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Audit of the collection of environmental data – Sleipner A

During the period 26-28 May 2010, the Petroleum Safety Authority Norway (PSA) performed an audit of environmental data collection on Sleipner A. The audit was performed in cooperation with the Norwegian Meteorological Institute (Met.no). No regulatory non-conformities were identified.


The background for the audit was that the quality of environmental data collection from Sleipner A is of great importance to the flying weather and flight control service at sea, weather-dependent operations in the activities, the supply service and also to the society at large as a foundation for Met.no’s national weather database.

To achieve a satisfactory degree of measurement accuracy, it is necessary to document that the available values’ accuracy is within regulatory requirements.

Goal
The purpose of the audit activity was to review relevant procedures for performing, maintaining and reporting the collection of environmental data, and assess the technical standard of systems and equipment on Sleipner A, pursuant to regulatory requirements in Section 25 of the Framework Regulations relating to requirements for collecting environmental data, Section 4b) of the Information Duty Regulations relating to requirements for retention period and discarding of data and Section 16 of the Facilities Regulations relating to instrumentation for monitoring and recording with guidelines and reference to NORSOK standard N-002. The regulatory requirements also include METAR (Meteorological Aerodrome Reports) observations.

Result
No regulatory non-conformities were identified. The measurement control did not uncover any variance from the recommended NORSOK N-002 standard for measurement results beyond tolerance between the operator’s measurement instruments and the control instruments and Met.no’s travelling standards.

Following the new requirements from the Norwegian Civil Aviation Authority, “2008-01-28 no. 81 ‘Regulations regarding flight weather service (BSL G 7-1)’” which came into effect on 1 January 2008, Statoil is required to update its weather station on Sleipner A to satisfy requirements for official METAR. For Sleipner A, this comprised placement and installation of infrared sea temperature gauges and was complete in May 2010. The equipment will be tested for a period going forward and the quality will be evaluated.

All meteorological equipment was subject to applicable control procedures for Sleipner A. Both the program for maintenance management and an overview of performed maintenance can be found in Statoil’s management systems and is traceable. The maintenance is performed by the technical personnel on board Sleipner A.

Observations
The PSA’s observations can generally be divided into three categories:

  1. Non-conformity: Related to observations where have identified breaches of the regulatory requirements
  2. Improvement item: Related to observations where we find deficiencies, but do not have sufficient information to be able to ascertain breaches of the regulatory requirements
  3. Conformity: Used for proven regulatory compliance

Conformities

Metadata
Reference is made to regulatory requirements stipulated in Section 25 of the Framework Regulations relating to requirements for collecting environmental data, Section 4b) of the Information Duty Regulations relating to requirements for retention period and discarding of data and Section 16 of the Facilities Regulations relating to instrumentation for monitoring and recording with guidelines and reference to NORSOK standard N-002 (“Collection of Meteocean Data”) item 4.2. The Metadata setup is in accordance with the recommended NORSOK standard N-002 (Annex 4).

Maintenance
Procedures for preventive maintenance of measurement instruments were reviewed. A detailed user guide has been developed for planning the preventive maintenance of all meteorological equipment. The scheme includes frequencies of maintenance to be performed daily, every 14 days, bi-annually and annually. Special feedback has also been provided to the system supplier concerning this maintenance scheme. The meteorological equipment was satisfactorily cleaned and in good order.
A fault in one of the control instruments in the radio room (TH1) was corrected, which meant that this also was checked during this audit.

Reference is made to regulatory requirements stipulated in Section 25 of the Framework Regulations relating to requirements for collecting environmental data, Section 4b) of the Information Duty Regulations relating to requirements for retention period and discarding of data and Section 16 of the Facilities Regulations relating to instrumentation for monitoring and recording with guidelines and reference to NORSOK standard N-002 (“Collection of Meteocean Data”) item 4.2, cf. Annex A, item 5.1.

Tolerance limits cf. NORSOK N-002 Annex A
Temperature (air): 0.20 °C
Temperature (sea): 0.20 °C
Relative humidity (rh): 5.00%
Air pressure: 0.30 hPa

Sensor exposure
The verification on board Sleipner A showed satisfactory exposure for all sensors in use. Ten series were performed of sensors TH2 and the control instrument, five series of TH1 and the control instrument and six series on pressure and the control instrument on Sleipner A (air temperature, air humidity and air pressure).

