Emergency aircraft navigation device

The emergency locator designed on each aircraft can be the focal point to help rescue forces locate aircraft in certain circumstances.

The Emergency Positioning Unit (ELT) is a device designed for commercial aircraft, which can signal when the aircraft is in distress. When the plane falls, the ELT unit will automatically turn on immediately to send a signal so that the search force can determine the plane's falling position.

According to aviation safety expert Todd Curis, ELT is basically a reliable part. However, it is still possible that this system does not work in some cases for some reason.

Photos: nbcnews

A report by the Pilot and Aircraft Association (AOPA) in 2009 found that the rate of early generation ELT generations, dating back to 1973, was about 25%. This rate is improved over time with the support of modern technology. However, even for new ELT devices, the likelihood of successful activation is only 82%.

The signal of the ELT is synonymous with the ability to continue broadcasting information within 30 days. In the case of aircraft and ELT on the ground, if this signal is received, rescuers can find aircraft thanks to satellites, high-altitude search engines or other modern technologies.

"If the plane falls on land and there is a collision, the ELT department can still work," NBC News quoted Greg Feith, an investigator from the US National Traffic Safety Agency. However, if the plane falls into the sea, everything happens in the other direction.

In that case, the underwater positioning device (ULB) transmitter in the black box of the aircraft will emit "ping ping" sounds . These sounds can be heard if the search force approaches close enough to the location of the device. Signals will not be determined if search activity relies solely on overhead planes.

In addition to ELT, the search team can also use ultrasound transmitters to determine the location of undersea aircraft. However, David Gallo, an expert at Woods Hole Oceanographic Institution, USA, said he did not believe in the accuracy of ultrasound transmitters if used to search for missing planes, by operation. In the ocean heart can create many fake sounds.

After four days of searching for Malaysia Airlines' missing aircraft without any positive signs, experts say it is not surprising that no emergency signals have been recorded, especially if the The plane has fallen into the sea.

Representatives of Boeing's commercial aircraft manufacturer have yet to make any comment on the type of ELT designed on the missing Boeing 777-200 aircraft. According to the experience of Curtis, who worked for Boeing for more than 8 years as an aircraft safety engineer, Malaysia Airlines may have updated the new ELT version.