EPIRB & PLB: THE COMPLETE INFORMATION GUIDE

 What is an EPIRB and How Does it Work

An EPIRB, or Emergency Position Indicating Radio Beacon, is a beacon equipped with a satellite transmitter that sends an emergency signal and location information to a constellation of satellites specifically designed to receive and identify these signals. The coverage is global, meaning satellites can detect an active EPIRB signal anywhere on the planet.

EPIRBs transmit a "distress" signal on the 406 MHz frequency, monitored by the COSPAS/SARSAT satellite system. The signal is digital and includes a unique identifier (Hex ID) for the vessel transmitting it. Modern EPIRBs also transmit on the 121.5 MHz frequency, though at a reduced power, as an additional tracking signal for rescue units like Coast Guard boats or SAR helicopters.

COSPAS/SARSAT operators can detect the emergency signal and identify the sender. EPIRBs must transmit continuously for at least 48 hours to meet certification standards.

Key Points:

• EPIRBs transmit on 406 MHz and 121.5 MHz (limited power).
•  They send a coded signal identifying the vessel.
•  The signal is detectable anywhere in the world.

 Types of EPIRBs: Category 1 and Category 2

The activation of this device can be either automatic or manual. However, almost all EPIRBs are capable of automatically activating upon contact with water.

All models of ACR Electronics EPIRBs are equipped with contacts and an activation circuit that allows the beacon to activate upon contact with water. Other EPIRBs on the market are not necessarily equipped with this system and are therefore completely manual.

> Category 1 (Cat. I) EPIRB: An EPIRB is classified as "Category 1" (Cat. I) if it is placed inside a special container with a hydrostatic release mechanism that releases the beacon only in the event of sinking to a depth of about 4 meters.

 Due to their automatic activation feature, Category 1 EPIRBs must be installed externally. See EPIRBs in the shop >>

> Category 2 (Cat. II) EPIRB: Category 2 EPIRBs are not enclosed in a special container like Category 1 but are mounted on a support with a manual quickrelease mechanism. In the event of sinking, the EPIRB will not detach on its own because Category 2 does not have a hydrostatic release.

 The EPIRB will not activate—even if equipped with wateractivation contacts—as long as it remains in its support, the activation circuit remains inhibited. In an emergency, the Category 2 EPIRB must be manually released from its support and placed in water. In this case, it will activate immediately.

 Various manual activation switches and buttons are therefore only secondary commands for EPIRBs equipped with a wateractivation circuit. EPIRBs without this feature must always be manually activated using the appropriate switch or button. See EPIRBs in the shop >>

In summary:

Category 1 (Cat. I) EPIRB: These devices are housed in a container with a hydrostatic release. In the event of sinking, the container opens, expelling the EPIRB, which surfaces and transmits the signal. All Category 1 EPIRBs activate upon contact with water and must be installed externally.

EPIRB Category 2 (Cat. II):  These devices are mounted on a bracket and can only be released manually. Not all Cat. II EPIRBs have an automatic water-activation system. Some must be manually released and activated before being placed in water. It is advisable not to install them directly outside but in an enclosed and protected environment, provided it is easily accessible.

 Other Distinctions: Class 1 and Class 2

Many customers have asked about the distinction between "Class 1" or "Class 2" marked on their EPIRBs. This distinction has nothing to do with the aforementioned Category 1 or Category 2. This additional distinction should not cause confusion.

The references to Class 1 or Class 2 exclusively identify the type of battery installed inside the EPIRB and are distinctions dictated solely by regulations in the field of logistics and air transport (IATA directives).

Since we are talking about lithium batteries, to prevent potential fire hazards that could be particularly dangerous aboard commercial aircraft, a specific classification for this type of battery has been introduced.

Older generation batteries, with a higher lithium content, are classified as Class 1.

Newer generation batteries are classified as Class 2, as they are composed of several distinct cells with a significantly limited amount of lithium. EPIRBs labeled as "Class 1" cannot be shipped on commercial flights. There are no such limitations for Class 2 batteries, but a technical sheet will be required at the time of shipment.

How Personal Locator Beacons (PLBs) Work

Personal Locator Beacons (PLBs) are personal safety devices designed to send distress signals in emergency situations, anywhere in the world. These devices use satellite technology to communicate with search and rescue services and are widely used in outdoor activities such as hiking, boating, aviation, and other remote areas.

Activation and Signal

PLBs are manually activated by the user in an emergency, usually by extending an antenna and pressing a power button. Once activated, the PLB transmits a distress signal on the international frequency 406 MHz, used by the COSPAS-SARSAT satellite system. This signal contains a unique identifier that allows emergency services to identify the device and its owner.

Location

Most PLBs have a built-in GPS receiver, which determines the precise coordinates of the device's location. These coordinates are included in the distress signal, allowing for rapid and accurate location by rescuers. In addition to the main frequency of 406 MHz, PLBs also transmit on a homing frequency of 121.5 MHz. This low-power signal is used by air and ground search teams to accurately locate the device once it is in the vicinity.

Many PLBs are equipped with a strobe lamp that emits bright flashes, which improve the visibility of the device, especially in low-light conditions or during night-time search operations.

Registration and Programming

Before use, PLBs must be registered with the relevant authorities in your country. Registration includes personal information and emergency contact details, which are essential for rescue services. Programming the device is done to assign a unique identification code.

Battery and Maintenance

PLBs are powered by lithium batteries, designed to ensure continuous transmission for at least 24 hours once activated. These batteries have a long shelf life, usually up to 5-7 years, and must be replaced upon expiration or after use. PLBs are designed to be robust and resistant to extreme environmental conditions, in fact user-side maintenance is minimal, mainly limited to periodic self-diagnosis tests to ensure the correct functioning of the device. It is essential to replace the battery according to the manufacturer's instructions to ensure that the device is always ready for use.

In summary:

• PLBs transmit simultaneously on 406 MHz and 121.5 MHz (with limited power).

• PLBs transmit a coded signal that is directly traceable to the person, regardless of their location or activity (outdoor, fishing, flying...)

• The signal emitted by the PLB is detectable in any part of the globe.
  
  

EPIRB vs PLB Comparison

A common question from customers is whether it is possible to replace an EPIRB with a PLB, considering that both transmit on the same frequency and are picked up by the COSPAS/SARSAT system.

Although PLBs are less expensive and require easier maintenance than EPIRBs, the answer is no: a PLB cannot replace an EPIRB in situations where the latter is required by law. Vessels that must have an EPIRB on board, such as those for unlimited navigation or fishing vessels, are not compliant if they replace the EPIRB with a PLB.

However, the PLB can be a great addition to personal safety, being worn on the body while the EPIRB remains tied to the vessel.

Key Differences

Size and Battery

EPIRB: Larger, with a battery life of 48 hours.

PLB: Smaller, with a battery life of 24 hours.

Activation

EPIRB: Can be activated automatically in the event of sinking.

PLB: Must be activated manually by extending the antenna and pressing a button.

Usage

EPIRB: Mandatory on some vessels, ideal for serious maritime emergencies.

PLB: Not mandatory, but useful for personal safety in outdoor activities, easy to carry due to its small size.

In summary, while the EPIRB is essential for compliance with maritime regulations and vessel safety, the PLB offers an additional and versatile option for personal safety at sea and in many other outdoor activities.