The aircraft, operating a scheduled passenger flight from
Singapore to Sydney, landed at Sydney on runway 16R at 0525 Eastern
Standard Time (EST) during curfew hours (All times are EST unless
otherwise stated).
The Bureau of Meteorology (BOM) issued a terminal area forecast
(TAF) for Sydney Airport at 2051 on 14 October 1997 for a 24-hour
period commencing at 2200. The forecast indicated that the weather
at Sydney would be suitable for an approach and landing, with the
wind from 290 degrees at 8 kts. The forecast also indicated that
from 0400 the wind would change direction to 240 degrees and that
the strength would increase to 15 kts with gusts to 25 kts.
The Sydney Airport Weather Briefing issued to the operator by
the BOM at 1745 on 14 October 1997 covered the TAF period from 1600
for 24 hours and indicated that there was a 20% chance that the
change in the wind would be to a southerly direction.
The crew was aware of the TAF information at the pre-flight
briefing at Singapore. As the available forecasts indicated that
conditions would be acceptable for the aircraft to make an arrival
at Sydney using runway 34L, there was no requirement to carry
additional fuel other than company required variable and fixed fuel
reserves. This was in accordance with normal company operating
procedures and fuel planning policy.
The flight departed Singapore at 2217 (2017 local time) and the
flight plan indicated that the aircraft would arrive in Sydney at
0456. During the flight, the crew monitored the hourly
meteorological information broadcasts (VOLMET) and received routine
meteorological (METAR) reports, which were based on Trend Type
Forecasts (TTF), through the Aircraft Communication Addressing and
Reporting System (ACARS) to keep themselves appraised of current
and projected weather conditions at Sydney.
Trend Type Forecasts consist of aerodrome weather reports which
contain a statement of trend. They are issued at 30-minute
intervals and describe significant changes expected to occur during
a 3-hour period. TTFs supersede aerodrome forecasts and the VOLMET
information.
From 0130 the TTF for Sydney Airport included details of the
south-westerly change expected at 0400. At 0333 a TTF was issued
which indicated that the wind at Sydney was 200 degrees at 14 to 18
kts. This TTF, which the crew received via the ACARS, was appended
with the term NOSIG, which indicated that there was no significant
change expected within the next 3 hours. The TTF issued at 0403
indicated that the wind was 190 degrees at 7 to 12 kts and again
included the term NOSIG.
The 0431 TTF reported the wind as 190 degrees at 17 to 24 kts.
These conditions were unacceptable for a landing on runway 34L as
the maximum certified tailwind of 15 kts for this aircraft would be
exceeded. A special aerodrome forecast was issued 3 minutes later
which reported the wind strength as 21 to 31 kts, with a resultant
increased downwind component for a landing on runway 34L.
During aircraft operations, a point in the flight is reached
where the crew need to make a decision to continue to the
destination airport based on the weather and other conditions
prevailing at that time. If conditions are not acceptable for
arrival at the destination airport, the aircraft must proceed to an
alternate airport. This point is usually designated as the decision
point alternate (DPA). The DPA for this flight was Parkes NSW, with
the alternate aerodrome nominated in the flight plan as Melbourne.
At 0422, Melbourne Air Traffic Control (ATC) identified the
aircraft's position on radar as 173 NM from Parkes.
The automatic terminal information service (ATIS) for Sydney was
updated at 0424. This update reported that the wind direction was
from 170 degrees and the strength was 10 to 20 kts with gusts to 25
kts and a maximum downwind component of 25 kts on runway 34L. This
change in the ATIS was passed to the crew at 0426 and to two other
international aircraft approaching Sydney.
The crew of the incident aircraft acknowledged that they had
received this information. Shortly after, the crew advised ATC that
their latest approach time to Sydney would be 0540. They also
advised ATC that they had insufficient fuel to hold until 0600. The
aircraft reached Parkes at 0444, 18 minutes after the new ATIS was
broadcast, and continued towards Sydney.
In response to a query from ATC regarding diverting to Brisbane,
the crew re-calculated the fuel status of the aircraft. Because the
aircraft had passed the DPA, Melbourne was no longer a suitable
alternative destination as there would be an excessive headwind en
route. The crew advised ATC that if they proceeded to Brisbane
immediately, they would have sufficient fuel. ATC asked the
aircraft to stand by. Over the next 4 minutes ATC coordinated other
traffic including aircraft entering holding patterns at Bindook.
ATC subsequently asked the crew whether they intended to divert to
Brisbane and the crew advised that they were now unable to do so as
they had insufficient fuel. The fuel required to divert to Brisbane
from this point was calculated by the crew to be 14,000 kg and
there was only 13,200 kg remaining on board.
The crew informed ATC of the aircraft fuel status and that they
would be proceeding to Sydney. ATC advised the crew that if they
could not hold until 0600 and would therefore land during the
curfew, they would have to declare an emergency. ATC then asked the
crew to confirm that this was what they wished to do, to which the
crew agreed. ATC then processed the aircraft ahead of the other
preceding aircraft. The crew did not use the standard international
phraseology to declare the emergency.
The crew again notified ATC that they could hold until 0540. ATC
advised the crew that there would be no difference if they landed
before this time as they would be landing on runway 16R prior to
the lifting of the curfew.
During descent into Sydney, the crew assessed the possibility of
making an approach to runway 34L, as the wind information from the
aircraft Flight Management System (FMS) indicated that the wind
still favoured an approach to runway 34. Information provided from
Sydney Tower on the actual wind at the runway threshold precluded a
landing on this runway. The aircraft landed on runway 16R at 0525,
with more than the minimum fuel reserves in accordance with company
policy.
