Sea Search Operations

AF 447 – A330-203

17 February 2010

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

Determination of the SearchZone

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.

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.

• 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.

Constitution of the Group

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).

Group Tasks

• Widen collection and analysis of data

• Improve estimation of currents

• Estimate errors in drift calculations

• Propose a search zone

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.

Improve Estimation of Currents

Complementary approaches:

• a posteriori validation of data and implementation of refinedmodels,

• assimilation of observations on the currents,• methods to interpolate observations.

Examples of results

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

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.

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%

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.

Means Selected

Two search vessels:

Anne Candies (Phoenix International, United States)

Seabed Worker (Seabed Group, Norway)

Means Selected for the 3rd Phase

Equipment on Board the Seabed Worker• Three autonomous underwater vehicles (AUV)

– Three REMUS 6000 (WHOI & GEOMAR)

• One ROV (SEABED)– Triton XLX 4000

Side Scan Sonar 120/410 kHz

Means on Board the Anne Candies

• Deep Towed Sonar and ROV managed by the US Navy

CURV 21 (6,000 metres)ORION (56 / 240 kHz)

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 km2

per day

AUV 2 to 4 kt 1/4h Relatively smooth, medium slopes

1 to 2 days with PAC

Escort 200 km2

per day w/ 2 AUV’s

ROV 0.5 to 1 kt 1/4h All 3 days Dynamic positioning

5 km2

per day

Additional Means

Examples of SONAR Data

Sedimentary zoneRough terrain

Example of a Detection (phase 2)

To be compared with other accidents to aircraft of a similar size

Example: B-52 Guam Accident (July 2008)

ORION 56 kHz –900 m scale

…double-checking doubtful data - the Victor ROV

=> cluster of rocks

Results

Mobilizing the Means

Mid-March 2010

Equipment from US Navy + three REMUS 6000

(Woods Hole & Washington)

In the zone3 days later

• Transfer of equipment on board the Seabed Worker• Arrival of specialized teams and investigators

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

Additional Logistical Elements

• Stationing of a French Navy patrol ship atCayenne for possible recorder transport

CayenneSite

Transfer

By plane

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