NTSB Safety Alert SA-030 - Armed for Safety Emergency Locator Transmitters

“Armed” for Safety: Emergency Locator Transmitter s

Verify your ELT is switched on and attached to your aircraft to

ensure it will work when need ed

The problem

 ELTs can save pilots’ and passengers’ lives by helping search and res cue (SAR) personnel

locate a downed aircraft after an accident and even minimize risk to SAR personnel during SAR

operations . However , these lifelines can be rendered inoperative if the switch position is

improperly set or if the ELT becomes d etach ed from the aircraft .

 As of December 2013, a bout 180,000 general aviation aircraft were equipped with ELTs that

had 121.5 -megahertz (MHz) transmitters , which are less e ffective than 406-MHz transmitters .

At that time, o nly about 38,000 general aviation aircraft were equipped with 406 -MHz ELTs.

Related accidents

Several NTSB accident investigations have found ELT switch es in the “off” position (thus, not “ armed ”)

and ELTs detached from the airplane, which rendered them inoperable. In these cases, the inoperability

of the ELTs delayed the aircraft’s discovery and /or the rescue of occupants. The NTSB is concerned

that these examples of ELT issues represent a more widespread problem t hat could endanger the lives

of pilots and passengers who survive an aircraft accident in a remote area.

 A pilot and passenger died when a Cessna A185F airplane impacted terrain. Although the flight

instructor on board initially survived the accident, he died due to serious injuries before the

airplane was found. After the airplane had not returned to the departure airport by nighttime,

fixed -base -operator personnel checked data from the flight instructor’s personal locator , which

was configured to send GPS position reports about every 10 minutes , and noted that the

transmissions from the previous 12 hours had been sent from the same location . No emergency

or alert notifications were received from the personal locator or the airplane’s ELT during that

period. SAR efforts were then initiated, and the wreckage was located the next day. The

personal locator was found ejected from the airplane . Although the airplane was equipped with

a 406 -MHz ELT that activated during the accident, it had become separated fro m the airplane’s

structure (and thus its antenna), which limited its transmission range and prevented it from

effectively transmitting an alert signal and providing SAR personnel with a rapid indication that

an accident had occurred. With prompt ELT notifi cation, medical response would have been

initiated in a timely manner , and the flight instructor might not have succumbed to his serious

injuries . (NTSB accident number WPR12FA184 )

 An airline transport pilot and four passengers died and four passengers sustained serious

injuries when a de Havilland DHC -3T airplane impacted terrain. A search for the airplane was

not initiated until hours after it had crashed because its overdue status was not noticed right

away, and no signals from its ELT were received. The investigation found that the ELT, which

was secured by a hook -and-loop style (Velcro) mounting mechanism, was dislodged from its

mounting tra y and detached from its antenna, thus the radio signals from the ELT were not

transmitted. If the ELT had remained attached to its antenna, its signals likely would have been

SA-030 December 2013 , revised December 2015

detected soon after impact, and rescue personnel would have received timely notif ication of the

accident and its location and could have reached the survivors hours earlier. ( ANC10MA068

and NTSB report number AAR-11/03 )

 A private pilot died when a Cessna 182D airplane collided with terrain about 35 miles from the

flight’s intended destination. After the flight failed to arrive, concerned family members contacted

the FAA. SAR operations commenced, but the wreckage was not located until a week later. The

121.5 -MHz ELT switch was found in the “off” position. SAR personnel flew almost directly over

the accident site with monitoring equipment that could detect 121.5 MHz; therefore, although

in this case an operable ELT would not have saved the pilot’s life, if the ELT switch had been

armed, SAR personnel would not hav e been as extensively exposed to severe weather

conditions during the SAR operations. (WPR13FA053 )

What can pilots, aircraft owners , and maintenance technicians do?

 Confirm that the ELT unit is “armed” and properly installed in the aircraft .

 Follow manufacturer instructions for properly securing the ELT and inspecting the fasteners.

 Remember that ELTs secure d to the aircraft via Velcro -style mounting mechanisms can be

susceptible to strap looseness and misalignment during installation and inspection. Further, the

retention straps may degrad e over time due to wear, vibration, temperature, or contamination ,

and they may not properly restrain the ELT during an acci dent.

 Consider upgrading to a 406 -MHz ELT , which the NTSB has long recommende d be mandatory

due to its superior position accuracy reporting, timeliness of alerts, and ability to provide aircraft

identification and other information .

Interested in more information?

The reports for the accidents referenced in this safety alert are accessible by NTSB accident number

from the NTSB’s Aviation Accident Database & Synopses web page at

www.ntsb.gov/aviationquery/index.aspx. Each accident’s public docket is accessible from the NTSB’s

Docket Management System web page at http://dms.ntsb.gov/pubdms/.

FAA Advisory Circular ( AC) 91-44A, “Operational and Maintenance Practices for Emergency Locator

Transmitters and Receivers ,” provide s guidance information , in part, about ELT operational

characteristics, mo unting mechanisms, maintenance, and testing. A link to the AC can be accessed

from the FAA’s AC web page at http://www.faa.gov/regulations_policies/advisory_circulars/ .

The NTSB has issued safety recommendations , including A-99-63, A-07-51, and A-10-169 and -170, to

the FAA regarding ELT technological standards (rec ommending 406-MHz ELTs or equivalent

technology ), mounting requirements , and retention tests . These recommendations can be accessed

from the NTSB’s safety recommendations query page at http://www.ntsb.gov/safety/safety -

recs/_layouts/ntsb.recsearch/RecTabs.aspx .

Special Airworthiness Information Bulletin (SAIB) HQ-12-32, “ Hook and Loop Style Fasteners as a

Mounting Mechanism for Emergency Locator Transmitters (ELTs) ,” which was issued in response to

NTSB Safety Recommendation A -10-170, discusses problems with certain ELT fasteners. A link to the

SAIB can be accessed from the FAA’s regula tions and policies web page at

www.faa.gov/regulations_policies/ .

This NTSB safety alert and others can be accessed from the NTSB’s Safety Alerts web page at

http://www.ntsb.gov/safety/safety -alerts/Pages/default.aspx .