Sea temperature
Sensors are installed for sea temperature on Sleipner A (infrared sensors). The sensors were undergoing testing and could be replaced by sea temperature measurements from future supply vessels depending on the result of the testing.

Air temperature
Sensor TH1 for air temperature (placed in white instrument cabin on main deck) was checked against Met.no’s travelling standard Vaisala HMP233. Sensor TH1 was checked in seven series in the temperature interval 6.9-8.5 °C.

Mean deviation TH1 air temperature: 0.06 °C

Sensor TH2 for air temperature (placed in white instrument standard on main deck) was checked against Met.no’s travelling standard Vaisala HMP233. Sensor TH2 was checked in ten series in the temperature interval 6.9-8.5 °C. TH2 is used for display in the METAR report.

Mean deviation TH2 air temperature: 0.07 °C

The control sensor on Sleipner A for air temperature was checked against Met.no’s travelling standard Vaisala HMP233. The sensor was checked in three series in the temperature interval 6.9-8.5 °C.

Mean deviation control sensor air temperature: 0.07 °C.

Air pressure
Sensors for measuring air pressure were checked in six series in the interval 996.5-997.9 hPa against Met.no’s travelling standard of the type Digiquartz 765.

Mean deviation sensor 1: 0.09 hPa
Mean deviation sensor 2: 0.09 hPa
Mean deviation control sensor: The sensor was not checked because it is scheduled to be calibrated.

Air humidity
Sensor TH1 for air humidity (placed in white instrument cabin on main deck) was checked against Met.no’s travelling standard Vaisala HMP233. Sensor TH1 was checked in five series in the air humidity interval 61-79% rh.

Mean deviation TH1 air humidity: 1.4%

Sensor TH2 for air humidity (placed in white instrument cabin on main deck) was checked against Met.no’s travelling standard Vaisala HMP233. The sensor was checked in ten series in the air humidity interval 61-79% rh.

Mean deviation TH2 air humidity: 3.2 %

The Sleipner A control sensor for air humidity was checked against Met.no’s travelling standard Vaisala HMP233. The sensor was checked in the air humidity interval 82-86% rh.

Mean deviation control sensor for air humidity: 0.8%

Improvement items

No improvement items were identified in connection with the measurement results.

Sensors that were not checked

Wave measurement
The wave radar is placed in the south-east corner at the top of the living quarters. The wave radar measures over 180°, approx. from north through east to south. Miros is responsible for inspection and calibration of this equipment.

Ceilometer (cloud height gauge)
The ceilometer is placed by the helideck and was not physically inspected.

Wind gauge
The two ultrasonic wind gauges are of type Gill and were not physically inspected. These were placed at the top of the derrick, one at the north end, one at the south end. Both wind gauges are at the top of the derrick (the highest point on this part of the facility) and are considered to have adequate exposure.

Visibility sensor (PresentWeather sensor)
Two PW sensors were placed by the helideck and on the main deck, respectively, and were not physically inspected. The visibility sensor only measures visibility in a limited volume of air at the height it is placed. The placements are considered adequate.

Other comments

Conversations with the observer
METAR observations are sent from Sleipner A every half hour between 0700 and 1900 hours. The software for sending observations is MirPresMETAR, developed by Miros. Data display from the various meteorological sensors in the radio room was clearly laid out with suitable labelling of which data belonged to which sensors. The presentation of visibility and cloud base measurements was also adequate in Miros’ program.

Sleipner A has a SYNOP service.

Good observations on Sleipner A are very important to safety inter alia in connection with helicopter transport, weather-dependent operations on the facilities and for weather forecasts. The observer on duty during the audit is competent in sending METAR, but feels that SYNOP can be difficult sometimes. Cloud assessment takes the longest time to learn.

The observer was of the opinion that the cloud base measurements were a helpful tool in this work and that the annual refresher courses were valuable and necessary to stay technically competent. It was also mentioned that the refresher course was especially useful in that the participants could share experiences with other observers.

In accordance with the new regulations from the Norwegian Civil Aviation Authority, “2008-01-28 no. 81 ‘Regulations relating to flight weather service (BSL G 7-1)’”, which came into effect on 1 January 2008, the observers sending METAR shall undergo annual refresher courses in observation technique. The observer on board Sleipner A had completed the annual refresher course.
 

Øyvind Midttun, Press contact
Email: oyvind.midttun@ptil.no | +47 51 87 34 77