Helideck Monitoring System

The SMC Helideck Monitoring System is a module layout of the SMC Monitoring System designed with all the criteria of the current international code requirements for helideck operations in an offshore environment.

The SMChms provides motion and meteorological information in a clear and comprehensive graphical interface.

Helideck Monitoring System

Met-Ocean System

Together with SMC’s unique modular software solution that provides a flexibility of additional environmental instruments and custom displays. The display modules can be used by different operational teams with one server software solution.

Helideck Standards CAP437

The SMC Helideck Monitoring System is as flexible as many of today’s offshore vessels. Current industry requirements may require that a vessel works in various locations around the globe. Being able to meet all of the required Code and standards applicable in different regions is of critical importance.

The SMC HMS meets all of the following standards:

Display Access

Following the installation of the Helideck monitoring system software on a server PC a full software display is available using a standard Web browser User Interface format. Alternatively, a client software program is installed that can be used as a viewing option.

By standardizing on Web browser format, the SMChms software can be viewed across multiple platforms PC’s, Macs, Tablets, Smartphones and other PDU systems that are connected to the LAN/WAN that has permission to access the data. This reduces the need for additional software tools to be loaded onto multiple PC’s/Platforms.

Multiple remote connections are available across the network and the number of simultaneous connected users is unlimited and not restricted by separately purchase individual user licenses.

External Data Output

The SMChms software offers multiple options for output communications connecting to external systems supplying data from the Motion sensors and Weather instruments over for example SNMP, Modbus TCP/RTU and ASCII protocols.


Helimet is a shared weather information tool used by the offshore oil and gas industry in the UK. A configuration enables a standard Helimet transmission for the Offshore Helicopter Weather Network.

Voltage Free Contacts, Relays

With the installation of an optional Voltage Free Contacts card in the HMS server PC a dry voltage output signal can be generated for use to switch Helideck Lights and other alarm outputs.


A standard for HMS Systems usually requires but is not limited to the following motion and meteorological instruments. Motion, Wind, Air Pressure, Temperature and Humidity information, Cloud height and Visibility. Typically, the type of vessel and operational areas will determine the list of instruments required. Fixed installations, Semi Submersibles, crane and lay barges, FSU’s, large ships, drill ships, FPSO’s and jack up rigs all are required to have the full list of instruments.

Smaller vessels and vessels with less frequent helicopter operations such as DSV’s, support and seismic vessels along with tankers and super yachts require only Motion, Wind, Air Pressure, Temperature and Dew point information.

Motion Sensors

Current guidelines for the CAP437 as described in the HCA HMS v9 specification requires a Roll & Pitch accuracy of better than ±0.1°RMS over 0 – 3.5° and a Heave Rate of better than ±0.1 m/s RMS over a range of 0 to 1.3 m/s. Additionally with the new MSI Helideck Accelerations better than ±0.01 m/s² RMS in the range of 0 – 0.2 m/s² are required.

Inclination and Significant Heave Rate (SHR) are calculated within the HMS software along with the MSI Motion Severity Index.

Wind Speed and Direction

Dependent on the standard and requirements typically an instrument should be accurate to ±1kn (0.51m/s), or ±10% for wind speeds in excess of 10kn (5.1m/s) across an operating range from 0 – 100kn (0 – 51m/s). And for direction with wind speeds over 2kn (1m/s) the accuracy should be better than ±10%.

As an extra note in installations where the primary anemometer is obstructed by a vessel structure a second unit should be added at a separate location to cover any angles obstructed by the first.

Relative wind direction (RWD) and Wind Severity Index (WSI) are calculated with the HMS Software.

Air Temperature and Humidity

Dependent on the standard and requirements typically an instrument with ±1.0°C for air temperature and dew point over a Temperature range of -25°C to +50° and Humidity of 5 – 100% relative humidity condensing.

Any instruments should be exposed in an instrument housing radiation shield or Stevenson screen as close to the helideck as possible away from exhausts or building heating.

Barometric Pressure

Typically depending on the standard two co-located pressure sensors that are accurate to within 0.5 Hectopascal of each other with a ±0.5 Hectopascal minimum accuracy should be used. These should have an intolerance range of 900 – 1050hPa.

QNH and QFE data is set up within the HMS software.

Visibility and Present Weather

Visibility distances of up to 10km should be displayed along with a selection of present weather phenomena that are detailed in CAP437 E7 & CAP 746 (Chapter 4) need to be reported. Examples such as Thunderstorms, Rain and type, Snow and Ice along with Fog.

Cloud Height

Cloud is to be reported as laid out in CAP437 E.9 & CAP 746 (Chapter 4), examples would be: FEW, SCT, BKN, OVC along with additional cloud type and heights up to 5000ft unless Cumulonimbus (CB) or Towering Cumulus (TCU) clouds are present.

Wave Height

If a wave height sensor has been installed measurements of significant wave height should be displayed.


A vessels heading is required to show Magnetic North and corresponding compass directions. A Compass display showing vessel heading as well as being used to calculate the True Wind data.


Vessel Position data is displayed within the HMS software and is also recorded for Pre-Flight reports and Data logging. The GPS position data is also used to calculate True Wind Data.