CAP Talk

Operations => Emergency Services & Operations => Topic started by: rescue520 on November 27, 2009, 08:15:29 AM

Title: ELT STANDARDS
Post by: rescue520 on November 27, 2009, 08:15:29 AM
G'Day all
I was just wondering if anyone knew where i could find the Standards for ELT's?
Not after the carriage requirements but more specifically
Frequencys requriements - 406 121.6 243 etc
Min operating time
cold shock requirement etc.
I have all the information on PLB's & EPIRBS but unable to find the ELT
Thanks for your help in advance
Rescue
Title: Re: ELT STANDARDS
Post by: N Harmon on November 27, 2009, 02:10:25 PM
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/e2b1e589c98200f886256dc900695b8c/$FILE/C91a.pdf

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/0F451B230D34559F86256DAC0068F32A?OpenDocument

Also, here is some good information about the signal properties of 406mhz:

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=78313
Title: Re: ELT STANDARDS
Post by: Airrace on November 27, 2009, 05:22:02 PM
ELTs are emergency transmitters that are carried aboard most general aviation aircraft in the U.S. In the event of an aircraft accident, these devices are designed to transmit a distress signal on 121.5, 243.0-megahertz frequencies (and for newer ELTs, on 406 MHz). Currently, ELTs are required to be installed in almost all U.S.-registered civil aircraft, including general aviation aircraft, as a result of a congressional mandate. The mandate resulted from the 1972 loss of U.S. Representative Hale Boggs and Nick Begich in Alaska after their aircraft crashed and was never found.

When ELTs were mandated in 1973, most GA aircraft were equipped with an ELT that transmits on the 121.5 MHz frequency, the designated international distress frequency. The original ELTs were manufactured to the specifications of an FAA technical standard order (TSO-C91) and have an activation rate of less than 25 percent in actual crashes and a 97 percent false-alarm rate. In 1985, a new TSO-C91A ELT was developed, which substantially reduces or eliminates many problems with the earlier model. The TSO-C91A provides improved performance and reliability (with an activation rate of 73 percent in actual crashes) at a reasonable cost to users ($200-$500 including installation). Since then, an even more advanced model of ELT has been developed — the C126 ELT (406 MHz). This newest model activates 81-83 percent of the time and transmits a more accurate and near-instantaneous emergency signal by utilizing digital technology. This digital 406-MHz ELT also allows search and rescue personnel to have vital information specific to you and your aircraft. These ELTs are more expensive, however, with the current cost around $1,000 or more per unit, not including installation.

ELTs were originally intended for use on the 121.5-MHz frequency to alert air traffic control and aircraft monitoring the frequency. In 1982 a satellite-based monitoring system was implemented (COSPAS-SARSAT) to provide a better receiving source for these signals. As of February 1, 2009, the international COSPAS-SARSAT satellite system will discontinue satellite-based monitoring of the 121.5/243-MHz frequencies, in part because of a high number of false signals attributed with these frequencies. While there's no requirement in the United States to replace the first- and second-generation 121.5-MHz ELTs, after this date, 121.5/243-MHz distress signals transmitted from ELTs operating on the lower frequency will only be detected by ground-based receivers such as local airport facilities and air traffic control facilities or by overflying aircraft. It is important to note that after 2009, existing 121.5-MHz ELTs, although still legal from the FAA's perspective, will provide extremely limited assistance if an aircraft crashes, especially in a remote location.
Title: Re: ELT STANDARDS
Post by: Airrace on November 27, 2009, 05:23:43 PM
Quote from: rescue520 on November 27, 2009, 08:15:29 AM
G'Day all
I was just wondering if anyone knew where i could find the Standards for ELT's?
Not after the carriage requirements but more specifically
Frequencys requriements - 406 121.6 243 etc
Min operating time
cold shock requirement etc.
I have all the information on PLB's & EPIRBS but unable to find the ELT
Thanks for your help in advance
Rescue

I have had good luck doing a goggle search.
Title: Re: ELT STANDARDS
Post by: 321EOD on November 28, 2009, 01:25:18 AM
Quote from: rescue520 on November 27, 2009, 08:15:29 AM
G'Day

Hey 520, are you an aussie? Don't see "G'day" used much on CAPTALK!