How Transmitters Keep Aircraft Safe in Emergencies

Modern aviation is incredibly advanced, and most aircraft today are full of technological wonders. Auto-pilot guidance systems and meters and gauges of all shapes and sizes help protect planes in the sky and on the ground. Additionally, digital connectivity plays a big role in keeping aircraft connected to GPS satellites and Internet communication systems.

Today’s airplanes and other flying machines also use a number of components that detect changes in position and orientation, allowing circuits to be opened and closed by pushing a button or flipping a toggle. Although aviation professionals and enthusiasts can point to a number of electronic gizmos as being essential, emergency transmitters are possibly the most important safety components in plane crash emergencies.

What Is An Emergency Transmitter?

An emergency transmitter is a device that can be used to send a signal in the event of a plane crash emergency. Unlike traditional radio communications, emergency transmitters are self-activated when certain conditions are achieved. One condition that can activate an emergency transmitter is a sudden impact, but the cabin crew of an aircraft can also trigger an alert manually if an emergency occurs.

Most emergency transmitters use broadcast frequencies of 121.5 MHz and 243 MHz. When a transmission is sent out, GPS technology may calculate the general location of the aircraft broadcasting the signal, but search crews must track the emergency signal as they close in on the suspected location. This allows emergency response personnel to locate the aircraft in the event of a crash. Additionally, this is why most emergency transmitters are referred to as ELTs, or emergency locator transmitters.

Is A Transmitter The Same As A Transponder?

Although the two sound similar, a transmitter and a transponder are two different types of devices. A transmitter is used to send or transmit information. A transponder is a device that receives messages, but it is coupled with a transmitter that automatically sends a response when a message is received. The transponder itself does not send a signal, but instead, it passes a message on to the transmitter.

You may also hear about transceivers. These are devices that are designed to both send and receive messages. Aircraft may be equipped with all three types of devices, but an ELT is the one primarily used to automatically send a distress signal in the event of an accident.

How Are ELTs Mounted?

ELTs are usually mounted on small aircraft along with an antenna. The internal components of the ELT system are kept inside the aircraft, and they rely on the antenna to send the signal in the event of a crash. For a time, satellites were used to receive signals from ELTs, but this has since changed. Today, signals broadcast from ELTs are sent still sent via satellite when older technology is in use, but modern ELTs send signals via VHF radio.

How Are ELTs Powered?

Because a plane crash or emergency landing may result in the loss of power to an aircraft, an ELT must have a separate power source to draw from in order to continuously broadcast its signal. Most ELTs are powered by batteries to perform for at least 24 hours after a signal broadcast has been initiated. Since these devices operate by creating a homing signal, they need to be able to consistently perform while search and rescue operations are underway. Depending on conditions in the area of a crash or emergency landing, it may take rescuers hours or days to locate the source of the distress signal.

Are False Alerts A Problem?

The issue of false alerts is something aviation professionals take very seriously. Because a false alert can trigger a massive search and rescue operation, everything possible must be done to ensure that ELTs only begin transmitting in the event of an actual emergency. False alerts are part of the reason why satellite communication is no longer the preferred method for receiving ELT signals. Modern systems employ rigorous testing standards, and pilots must also pass testing and certification in order to use ELTs in the aircraft they fly.

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