Methods and instruments

Methods

When undertaking its observation missions, the aircraft makes various flights between clearly defined waypoints and may deviate from these depending on operational circumstances.

B1, B2, FB1, UKB, NH, etc. are the waypoints used to plan flights. The black line delimits the Belgian maritime area (including territorial waters and the Exclusive Economic Zone)

During routine flights, the aircraft scans the sea surface with its two lateral antennas searching for surface pollution. This specific radar is a SLAR -Side Looking Airborne Radar- enabling, thanks to its emitted microwaves, to visualise a stroke of 20 kilometres on either side of its route.

As soon as pollution is suspected, the aircraft is directed towards the position. Photographs are taken and the scene is recorded on video using a laterally or vertically positioned video camera as well as infrared and ultraviolet sensors.

If a case of oil pollution is confirmed, the oil volume on the surface of the water is estimated by the operator.

This estimation of the volume of oil discharged makes it possible to evaluate the impact such a pollution will have on the marine ecosystem.

After a clear positioning of the spill onto an electronic chart, the operator assesses the total extent of the area affected by the pollution and the percentage of oil cover in this total area with the support of reference tables. This enables him/her to get an estimate of the surface of the area covered by oil.

After this, in order to assess the volume of oil, the thickness is estimated, making use of the Bonn Agreement Oil Appearance Code (BAOAC, 2004). It is used by all the countries which have signed the Bonn Agreement .

The code takes into account the typical visual appearances an oil slick may have, each of which corresponds to a category of thickness of the oil spill.

The categories include a minimum and a maximum value. The minimum volume values calculated are used in statistical matter and legal actions. The maximum volume values being used for cali bration of the pollution combating means.

Each appearance corresponds to a thickness of the layer of hydrocarbons on the surface of the water

1.Observation

2. Assessment of the total extent of the area affected

3. Assessment of the percentage of oil cover with reference tables

4. Assessment of the thickness with the BAOAC appearance code

An oil slick with distinct appearances

When a vessel is caught in the act, the aircraft undertakes an approach manoeuvre in order to identify the polluter. The action involves positioning the aircraft at a sufficient distance from the vessel, during the day as well as at night, in order to be able to read the name and home port written on its hull.

Manoeuvre to approach a vessel in order to identify it. Adapted from Source: Oil pollution at sea, Securing evidence on discharges from ships. Manual, Bonn Agreement, 1993

Identifying a vessel (in this case not a polluting ship)

A vessel dumping waste

Unfortunately, the polluter is often already far away… But once an operator has been able to observe an infringement, an official statement of the facts has to be drawn up very quickly. MUMM has an image-processing unit that can be used to add visual elements to the written report.

This document is then sent to the competent Belgian public prosecutor's office, which will forward it to the flag state concerned, as appropriate. The proceedings vary depending on the location of the infringement, the nationality of the vessel and its next port of call.

Instruments

1. SLAR - Side Looking Airborne Radar

This black 'tube' contains one of the two lateral antennae of the SLAR. A black 'vein', a zone without radar echo, indicates the probable presence of a discharge of oil from a vessel

The principle of this airborne remote detection system is based on the smoothing effect of oily substances on the waves. Pollution consisting of substances other than oil has to be detected visually.

2. Ultraviolet images are used to detect the thinnest areas of the slick and hence determine the precise extent of the pollution.

3. Infrared image provides additional information about the thickness of the pollution by identifying the differences in temperature between the oil and the surrounding sea water. De localisation of the thickest parts of the pollution is essential for the support to the pollution fighting units.

4. The analogical video camera is used to record all the observations. It can be positioned laterally or vertically.

5. Information from the first four sensors is collected and displayed on the central console and annotated using data from navigation instruments: GPS providing details of the date, time, position, direction and speed, as well as radar altimeter specifying the altitude. The console combines all the monitoring and image processing elements as well as means of telecommunication such as the VHF Marine and the intercom used to maintain constant dialogue with the pilots and take note of external elements (air traffic, control tower, etc.)

The instrument control console aboard the aircraft

Three pictures of the same observation via three sensors; from the left to the right: video, infrared, ultraviolet

6. An electronic chart in a laptop computer linked to the GPS system can establish a precise position in our maritime area. In addition to useful basic data (tides table, manuals, etc.), the computer also contains the reference documents needed to undertake all these missions.

7. A digital photographic camera is used to take pictures, enabling a real exchange with the authorities to provide a clear idea of the reality of the situation or to capture a specific moment in time.

8. The operators make available to the authorities and to research specialists the knowledge accumulated within the Management Unit over the past years, and in particular the observations they have made with their own eyes. Human observation is still an important element in the quality of the data collected and supplied to the various players.

 Results

 Legal actions