Luke Skywalker
Super Moderator
{vb:raw ozzmodz_postquote}:
- Malaysia Airlines Flight 370 had four beacons, or emergency locator transmitters
- One was designed to activate on impact, but satellites did not receive a distress signal
- The lack of a distress signal boosts hopes of passengers' families
(CNN) -- It is one of the most enduring mysteries of Malaysia Airlines Flight 370, and for the families, it's a reason for hope.
Why didn't Flight 370's emergency beacon work?
Why didn't the beacon send a distress signal to satellites overhead?
And the clincher: Why, if the beacon is designed to activate on impact, should we believe there was an impact? Could the plane have landed intact? Could the 239 passengers and crew still be alive?
An autonomous underwater vehicle is brought back aboard the Australian ship Ocean Shield after a search mission for the missing Malaysia Airlines Flight 370 in the southern Indian Ocean on Saturday, April 19. Searchers are combing thousands of square miles of the ocean for signs of Flight 370, which disappeared March 8.
A Royal Malaysian Air Force plane takes off from an airbase near Perth, Australia, to help in the search on Thursday, April 17.
Operators aboard the Australian ship Ocean Shield move Bluefin-21, the U.S. Navy's autonomous underwater vehicle, into position to search for the jet on Monday, April 14.
A member of the Royal New Zealand Air Force looks out of a window while searching for debris off the coast of western Australia on Sunday, April 13.
British Royal Navy sailors aboard the vessel HMS Echo take part in the search for the jet on April 13.
Crew members aboard the Echo watch a smaller boat that's part of the British search effort on April 13.
The Echo moves through the waters of the southern Indian Ocean.
A map provided Saturday, April 12, details efforts to find the missing jet.
Chinese navy personnel head out on a boat to the Royal Australian Navy ship HMAS Success on Wednesday, April 9.
A Royal Australian Air Force AP-3C Orion, on a mission to drop sonar buoys to assist in the search, flies past the Australian vessel Ocean Shield on April 9.
A relative of a missing passenger cries at a vigil in Beijing on Tuesday, April 8.
A member of the Royal Australian Air Force walks toward a plane that just arrived in Perth on April 8.
Australian Defense Force divers scan the water for debris Monday, April 7, in the southern Indian Ocean.
A towed pinger locator is readied to be deployed April 7 off the deck of the Australian vessel Ocean Shield.
Capt. Mark Matthews of the U.S. Navy talks to reporters in Perth about the search on April 7.
A member of the search operation points to a map outlining search areas during a news conference April 7 in Perth.
A U.S. Navy airplane takes off from Perth to assist in the search on April 7.
A member of the Royal New Zealand Air Force looks at a flare in the Indian Ocean during search operations on Friday, April 4.
Members of the Royal New Zealand Air Force monitor data April 4 on board an aircraft during search operations.
A relative of a Flight 370 passenger watches television in a Beijing hotel as he awaits new information about the missing plane on Thursday, April 3.
Another relative of a Flight 370 passenger waits for updates in Beijing on Wednesday, April 2. Many families have criticized the Malaysian government's handling of information in the plane's disappearance.
A member of the Japanese coast guard points to a flight position data screen while searching for debris from the missing jet on Tuesday, April 1.
Kojiro Tanaka, head of the Japanese coast guard search mission, explains the efforts en route to the search zone April 1.
A woman prepares for an event in honor of those aboard Flight 370 on Sunday, March 30, in Kuala Lumpur, Malaysia.
An underwater search-surveying vehicle sits on the wharf in Perth, ready to be fitted to a ship to aid in the search for the jet.
A girl in Kuala Lumpur writes a note during a ceremony for the missing passengers on March 30.
A teary-eyed woman listens from the back as other relatives of Flight 370 passengers speak to reporters March 30 in Subang Jaya, Malaysia. Dozens of anguished Chinese relatives demanded that Malaysia provide answers to the fate of those on board.
An object floating in the southern Indian Ocean is seen from a Royal New Zealand Air Force P-3K2 Orion aircraft searching for the missing jet on Saturday, March 29. Ships participating in the search retrieved new debris Saturday, but no objects linked to the missing plane, according to Australian authorities.
A Royal New Zealand Air Force member launches a GPS marker buoy over the southern Indian Ocean on March 29.
The sole representative for the families of Flight 370 passengers leaves a conference at a Beijing hotel on Friday, March 28, after other relatives left en masse to protest the Malaysian government's response to their questions.
