What are the types of aircraft ELTs?

Aircraft Emergency Locator Transmitters are carried aboard most general aviation aircraft in the U.S. and are designed to transmit a distress signal on 121.5 and 243.0 MHz frequencies. The family of ELTs is divided by mounting style and by the radio technology they employ. Automatic fixed (AF) units are permanently attached to an aircraft and are normally installed in the tail, whereas automatic portable (AP) models can be installed in the cabin. In terms of signaling technology, 121.5 MHz and 243.0 MHz ELTs are analog devices, while 406 MHz ELTs are digital transmitters that can be encoded with the owner's contact information or aircraft data; these digital units include a low-power 121.5 MHz homing transmitter to aid searchers in the terminal search phase and can provide Search and Rescue personnel with aircraft location, within 100 meters, in less than a minute. Homebuilts other than airplanes - helicopters, gyroplanes, balloons, gliders, airships, trikes, and powered parachutes - do not require an ELT under regulation.

What are the types of aircraft ELTs?

The types of aircraft ELTs are detailed below.

• Automatic Fixed (ELT-AF): ELT-AF devices are permanently attached to the aircraft and designed to stay attached even after a crash to aid Search and Rescue (SAR) teams in locating a crash site.
• Automatic Portable (ELT-AP): While attached to an aircraft, ELT-AP devices can be removed from the aircraft and continue to function. These devices act as an ELT-AF and can be activated by a crash, but can also be removed and tethered to a liferaft or person, or carried to a safe location away from the crash site. This type of device is designed to bring SAR teams to the survivors rather than the wreckage.
• Survival (ELT-S): ELT-S type devices are portable in nature, are manually activated, and are the type typically carried by backpackers or liferafts.
• Automatic Deployable (ELT-AD): ELT-AD devices are designed to be attached to an aircraft, but deploy automatically after a crash event has been detected. ELT-AD devices must be capable of floating on water and are designed to help crash investigators locate the crash site.
• Distress Triggered (ELT-DT): ELT-DT devices are designed to be activated by the aircrew, or automatically by an internal or external trigger. In-flight events and detection criteria are defined in European Organization for Civil Aviation Equipment (EUROCAE) Specification ED-237, MASPS for Criteria to Detect In-Flight Aircraft Distress Events to Trigger Transmission of Flight Information.

All types of ELTs operate on one of three frequencies - 121.5 MHz, 243.0 MHz, or 406 MHz. Analog 121.5 MHz and 243.0 MHz ELTs emit a distinctive downward-swept audio tone, whereas 406 MHz ELTs are digital transmitters that send a unique digital signal directly linked to the aircraft and its owner. The COSPAS-SARSAT satellite system decodes the 406 MHz code and delivers data to the appropriate search-and-rescue center, while the embedded low-power 121.5 MHz homing transmitter guides nearby search aircraft. Regulation 14 CFR 91.207 requires that an approved personal or automatic type emergency locator transmitter be attached to the airplane, guaranteeing that whichever form is chosen - fixed, portable, or deployable - the ELT antenna remains positioned to radiate the distress signal effectively after activation.

Is an ELT required on an experimental aircraft?

Yes, an ELT is required on an experimental aircraft. The 14 CFR 91.207 rule applies to experimental category aircraft the same way it applies to standard category aircraft. Single-seat airplanes are exempt from the requirement for an ELT. If the experimental aircraft has more than one seat, it is required that an ELT be included.

What is the best ELT for an experimental aircraft?

The best ELT for an experimental aircraft is the ARTEX ELT 345. The ARTEX ELT 345 is the fastest-selling unit on the market and the lightest, smallest-form-factor TSO-approved beacon designed for experimental and light-sport fleets. It transmits on 406 MHz and 121.5 MHz, locks position within three minutes when the built-in GPS interface is connected, and ships with either a 15-in or 23-in whip antenna plus a two-wire slim-line remote switch.

Cost is USD 874.95 for the standard kit and USD 387.50 for the six-year Artex ELT110-4 replacement battery, an industry-low price for a 406 MHz beacon that still meets the quality standards of the ARTEX brand. Owners report that the 345 installs quickly in composite or tube-and-fabric airframes, activates automatically on 6-axis crash sensing, and can be tested or manually triggered from the three-position cockpit switch.I deem the ARTEX ELT 345 as an excellent choice due to its interconnected GPS. Since it can be tracked by the COSPAR-CARSAT module, it gives a firm degree of protection.

Jim Goodrich

Pilot, Airplane Broker and Founder of Tsunami Air

Expert behind this article

Jim Goodrich

Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.