Laser Airborne Depth Sounder
|Commanding Officer||Lieutenant Commander Richard Mortimer|
|Aircraft||de Havilland Dash 8 - 200|
|Crew||2 pilots (civilian), 2 survey systems operators (Navy)|
|Aircraft take off weight||18 tonnes|
|Aircraft transit speed||300 knots|
|Survey speed||140 to 200 knots (72 to 103 metres per second)|
|Operating height||366 to 670 metres above the sea surface (1200 to 1600 feet)|
|Survey Measurement Range||
|Sounding pattern||47 to 288 metres wide|
|Navigation||Wide Area Global Positioning System|
|Sortie duration||up to 7 hours|
|Personnel (Contract)||supported by Fugro LADS Corporation with 4 onsite contractors|
|Home Base||Cairns, however the entire Flight is deployable and has been based out of Mackay, Darwin and Broome for up to 10 weeks.|
The RAN Hydrographic Service, in addition to the six survey ships, also employs an extremely capable and effective airborne unit. The Navy's Laser Airborne Depth Sounder (LADS) Flight was formed in 1992 after more than 20 years of research and development. The first LADS aircraft used was built in 1976 and previously operated by East West airlines. It was the last operational F27 in Australia and had been extensively modified to incorporate bay doors under the fuselage, additional fuel tanks, precise navigation systems, and a stabilised platform for the laser. The Fokker was replaced in November 2009 with the de Havilland Dash 8 – 200. The Dash 8 had previously been used by Fugro LADS Corp (formally Tenix LADS Corp) conducting similar survey activities internationally. The Australian Navy was the first and remains one of only a few military organisations in the world to employ this survey technique.
The heart of the survey system is a powerful laser that transmits both infrared and visible green beams from under the aircraft. The fixed infrared beam provides height information above the sea surface whilst the green beam produces a scan width of up to 288 metres recording depths up to 70 metres deep in pristine waters and heights of up to 50 metres.
Navy personnel at LADS fly in teams of two and operate the laser survey system from the main cabin of the aircraft. Back on the ground the depth data is processed and then sent to the Australian Hydrographic Office in Wollongong to become nautical charts. During survey operations the LADS aircraft flies at between 366 and 670 metres altitude and surveys up to 40 square nautical miles per day at 100% coverage. With more than 7 hours endurance and flying five days per week, the LADS aircraft totals up to 140 sorties annually.
The LADS Flight is based at Cairns airport in Far North Queensland however the entire unit can be deployed for up to 3 months. In recent years these deployments have included Mackay, Darwin and Broome. The LADS survey team consists of seven RAN Hydrographic specialists: two officers, two senior sailors and three junior sailors. Specialist support is provided under contract by Fugro LADS Corporation and includes pilots, aircraft engineers, systems technicians and a field manager. Together, the Navy and civilian personnel form a highly specialised team ensuring the RAN remains at the forefront of surveying capability.
A number of areas are normally surveyed concurrently by the LADS Unit, and the aircraft can be diverted from one to another if localised weather conditions or water clarity prove unsuitable. While the pilots are responsible for flying the aircraft and for navigation while on transit, once approaching the survey area the Navy survey operators take charge. From then until departure for base these operators are responsible for selection of survey runs, directing the pilots onto each line and directing the aircraft from one area to the next. They also control the laser's tuning and receiver gain settings and monitor system performance.
In relatively clear coastal waters LADS has proved to be highly effective. Its productivity and area coverage are so good that surface units are no longer routinely tasked in these areas. In regions of poor water clarity LADS is a complementary capability to surface survey units. The technology offers an awe inspiring place to work and, more than 20 years after the first experimental laser flew, this Australian designed system remains at the forefront of both laser based systems and hydrographic survey systems in general. While relatively unknown, it is a highly effective Navy asset.
For further information on LADS, visit the Australian Hydrographic Service (external link) website.