A member of the Royal Australian Air Force is silhouetted against the southern Indian Ocean during the search for the missing jet on Thursday, March 27.
Flight Lt. Jayson Nichols looks at a map aboard a Royal Australian Air Force aircraft during a search on March 27.
People in Kuala Lumpur light candles during a ceremony held for the missing flight's passengers on March 27.
Crew members of the Chinese icebreaking ship Xuelong scan the Indian Ocean during a search for the missing jet on Wednesday, March 26.
People work at a console at the British satellite company Inmarsat on Tuesday, March 25, in London.
The mother of a passenger who was on Malaysia Airlines Flight 370 cries at her home in Medan, Indonesia, on March 25.
Australian Defense Minister David Johnston speaks to the media March 25 about the search for the missing jet.
A family member of a missing passenger reacts after hearing the latest news March 25 in Kuala Lumpur.
Angry relatives of those aboard Malaysia Airlines Flight 370 react in Beijing on Monday, March 24, after hearing that the plane went down over the southern Indian Ocean, according to analysis of satellite data.
Grieving relatives of missing passengers leave a hotel in Beijing on March 24.
Malaysian Prime Minister Najib Razak, center, delivers a statement about the flight March 24 in Kuala Lumpur. Razak's announcement came after the airline sent a text message to relatives saying it "deeply regrets that we have to assume beyond any reasonable doubt that MH 370 has been lost and that none of those onboard survived."
Relatives of the missing passengers hold a candlelight vigil in Beijing on March 24.
A member of the Royal Australian Air Force looks out an aircraft during a search for the missing jet March 24.
A woman reads messages for missing passengers at a shopping mall in Kuala Lumpur on March 24.
Flight Lt. Josh Williams of the Royal Australian Air Force operates the controls of an AP-3C Orion on Sunday, March 23, after searching the southern Indian Ocean.
Ground crew members wave to a Japanese Maritime Defense Force patrol plane as it leaves the Royal Malaysian Air Force base in Subang, Malaysia, on Sunday, March 23. The plane was heading to Australia to join a search-and-rescue operation.
A passenger views a weather map in the departures terminal of Kuala Lumpur International Airport on Saturday, March 22.
A Chinese satellite captured this image, released on March 22, of a floating object in the Indian Ocean, according to China's State Administration of Science. It is a possible lead in the search for the missing plane. Surveillance planes are looking for two objects spotted by satellite imagery in remote, treacherous waters more than 1,400 miles from the west coast of Australia.
A member of the Royal Australian Air Force looks down at the Norwegian merchant ship Hoegh St. Petersburg, which took part in search operations Friday, March 21.
The Royal Australian Air Force's Neville Dawson, left, goes over the search area with Brittany Sharpe aboard an AP-3C Orion some 2,500 kilometers (about 1,500 miles) southwest of Perth, Australia, over the Indian Ocean on March 21.
Satellite imagery provided by the Australian Maritime Safety Authority on Thursday, March 20, shows debris in the southern Indian Ocean that could be from Flight 370. The announcement by Australian officials that they had spotted something raised hopes of a breakthrough in the frustrating search.
A closer look at the satellite shot of possible debris from Malaysia Airlines Flight 370.
Another satellite shot provided by the Australian Maritime Safety Authority shows possible debris from the flight.
A closer look at the satellite shot of possible debris.
The Australian Maritime Safety Authority's John Young speaks to the media in Canberra, Australia, on March 20 about satellite imagery.
A distraught relative of a missing passenger breaks down while talking to reporters at Kuala Lumpur International Airport on Wednesday, March 19.
A relative of missing passengers waits for a news briefing by officials in Beijing on Tuesday, March 18.
A relative of a missing passenger tells reporters in Beijing about a hunger strike to protest authorities' handling of information about the missing jet.
A member of Indonesia's National Search and Rescue Agency joins in a search for the missing plane in the Andaman Sea area around the northern tip of Indonesia's Sumatra on Monday, March 17.
Relatives of missing passengers watch a news program about the missing plane as they await information at a hotel ballroom in Beijing on March 17.
Malaysian Transportation Minister Hishamuddin Hussein, center, shows maps of the search area at a hotel next to the Kuala Lumpur International Airport on March 17.
U.S. Navy crew members assist in search-and-rescue operations Sunday, March 16, in the Indian Ocean.
