The pilot of a de Havilland Beaver floatplane, registered
VH-AQV, was conducting a charter positioning flight from Hamilton
Island Marina to Whitehaven Beach, Whitsunday Island. At
approximately 1615 Eastern Standard Time (EST), the pilot was
landing the aircraft towards the south, about 600 m off the beach,
to avoid mechanical turbulence associated with terrain at the
southern end of Whitehaven Beach. He reported that the approach and
flare were normal, however, as the aircraft touched down on the
right float, the aircraft swung sharply right and then sharply
left. The left wing contacted the water, and the aircraft
overturned. The pilot exited the upturned aircraft through the left
rear passenger door and activated a 121.5 MHz distress beacon.
The Hamilton Island terminal area forecast (TAF) issued at 0426
EST indicated that the wind was expected to be from 140 degrees at
20 kts. An amended TAF issued at 1043 EST indicated that wind gusts
up to 28 kts were expected. The Hamilton Island automatic weather
station recorded the wind conditions at 1600 EST as 130 degrees at
26 kts, gusting to 30 kts. The pilot reported that the visibility
and general weather conditions were good. There was a slight
crosswind from the right and light to moderate turbulence during
the approach and landing. He described the sea state as a light
swell with significant chop.
The accident flight was the pilot's last of 6 flights into
Whitehaven Beach that day. He reported that conditions had remained
much the same throughout the day. Another company aircraft had
taken off from Whitehaven Beach about 5 minutes before the
accident.
The pilot had accrued a total of 486 hours in floatplane
aircraft and approximately 1500 water landings, almost all of which
were conducted onto still water. He had been with the company for
about 1 month at the time of the accident, and had accrued a total
of about 50 hours on the Beaver aircraft, almost all on the
accident aircraft.
The aircraft was fitted with floats that were larger than
standard, in accordance with a supplemental type certificate. The
floats extended further forward than standard floats, and the
aircraft's centre of gravity was generally close to the forward
limit at light weights. The aircraft manufacturer advised that the
aircraft "would require a much greater nose-up pitch attitude" on
landing than a Beaver aircraft equipped with standard floats.
The pilot cancelled SARWATCH prior to landing as there was no
Very High Frequency (VHF) radio coverage once the aircraft was on
the water. After the aircraft had overturned, the pilot had no
means of communication, other than the distress beacon. The
passengers waiting on the beach had no means of communication with
either the pilot or the company. When the company did not receive a
departure radio report from the pilot, another company aircraft
diverted to the area and located the overturned aircraft. The pilot
was rescued from the aircraft by a company helicopter approximately
2 hours after the accident.
At 1637 EST, Australian Search and Rescue (AusSAR) identified an
extremely poor quality distress beacon signal located 94 km south
of Mackay (194 km south of Whitehaven Beach). The detected signal
was of poor quality, most likely because of the position of the
satellite relative to the beacon. Another satellite in a better
position acquired a signal at 1753 EST, which was determined to
originate from a position 31 km northwest of Mackay (74 km south of
Whitehaven Beach). AusSAR reported that they did not have a high
level of confidence in the location identified, because contact
with the beacon signal was only maintained for approximately 100
seconds. AusSAR dispatched a search helicopter from Mackay however
the helicopter was not able to detect the signal. AusSAR was not
able to conclusively establish that the two distress beacon signals
identified in the Mackay area were associated with the activated
beacon at Whitehaven Beach.
The wind strength and sea state at the time of the occurrence
were not ideal for floatplane operations, particularly given the
pilot's relative lack of experience in open water operations. In
comparison, it was unlikely the non-standard floats contributed
significantly to the development of the accident. The loss of
directional control suggests a lower than ideal pitch attitude at
touchdown, a configuration which reduces a floatplane's directional
stability. The pilot's use of a distress beacon for search and
rescue purposes was appropriate, however the timeliness of his
rescue from the upturned aircraft can be attributed to the
effectiveness of the company's flight monitoring system and
subsequent search and rescue actions.
AusSAR further advised the following in relation to distress
beacon detection:
"The successful detection of a 121.5 MHz distress beacon by the
Cospas-Sarsat system is dependant on a number of factors involving
the beacon, the satellite, satellite pass geometry and the
receiving station (LUT). These factors include:
"a. the beacon performing in accordance with Australian/NZ
standards, particularly the beacon signal meeting approved
specifications;
"b. the beacon being deployed correctly i.e. line of sight to
the satellite is not obstructed, aerial is fully extended, battery
fully charged;
"c. the beacon operating long enough to reach normal operating
temperature, allowing the frequency to stabilise, before detection
(approx 10 mins);
"d. the satellite and LUT performing in accordance with
Cospas-Sarsat specifications;
"e. the satellite having an unencumbered view of the beacon and
the LUT;
"f. the LUT receiving a minimum of four minutes of data, which
includes the time the satellite was closest to the beacon;
"g. other strong transmissions in the bandwidth may mask the
beacon transmission; and
"h. a second satellite pass will be necessary to resolve the
ambiguity between the two positions calculated.
"Beacons operating outside the specifications may cause the
beacon not to be detected. Moreover, positional accuracy may be
affected or side bands may generate multiple detections, masking
the real beacon. Nevertheless, even if all the specifications
relating to the beacon, satellite and LUT are not met, the system
is designed so that 70% or more of the nominal solutions are
accurate to within 20 km of the real beacon position, and 95% are
accurate to within 40 km of the real beacon position. The
operational consequence of these accuracies is that further search
activity, typically homing by an aircraft, is required to ascertain
the precise position of the distress beacon and the nature of the
distress. This may take a number of hours, or might even need to
wait until light and weather are suitable for aircraft operations.
Pilots need to take account of these timescales when deciding what
survival equipment to carry."
AusSAR also advised that the current 121.5 MHz distress beacons
will become obsolete in February 2009 when the Cospas-Sarsat
satellite system will no longer process the signals. From that
time, only 406 MHz distress beacons will be detectable. A 406 MHz
beacon is more effective than a 121.5 MHz beacon under most
circumstances, because it allows near instantaneous detection by a
geostationary satellite, the digital signal includes a unique
identification code, the signal is more powerful, and beacon
detection is more accurate. Some 406 MHz beacons incorporate GPS
position (either integral or external feed) which further enhances
AusSAR's ability to accurately locate the beacon. The 406 MHz
beacon also requires correct deployment and functioning for optimum
performance.
Further information on operation of distress beacons can be
found in the Emergency Procedures section of En-Route Supplement
Australia (ERSA) or from the AusSAR website.