Skip to main content

MH370: Is it the pinger? 4 reasons to believe; 6 reasons to doubt

By Mike M. Ahlers, CNN
April 7, 2014 -- Updated 0215 GMT (1015 HKT)
  • Are the pulses detected by a Chinese patrol ship MH370's pingers?
  • The frequency and location are indications they might be
  • There are also a number of reasons to doubt the latest lead

(CNN) -- After weeks of fruitless searching for the missing Malaysia Airlines plane, it sounds like a promising sign.

When a Chinese patrol ship picked up two pulses in the southern Indian Ocean, the head of the Australian agency coordinating search efforts called it "an important and encouraging lead."

Investigators hope the audio signals are locator beacons from the plane's data recorders, but they're not sure yet.

Is it the discovery we've all been waiting for? Could those be Malaysia Airlines Flight 370's pingers?

Here are four reasons to believe and six reasons to doubt:


1) The frequency doesn't occur in nature.

The Chinese Haixun 01 patrol ship detected pulses at a frequency of 37.5 kHz, the Chinese state-run Xinhua news agency reported. That's the same frequency of black box pingers -- and that frequency is no accident. The pingers were designed to have that frequency because it does not occur in nature.

2) There were two separate events.

The Haixun 01 reported two pulses within 2 kilometers (1.25 miles) of each other. Air Chief Marshal Angus Houston, head of the Joint Agency Coordination Center, described them as "fleeting, fleeting acoustic events." One was described as being 90 seconds long; no time was given for the other, but it was evidently shorter.

"I think the fact that we have had two detections, two acoustic events, in that location provides some promise which requires a full investigation of the location," Houston said.

Australia cautions about false positives
Another 'acoustic event' detected
China: Pulse signals lasted over a minute

3) You usually know a ping when you hear one.

The pings are, under ideal conditions, easily recognizable. They "ping" like a metronome — with a steady pulse about once a second.

4) They're in the right spot.

According to the latest analysis of Inmarsat satellite data and aircraft performance, the Haixun 01 is in the right spot. In fact, search supervisors, citing the new analysis, are moving the focus of the search to an area that includes the location of the Haixun 01.

"The area of highest probability, we think is now probably in the southern part of the area, pretty close to where Haixun 01 is operating," Houston said.

Pulse signals raise new questions


1) The ocean is noisy.

In addition to the Haixun 01's two "acoustic events," ships detected two other events in a very short time, showing exactly how noisy the ocean is.

The British ship HMS Echo recorded one event that was determined to be unfounded. The Ocean Shield, an Australian naval vessel equipped with sophisticated listening equipment, has also detected "an acoustic noise" in another area of the ocean to the north. According to a CNN calculation, the Australian ship was about 350 miles (565 kilometers) away from the spot where the Chinese ship detected the pulses. It's also unclear whether the sound the Australian ship detected was related to Flight 370.

The search team is urging patience and restraint.

2) Only one pulse was detected at a time.

The Haixun 01 detected only one pulse at a time. Assuming both black box pingers are working, are close together, and are unobstructed by debris or terrain — and those are, admittedly, big assumptions — they should have heard two pingers, perhaps like a metronome with an echo.

Pinger locator: A shot in the dark?
What's inside of a black box?
Will MH370's black box ever be found?

3) These aren't ideal conditions.

While pingers are easily identifiable under ideal conditions, the current conditions are far from perfect. Video of the searchers show them listening to the hydrophone with earbuds, not headsets that would block out ambient noise.

So the steady "pings" -- which actually sound like the snap of fingers -- could be confused with or overwhelmed by other noise, such as the waves lapping against the boat.

The Chinese said they did not have time to record the pulses, precluding a scientific analysis of the sounds.

4) A spare pinger on the boat might have sent the signal.

In video of the Haixun 01, it appears the Chinese had a spare pinger in the boat.

Anish Patel, president of pinger manufacturer Dukane Seacom, says it is not recommended to have a pinger near the area where you are trying to listen.

If that pinger gets wet, it will start transmitting, potentially confusing search teams.

"I wouldn't put one where I'm measuring," Patel said. "It's just not good common practice."

5) The equipment was designed for shallow water.

The hydrophone the Chinese used to detect the pulse is "designed for shallow water applications," not for the deep water, said Thomas Altshuler of Teledyne Marine Systems, manufacturer of the hydrophone.