Indonesian personnel watch over high seas during a search operation in the Andaman Sea on Saturday, March 15.
A foam plane, which has personalized messages for the missing flight's passengers, is seen at a viewing gallery March 15 at Kuala Lumpur International Airport.
A member of the Malaysian navy makes a call as his ship approaches a Chinese coast guard ship in the South China Sea on March 15.
A Indonesian ship heads to the Andaman Sea during a search operation near the tip of Sumatra, Indonesia, on March 15.
Elementary school students pray for the missing passengers during class in Medan, Indonesia, on March 15.
Col. Vu Duc Long of the Vietnam air force fields reporters' questions at an air base in Ho Chi Minh City, Vietnam, after a search operation on Friday, March 14.
Members of the Chinese navy continue search operations on Thursday, March 13. The search area for Flight 370 has grown wider. After starting in the sea between Malaysia and Vietnam, the plane's last confirmed location, efforts are expanding west into the Indian Ocean.
A Vietnamese military official looks out an aircraft window during search operations March 13.
Malaysian air force members look for debris on March 13 near Kuala Lumpur.
A relative of a missing passenger watches TV at a Beijing hotel as she waits for the latest news March 13.
A member of the Indonesian National Search and Rescue Agency scans the horizon in the Strait of Malacca on Wednesday, March 12.
Relatives of missing passengers wait for the latest news at a hotel in Beijing on March 12.
Journalists raise their hands to ask questions during a news conference in Sepang on March 12.
Indonesian air force officers in Medan, Indonesia, examine a map of the Strait of Malacca on March 12.
A member of the Vietnamese air force checks a map while searching for the missing plane on Tuesday, March 11.
Iranians Pouri Nourmohammadi, second left, and Delavar Seyed Mohammad Reza, far right, were identified by Interpol as the two men who used stolen passports to board the flight. But there's no evidence to suggest either was connected to any terrorist organizations, according to Malaysian investigators. Malaysian police believe Nourmohammadi was trying to emigrate to Germany using the stolen Austrian passport.
An Indonesian navy crew member scans an area of the South China Sea bordering Indonesia, Malaysia and Thailand on Monday, March 10.
Vietnam air force Col. Le Huu Hanh is reflected on the navigation control panel of a plane that is part of the search operation over the South China Sea on March 10.
Relatives of the missing flight's passengers wait in a Beijing hotel room on March 10.
A U.S. Navy Seahawk helicopter lands aboard the USS Pinckney to change crews before returning to search for the missing plane Sunday, March 9, in the Gulf of Thailand.
Members of the Fo Guang Shan rescue team offer a special prayer March 9 at Kuala Lumpur International Airport.
A handout picture provided by the Malaysian Maritime Enforcement Agency shows personnel checking a radar screen during search-and-rescue operations March 9.
Italian tourist Luigi Maraldi, who reported his passport stolen in August, shows his current passport during a news conference at a police station in Phuket island, Thailand, on March 9. Two passengers on the missing Malaysia Airlines flight were reportedly traveling on stolen passports belonging to Maraldi and an Austrian citizen whose papers were stolen two years ago.
Hugh Dunleavy, commercial director of Malaysia Airlines, speaks to journalists March 9 at a Beijing hotel where relatives and friends of the missing flight's passengers are staying.
Vietnamese air force crew stand in front of a plane at Tan Son Nhat airport in Ho Chi Minh City on March 9 before heading out to the area between Vietnam and Malaysia where the airliner vanished.
Buddhist monks at Kuala Lumpur International Airport offer a special prayer for the missing passengers on March 9.
The Chinese navy warship Jinggangshan prepares to leave Zhanjiang Port early on March 9 to assist in search-and-rescue operations for the missing Malaysia Airlines flight. The Jinggangshan, an amphibious landing ship, is loaded with lifesaving equipment, underwater detection devices and supplies of oil, water and food.
Members of a Chinese emergency response team board a rescue vessel at the port of Sanya in China's Hainan province on March 9. The vessel is carrying 12 divers and will rendezvous with another rescue vessel on its way to the area where contact was lost with Malaysia Airlines Flight 370.
The rescue vessel sets out from Sanya in the South China Sea.
A family member of missing passengers is mobbed by journalists at Kuala Lumpur International Airport on Saturday, March 8.
