Everything You Need to Know about Emergency Locator Transmitters

Everything You Need to Know about Emergency Locator Transmitters

  • ELT (emergency locator transmitter). A self-contained radio transmitter that automatically begins transmitting on the emergency frequencies any time it is triggered by a severe impact parallel to the longitudinal axis of the aircraft.
  • Required by all U.S. civil airplane category aircraft except as provided below [91.207(e) and (f)].
  • Transmits on 121.5 MHz or the newer 406 MHz (highly recommended).
  • Batteries must be replaced after one hour of cumulative use or when 50 percent of their usable life has expired.
  • Expiration date for replacing (or recharging) the battery must be legibly marked on the outside of the transmitter and entered in the aircraft maintenance record.
  • Must be inspected every 12 calendar months.
  • Testing of an analog 121.5 ELT can only be done within the first five minutes after the hour, and you may transmit no more than three audible sweeps.
  • Digital 406 ELTs should only be tested in accordance with the manufacturer's instructions.
  • Airborne tests are not authorized for any ELT.

Operating without an ELT, a person may: [91.207(e)]

  • Ferry a newly acquired airplane from the place where possession of it was taken to a place where the ELT is to be installed; and
  • Ferry an airplane with an inoperative ELT from a place where repairs or replacements cannot be made to a place where they can be made.
  • No person other than required crewmembers may be carried aboard an airplane being ferried for the purpose of ELT installation or repairs.

Airplanes that do not require an ELT: [91.207(f)]

The ELT requirements of 91.207(a) do not apply to:

  • Aircraft while engaged in scheduled air carrier flights;
  • Aircraft while engaged in training operations conducted entirely within a 50 nm radius of the airport from which such local flight operations began;
  • Aircraft while engaged in flight operations incident to design and testing;
  • New aircraft while engaged in flight operations incident to their manufacture, preparation and delivery;
  • Aircraft while engaged in flight operations incident to the aerial application of chemicals and other substances for agricultural purposes;
  • Aircraft certified by the administrator for research and development purposes;
  • Aircraft while used for showing compliance with regulations, crew training, exhibition, air racing, or market surveys;
  • Aircraft equipped to carry not more than one person; and
  • An aircraft during any period for which the transmitter has been temporarily removed for inspection, repair, modification or replacement, subject to the following:

a. No person may operate the aircraft unless the aircraft records contain an entry that includes the date of initial removal, the make, model, serial number and reason for removing the transmitter, and a placard located in view of the pilot to show “ELT not installed.”

b. No person may operate the aircraft more than 90 days after the ELT is initially removed from the aircraft.

  • Aircraft with a maximum payload capacity of more than 18,000 pounds when used in air transportation.

ELT — 121.5 MHz is out; 406 MHz is in: (91.207, AIM 6-2-4, 6-3-2, P/C Glossary)

  • As of February 1, 2009, satellite- based monitoring of 121.5/243 MHz distress alerts is terminated. Cospas-Sarsat satellites now only monitor the new 406 MHz digital signal.
  • COSPAS is an acronym for the Russian words Cosmicheskaya Sistyema Poiska Avariynich Sudov, translation: "Space System for the Search of Vessels in Distress." SARSAT is an acronym for "Search and Rescue Satellite-Aided Tracking."
  • Currently, 121.5 transmissions are only monitored by ground-based facilities or overflying aircraft.
  • Pilots are encouraged to monitor 121.5 MHz and/or 243.0 MHz in flight to assist in identifying possible emergency ELT transmissions. However, it could take days before anyone detects a 121.5 signal, especially if the aircraft was not on a flight plan.
  • The unprotected 121.5 MHz frequency was never intended for space-based monitoring, so interference and false alerts were a huge problem. Newer 406 MHz models greatly reduce false alerts, and the coded data it broadcasts make it possible to contact with the owner directly via phone, which can resolve most false alerts.
  • Aircraft owners faced with replacing or installing a new ELT must decide whether to install a slightly cheaper (and very old, because no new ones are allowed to be manufactured) 121.5 MHz ELT or the slightly more expensive 406 MHz model. The choice seems obvious.
  • At this time, the FAA does not have any plans to require the installation of 406 MHz ELTs.
  • There are three basic varieties of the 406 ELT:

• 406 with an integral GPS;

• 406 capable of being fed position data by the aircraft’s GPS; or

• 406 without a GPS option

  • The 406 MHz frequency is also used by emergency position-indicating radio beacons (EPIRB) registered to maritime vessels. An EPIRB can be activated either manually or automatically when it comes in contact with water. Also using the 406 MHz frequency are personal locator beacons (PLB) that are manually activated and registered individually to a person. PLBs are used by hikers, hunters, explorers, off-road drivers, etc.

Advantages of the 406 MHz ELT:

  • More transmitter power (second, 5-watt bursts every 50 seconds).
  • Dedicated and protected frequency designed specifically for detection by satellites.
  • Near instantaneous satellite detection by geostationary satellites and polar-orbiting satellites in low orbit.
  • More accurate location calculations, resulting in a much smaller search area (1 to 3 miles).
  • Much faster search-and-rescue response.
  • Sounds like a winner!

Note: FAA regulations could change at any time. Please refer to current FARs to ensure you are legal.


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