may not cue
him sufficiently to make him react to them. Temporarily displaced
threshold markings must compete with normal threshold markings,
centreline markings, fixed distance and touchdown zone markings,
visual glidepath information and all the other visual inputs which
tend to guide a pilot to a touchdown zone close to the approach end
of the visual runway. These existing cues must be disrupted and the
temporary markings made obvious enough to direct the pilots
attention to the displaced threshold.
Paragraph 3.3.1.1 of the CASA Manual of Operational Standards
stated that temporarily displaced thresholds on runways that do not
display permanent threshold markings shall be marked by V-bar
markers on each side of the runway. During the Stage 3 works, four
red and white cone-shaped unserviceability markers were placed over
the threshold markings, and four red and white cone-shaped
unserviceability markers were also placed across runway 21,
immediately to the north of the intersection of taxiway D with
runway 21. Four unserviceability crosses were placed on runway 21
between the permanent threshold and the intersection of taxiway
D. Unserviceability crosses were also located adjacent to the
runway between the intersection of taxiway D and the intersection
of runway 06/24. The portion of runway 21 between the intersection
of taxiway D and the displaced threshold was available for aircraft
to taxi to the take-off point. That portion of the runway surface
was not marked with unserviceability crosses. There were, however,
unserviceability crosses adjacent to the shoulders of that portion
of the runway.
The MOWP included details of the notice to airmen (NOTAM) to be
issued for each stage of the works. The works safety officer was
responsible for initiating the appropriate NOTAMs, through the
Australian NOTAM Office, 48 hours before the commencement of a
particular works stage. The Stage 3 NOTAM included details of the
linear displacement of the threshold of runway 21, and that the
displaced threshold would be marked by five green lights on either
side of the runway and also with V-bar markers. The NOTAM included
information that the runway 21 glidepath was not available. It also
included information about the location of the temporary PAPI, that
the temporary PAPI would be set to Stage 2 intensity, and that 5
minutes notice would be required to change the intensity of the
PAPI. There were no requests made to alter the intensity of the
PAPI setting during the aircrafts approach to runway 21.
The Airservices Australia Manual of Air Traffic Services
contained information on the intensity of precision approach
lighting systems. Stage 2 was the preferred initial selection for
fine, night, overcast conditions. Stage 4 was the preferred initial
selection for fine, day, overcast conditions, while Stage 6 was the
preferred initial selection for bright, clear, day conditions.
The pre-flight NOTAM briefing package supplied to the crew of
the Airbus before the departure from Johannesburg included the
NOTAM relating to the Stage 3 runway 21 displaced threshold at
Perth.
At about 4,000 ft during the descent into Perth, the air traffic
controller cleared the crew to make a visual approach to runway 21.
The crew subsequently reported that, although they were aware of
the displaced threshold, they could not identify the displaced
threshold markings during the approach. The crew asked the
aerodrome controller to confirm the location of the displaced
threshold, and the controller advised the crew that it was to the
south of the intersection of runway 06/24. The pilot in command
adjusted the approach flight path accordingly. The crew then
observed what they perceived to be a transverse white line across
the runway just to the north of the intersection of runway 06/24.
Because the perceived line was close to the intersection of runway
06/24 referred to by the controller, the crew assumed the line to
be the displaced threshold. The crew observed that the runway was
clear of machinery and personnel, and the pilot in command landed
the aircraft just past the perceived transverse line.
As the aircraft passed over the perceived line, and just before
touchdown, the pilot in command saw that the perceived line
consisted of cone-shaped unserviceability markers. The actual
touchdown point of the aircraft was about 670 m short of the
displaced threshold delineated by the V-bar markers on each side of
the runway, and 1,065 m from the temporary PAPI touchdown area
(refer Appendix A). The crew subsequently reported that at no stage
during the approach did they see any other markings that delineated
the displaced threshold. They also reported that they could not
distinguish the V-bar markers referred to in the NOTAM.
The aircraft ran over one of the red and white cone-shaped
unserviceability markers during the landing (see figure 1).
However, the aircraft was undamaged, and there was no other
damage.
Figure 1: Damaged cone-shaped boundary
marker
There was 10 km visibility at Perth at the time of the
occurrence, with 7 oktas (7-eights of total sky visible to the
celestial horizon) of stratocumulus cloud at 5,000 ft above mean
sea level.
Two days after the occurrence, the aerodrome operator amended
its procedure for daytime opening of the displaced threshold on
runway 21. The amended procedure included a requirement for the
temporary PAPI to be set to Stage 6 intensity when the runway
lights were turned off at first light.
The ATSB received no other reports of aircraft landing short of
the displaced threshold on runway 21 at Perth during the period in
which the Stage 3 works were conducted.