A Vietnamese air force plane found traces of oil that authorities had suspected to be from the missing Malaysia Airlines plane, the Vietnamese government online newspaper reported March 8. However, a sample from the slick showed it was bunker oil, typically used to power large cargo ships, Malaysia's state news agency, Bernama, reported on March 10.
Malaysian Prime Minister Najib Razak, center, arrives to meet family members of missing passengers at the reception center at Kuala Lumpur International Airport on March 8.
Malaysia Airlines official Joshua Law Kok Hwa, center, speaks to reporters in Beijing on March 8.
A relative of two missing passengers reacts at their home in Kuala Lumpur on March 8.
Wang Yue, director of marketing of Malaysia Airlines in China, reads a company statement during a news conference at the Metro Park Lido Hotel in Beijing on March 8.
Chinese police at the Beijing airport stand beside the arrival board showing delayed Flight 370 in red on March 8.
A woman asks a staff member at the Beijing airport for more information on the missing flight.
A Malaysian man who says he has relatives on board the missing plane talks to journalists at the Beijing airport on March 8.
Passengers walk past a Malaysia Airlines sign on March 8 at Kuala Lumpur International Airport.
Malaysia Airlines Group CEO Ahmad Juahari Yahya, front, speaks during a news conference on March 8 at a hotel in Sepang. "We deeply regret that we have lost all contacts" with the jet, he said.
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
The search for Malaysia Airlines Flight 370
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
Photos: The search for Malaysia Airlines Flight 370
The issue resonates with some family members looking for hope where little exists. Of the 26 questions families recently presented to the Malaysian government, 12 addressed the beacon.
Adding to the mystery: Hijackers or renegade pilots cannot disable emergency beacons. They are powered by batteries and inaccessible to the crew. So by all accounts, the beacon on Flight 370 should have activated if the plane crashed.
But experts consulted by CNN say there are numerous reasons why a beacon could fail in an ocean crash.
A look back at the saga of MH370
Malaysian PM responds to search criticism
MH370 families protest outside embassy
The beacon itself could be damaged by the impact, or its antenna could be sheared from the fuselage, rendering it inoperable.
And there's one other possibility considered even more likely by some: The crash impact may have actually activated the beacon, but the damaged plane sank in less than 50 seconds, the time necessary for it to transmit its first emergency signal. The beacons do not work underwater.
On Friday, 49 days after Flight 370 disappeared, no one can say with certainty what happened with the plane's beacons.
That has left some family members with a faint glimmer of hope, but others believing that the beacon system just failed.
What are beacons?
Beacons -- more formally called emergency locator transmitters, or ELTs -- are devices that transmit an electronic distress signal in the event of a crash.
Malaysia Flight 370 had four of them, Malaysian officials told CNN.
Two of the ELTs were stored with the airplane's life raft, to be activated by hand or by contact with the water, if the life boats were deployed.
The third ELT was stowed in the cabin.
But the ELT of greatest interest is the remaining "fixed" ELT, mounted to the aircraft frame. The fixed ELT -- a Honeywell RESCU 406 AFN -- was positioned near the rear door and connected to an antenna on top of the aircraft. It could be activated, either manually by a pilot in the cockpit, or automatically upon impact, by an inertial "G-switch."
The RESCU 406 AFN was designed "to provide emergency transmission for aircraft flying over land," according to Honeywell's published specifications.
MH370: Bluefin-21 search nearly complete
"They are not mandated or designed to work under water," a Honeywell spokesman told CNN.
But experts say any impact -- whether on land or at sea -- likely would have activated the transmitter.
Once activated, the device simultaneously transmits "bursts" -- short, digitally coded signals -- on three frequencies. Two of the frequencies -- 243 MHz and 121.5 MHz -- are VHF frequencies and can help search planes hone in on a target. The third frequency is 406 MHz.
That's where satellites come in.
Help from above
In 1979, the United States, Canada, France and the former Soviet Union teamed up to provide a global, satellite-based system to detect emergency beacons activated by planes, ships and backcountry hikers and to distribute those alerts to rescuers.
Known as the International Cospas-Sarsat Programme, the enterprise claimed it made its first rescue in September 1982, saving three people involved in the crash of a light aircraft in Canada.
"Cospas-Sarsat has done an enormous amount of good in the world, but almost nobody has ever heard of us," said Steven Lett, an American diplomat and head of the Cospas-Sarsat Secretariat in Montreal.
