Sea Search Operations AF 447 A February 2010

Transcription

1 Sea Search Operations AF 447 A February 2010

2 Search Phases Phase 1 : Acoustic search for Underwater Locator Beacons (10 June to 10 July in the search zone) Phase 2 : Search for the wreckage using a towed array SONAR (27 July to 17 August in the search zone) Preparations for Phase 3: Establishment of international group (AAIB, BFU, CENIPA, MAK, NTSB, SG Mer, US Navy) Determination of the search zone International call for tenders and selection of means

3 Determination of the Search Zone

4 A Scientific Challenge The sea area is turbulent, the currents are rapidly variable, which makes it difficult to generate models, Oceanic general circulation models in operational mode do not reproduce the available current observations (phases 1&2), It is necessary to have additional current measurements to overcome this problem, Time management in relation to the operational constraints.

5 Un enjeu scientifique La zone est turbulente, les courants rapidement variables, ce qui rend leur modélisation délicate, les modèles de la circulation générale océanique dans leur mode opérationnel ne reproduisent pas les observations de courant disponibles (phases 1&2), il est nécessaire de disposer de mesures de courant supplémentaires pour dépasser cette situation, gestion du temps en fonction des contraintes opérationnelles.

6 Constitution of the Group Objective: broaden the range of skills available. Call for international cooperation Calling on additional expertise in the fields of: Collection and analysis of data, Re-analyzing meteorological data, Re-analyzing (and re-processing) oceanographic data, Theoretical research, Statistics.

7 Group Members Société Collecte Localisation Satellites (France), Ecole Normale Supérieure (France), Laboratoire de Physique des Océans / IFREMER (France), Laboratoire de Physique des Océans / CNRS (France), Institut de Mathématiques de Toulouse (France), Institute of Numerical Mathematics of the Russian Academy of Sciences (Russian Federation), Mercator Océan (France), Météo-France (France), National Oceanography Center (United Kingdom), Service Hydrographique et Océanographique de la Marine (France), Woods Hole Oceanographic Institution (United States).

8 Group Tasks Widen collection and analysis of data Improve estimation of currents Estimate errors in drift calculations Propose a search zone

9 Widen collection and analysis of data Observations of currents, 5 different wind models, Data relating to the debris (initial information on 5 June), Sattellite data (temperature, colour of water, water height anomaly de), etc.

10 Improve Estimation of Currents Complementary approaches: a posteriori validation of data and implementation of refined models, assimilation of observations on the currents, methods to interpolate observations. Examples of results

11 Estimated currents on 5 June at 18h by the optimal interpolation method

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13 Estimate Errors in Drift Calculations Estimation of the models capacity to recreate the trajectories: - tests on trajectories of buoys, - modelling of the debris dispersion, Sensitivity of the models results to forcing by the wind, Sensitivity to the initial conditions, Uncertainty of the effect of the wind on the submerged parts of the debris, Uncertainty of the correlation scales, Influence of the waves, «Robustness» of the estimates.

14 Propose a Search Zone Statistical model for the integration of the results Weighting of the results according to the associated error Theoretical confidence interval of 95%

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16 Limitations The group s work was based on: the state of the art in oceanography, a review of the results and methods by recognized experts,..though this work reached the limits of current knowledge. Optimisation and revision of the zone during the sea operations.

17 Means Selected

18 Means Selected for the 3 rd Phase Two search vessels: Anne Candies (Phoenix International, United States) Seabed Worker (Seabed Group, Norway)

19 Equipment on Board the Seabed Worker Three autonomous underwater vehicles (AUV) Three REMUS 6000 (WHOI & GEOMAR) Side Scan Sonar 120/410 khz One ROV (SEABED) Triton XLX 4000

20 Means on Board the Anne Candies Deep Towed Sonar and ROV managed by the US Navy ORION (56 / 240 khz) CURV 21 (6,000 metres)

21 Additional Means Equipment Speed Turn time Seabed type Autonomy Ship requirements Area coverage Deep Towed SONAR 2 kt 3h Relatively smooth, slight slopes 10 days Consistent slow speed 100 km 2 per day AUV 2 to 4 kt 1/4h Relatively smooth, medium slopes 1 to 2 days with PAC Escort 200 km 2 per day w/ 2 AUV s ROV 0.5 to 1 kt 1/4h All 3 days Dynamic positioning 5 km 2 per day

22 Examples of SONAR Data Rough terrain Sedimentary zone

23 Example of a Detection (phase 2) To be compared with other accidents to aircraft of a similar size

24 Example: B-52 Guam Accident (July 2008) ORION 56 khz 900 m scale

25 Results double-checking doubtful data - the Victor ROV => cluster of rocks

26 Mobilizing the Means Equipment from US Navy + three REMUS 6000 (Woods Hole & Washington) In the zone 3 days later Transfer of equipment on board the Seabed Worker Arrival of specialized teams and investigators Mid-March 2010

27 On-board Team Under the direction of the BEA: specialists from the manufacturer, the airline, foreign counterparts (AAIB, BFU) and from IFREMER. Presence on board of two senior police officers and a liaison officer from the French Navy

28 Additional Logistical Elements Stationing of a French Navy patrol ship at Cayenne for possible recorder transport By plane Transfer Cayenne Site

29 Conclusions Means selected: Working to a depth of 6,000 m Complementary (ROV, AUV, towed array sonar) Fail-safe back-ups: Two ships Three autonomous SONARS + 1 deep towed SONAR Two ROV s

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