"They are using it in a scenario outside of our normal operation," he said.

Is it possible that it heard a ping from the depths of the Indian Ocean?

"It is possible, but it would be right at the edge of that detection (capability)," he said.

6) The underwater search of a vast area started only recently.

The search area is so large, and the underwater search has just begun. It almost defies belief that the pingers could be found so soon. But then again, almost everything about this case defies belief.


We'll give the final word to Angus Houston.

"This is an important encouraging lead, but one which I urge you to continue to treat carefully," he told reporters. "We are working in a very big ocean and within a very large search area, and so far, since the aircraft went missing, we have had very few leads which allow us to narrow the search area."

CNN's Aaron Cooper and Catherine E. Shoichet contributed to this report.

Part of complete coverage on
June 26, 2014 -- Updated 2211 GMT (0611 HKT)
The search for MH370 is moving to an area farther south in the Indian Ocean, said the Australian Deputy Prime Minister.
June 25, 2014 -- Updated 0033 GMT (0833 HKT)
Erin Burnett speaks to Miles O'Brien about the latest in the search for Malaysia Airlines Flight 370.
June 18, 2014 -- Updated 1653 GMT (0053 HKT)
Ten experts say that the search for MH370 should move hundreds of miles away from the previous search area.
June 17, 2014 -- Updated 1322 GMT (2122 HKT)
His wife never came home from her flight on MH370, and now K.S. Narendran is left to imagine the worst of possible truths without knowing.
June 16, 2014 -- Updated 1951 GMT (0351 HKT)
Families are desperate for results as the search for MH370 reaches a grim milestone. Anna Coren reports from Beijing.
June 9, 2014 -- Updated 1455 GMT (2255 HKT)
Relatives of passengers are launching an effort to raise $5 million for investigations and a "whistle blower" reward.
June 9, 2014 -- Updated 0731 GMT (1531 HKT)
Making sure another plane is never "lost" again is the immediate priority for the airline industry.
May 30, 2014 -- Updated 1536 GMT (2336 HKT)
This handout photo taken on April 7, 2014 and released on April 9, 2014 by Australian Defence shows Maritime Warfare Officer, Sub Lieutenant Ryan Penrose watching HMAS Success as HMAS Perth approaches for a replenishment at sea while searching for missing Malaysia Airlines flight MH370 in the southern Indian Ocean. Two fresh signals have been picked up Australian ship Ocean Shield in the search for missing Malaysian flight MH370, raising hopes that wreckage will be found within days even as black box batteries start to expire.
Was the sound of Malaysian Airlines Flight MH370 striking the water captured by ocean devices used to listen for signs of nuclear blasts?
May 28, 2014 -- Updated 2229 GMT (0629 HKT)
What was believed to be the best hope of finding the missing plane is now being called a false hope. Rene Marsh explains.
May 28, 2014 -- Updated 2105 GMT (0505 HKT)
Involved parties, including the manufacturer Boeing, are bracing for a long public relations siege.
May 29, 2014 -- Updated 1134 GMT (1934 HKT)
Official: The four acoustic pings at the center of the search for Flight 370 are no longer believed to have come from the plane's black boxes.
May 27, 2014 -- Updated 1421 GMT (2221 HKT)
There is one fundamental question which continues to swirl: Has Inmarsat got its numbers right?
May 27, 2014 -- Updated 1213 GMT (2013 HKT)
Data from communications between satellites and missing Malaysian Airlines Flight 370 was released
May 27, 2014 -- Updated 0742 GMT (1542 HKT)
Family members of the people aboard missing plane want independent investigators to review the newly released satellite data.
May 21, 2014 -- Updated 1147 GMT (1947 HKT)
CNN's Richard Quest explains what kind of information should be contained in the Inmarsat data from Flight MH370.
May 27, 2014 -- Updated 0046 GMT (0846 HKT)
The underwater search for the missing Malaysia Airlines plane will effectively be put on hold this week, and may not resume until August at the earliest.
May 19, 2014 -- Updated 1304 GMT (2104 HKT)
Movie-makers in Cannes have announced they're making a thriller based on the disappearance of Malaysian flight MH370.
May 6, 2014 -- Updated 1925 GMT (0325 HKT)
The search for the missing Boeing 777 has gone on for eight weeks now. CNN's David Molko looks back at this difficult, emotional assignment.