Cospas-Sarsat relies on six low-altitude, Earth-orbiting satellites and six high-altitude geostationary satellites, each with advantages and disadvantages.
The six low-altitude satellites, whose main function is to provide meteorological information, orbit the poles and give complete but non-continuous coverage of the Earth's surface. Because they can only view a portion of the Earth at any given time, the satellite may need to store geographic information from an emergency beacon and rebroadcast it when it comes within view of a ground facility.
The six geostationary satellites, parked in spots more than 22,000 miles above the equator, cover most of the Earth's surface but cannot determine the location of the beacon unless the location is encoded in the signal.
All of the satellites listen for a beacon's 406 MHz signals and together can identify a beacon's location to within approximately 3 kilometers, or just under 2 miles.
If Flight 370's ELT had transmitted a 406 MHz signal, it "almost certainly would have been picked up by one of the geostationary satellites," Lett said. Two satellites, India's Insat-3A and Russia's Electro-L1, are both parked over the Indian Ocean. It perhaps would have also been picked up by an orbiting low-altitude satellite.
Australia, Singapore, Indonesia and China all have antennas that monitor the satellites' emergency transmitter. Some or all of them likely would have received the distress call.
But authorities say no satellite signals were sent. No rescue was launched.
Other rescues
Cospas-Sarsat said about five people are rescued every day with the assistance of the satellite system.
But the disappearance of large commercial jetliners is very rare, and consequently, so is the discovery of them.
Cospas-Sarsat said it was instrumental in finding a Varig Airlines B-737 that wandered off course and crashed in the Brazilian jungle in September 1989. And when a Turkish Airlines B-737 dropped off radar near Schiphol Airport in the Netherlands in 2009, an ELT alert was the first confirmation to controllers that the aircraft had crashed.
The organization also said it was the primary or sole source of location information in about 25 other cases involving aircraft with 10 or more passengers.
Somewhere in the Indian Ocean
What can explain the lack of a signal in the Flight 370 case?
Assuming that the device was working correctly, the crash could have broken the antenna or cut the connection with the ELT, rendering it useless.
Another possibility, experts say, is that the aircraft could have sunk before the ELT began transmitting. It takes 50 seconds for the ELT to establish the necessary connection. It only takes one half-second data "burst" to indicate there is an emergency. But it can take a half-dozen bursts -- at the rate of one every 50 seconds -- to provide information that will allow Cospas-Sarsat to triangulate the beacon's position.
"In this case, there wasn't even one burst, according to the reports that we received," Lett said.
If the plane crashed in the southern Indian Ocean, as Malaysia Airline officials believe, the lack of a distress call could indicate that the plane plunged into the water, or sank quickly, because once underwater, the beacon is ineffective.
Likewise, the water-triggered ELTs in the life rafts would be ineffective if they became submerged, according to published Honeywell manuals for the devices.
Cospas-Sarsat also notes that beacons must have a relatively unobstructed view of the sky to work properly.
"A submerged beacon, or one with its antenna blocked by the body of an aircraft or vessel, is unlikely to be received by the satellites," the organization said.
Said Honeywell Aerospace spokesman Steven Brecken: "Until the recorders are recovered, we don't want to speculate what could or could not have happened. We ask the same thing you do, why didn't the ELT operate? We don't have the answer."
Family questions
In a recent letter to Malaysian authorities, a family group showered them with questions about the ELTs.
How many ELTs are on the plane, they asked, adding that they had gotten conflicting numbers.
Did Malaysia Airlines conduct maintenance checks? When was the latest check for MH370's ELT?
They asked to see the results of those checks.
Was the 406 MHz beacon certified? Was it possible to break the ELT in a crash? Where exactly was it located?
Would the ELT signal be weakened if it was surrounded by metal? Was the cable and blade antenna 9G certified? How much impact is needed to activate the ELT? Had the crew been trained in the use of ELTs? Can a beacon unlock "and bounce [float] to the surface of the water?"
Many of the questions remain unanswered.
But Cospas-Sarsat officials said that previous accidents have exposed shortcomings with the system and that they are working to improve it.
Among other things, they are testing a new constellation of mid-altitude satellites that can better determine the location of an ELT.
And government and industry officials are working on a new generation of ELTs that can monitor a plane conditions, identify problems and send a distress signal before the plane ever reaches the ground.
Or the sea.
