Monday, May 21, 2018

Frequency of pings homes in on lost jet

Detailed analysis of hourly "pings" to and from a stationary satellite positioned over the central Indian Ocean has led authorities to conclude definitively that Malaysia Airlines Flight 370 must have gone down in the southern part of the ocean.

Days after the plane disappeared, analysts at satellite provider Inmarsat used the precise time delay during transmission of those pings to calculate how far the plane was from the satellite, defining two vast circular arcs sweeping across south-central Asia and the Indian Ocean.

Now, an analysis of the shifting frequency of the signals — in the way the sound of a police siren changes as it comes toward you, then speeds away — and comparisons with signals from other planes in the region at the time has allowed the analysts to discount the northern arc and to zero in on a more defined final known position in the southern Indian Ocean, west of Australia.

Tim Farrar, president of TMF Associates, a Menlo Park, Calif.-based satellite consulting company, said further analysis of the satellite signals could help narrow the search area.

It could also help determine whether the plane was traveling for the last part of its journey in a straight line at a constant speed, with no apparent pilot intervention.

If so, that would raise the possibility that the plane was on autopilot before plunging into the ocean, with the pilots — and perhaps the passengers — incapacitated, possibly already dead.

Airliners use a satellite connection while out of radio range over the ocean for voice communication with the pilots and also to carry text messages to the airline operations base via the jet's data-communications link, the Aircraft Communications Addressing and Reporting System, or ACARS.

ACARS sent its last transmission a half-hour after takeoff. The last radio contact with the plane was 38 minutes into the flight; the jet dropped off radar screens minutes later. Even if ACARS was either turned off by someone or ceased functioning because of some system failure, the satellite connection remained.

Just as a cellphone communicates with cell towers so that the network can reach it with an incoming call, the Inmarsat satellite sends an hourly message to the terminal on board the airplane to check that it is still connected.

In response, the terminal sends back a ping to say, yes, it's still there.

The final ping from Flight 370 was sent at 8:11 a.m. local time, 7½ hours after the jet took off from Kuala Lumpur.

The pings identified the airplane as Flight 370 but contained no direct location data.

Nevertheless, Farrar, who said he spoke with both Inmarsat and the designers of the satellite equipment on the airplane, explained how it's possible to use the raw ping data to deduce location information.

The time the response ping takes to travel from the plane to the satellite hovering 23,000 miles above the Indian Ocean varies according to the distance the signal must traverse.

The satellite recorded at what point in the predetermined transmission time slot the ping from Flight 370 arrived, and so established how far away the jet was.

It was this data that convinced the Malaysian authorities, a week after the plane disappeared, to reorient the search toward two arcs in a large radius around the satellite.

Comments
There’s a new ‘Bachelorette’ contestant from St. Petersburg

There’s a new ‘Bachelorette’ contestant from St. Petersburg

  When ABC’s reality dating competition The Bachelorette returns next week, the pool of 28 contestants vying for love and roses from Becca Kufrin will include a fitness trainer who lives in St. Petersburg. Here’s what we know about 25-y...
Updated: 3 minutes ago
State softball: Academy at the Lake romps in long-awaited semifinal

State softball: Academy at the Lake romps in long-awaited semifinal

VERO BEACH — On a day when the weather at the state softball tournament finally said yes, Academy at the Lakes pitcher Alexis Kilfoyl said no to Lake Worth Christian.The hard-throwing right-hander fired a no-hitter in a Class 2A semifinal Monday morn...
Updated: 10 minutes ago
Editorial: Work on the broad areas where Americans, those who own guns and those who don’t, agree

Editorial: Work on the broad areas where Americans, those who own guns and those who don’t, agree

e_SSLqThe worst school shooting since ... February." The sentence jumps off the page of a news story in the aftermath of the murder of eight students and two teachers at Santa Fe High School in Texas. It has been only three months since a gunman kill...
Updated: 23 minutes ago
GasBuddy predicts plunge in summer travel, blames gas prices

GasBuddy predicts plunge in summer travel, blames gas prices

At least one gas price tracker expects rising fuel prices to sharply curtail summer travel. In a recent survey by GasBuddy.com, just 58 percent of motorists surveyed said they would take a road trip this summer, down 24 percent from last year. Just u...
Updated: 25 minutes ago
Former Admiral Farragut star Craig Watts leaves USF

Former Admiral Farragut star Craig Watts leaves USF

Bulls redshirt sophomore DB Craig Watts Jr., who practiced behind starting nickel back Ronnie Hoggins this past spring, has transferred to Division II Valdosta State, his father confirmed Monday.Watts, deemed a four-star prospect by at least four maj...
Updated: 26 minutes ago
Florida Department of Education prepares rules to govern scholarships for bullied students

Florida Department of Education prepares rules to govern scholarships for bullied students

Families of children who have been bullied or harassed in a Florida public school soon will have access to state scholarships to attend private schools instead.But first, the State Board of Education must set the rules for how the controversial "Hope...
Updated: 1 hour ago
Bill Nelson gets national help in the battle for Florida’s airwaves

Bill Nelson gets national help in the battle for Florida’s airwaves

Buried so far in TV ads from Gov. Rick Scott, Sen. Bill Nelson is finally getting some help.Senate Majority PAC said Monday it will spend $2.2 million on an ad in multiple markets across Florida. It's a bio piece that begins, "He served his coun...
Updated: 1 hour ago
Here are some of Harry and Meghan’s official wedding photos

Here are some of Harry and Meghan’s official wedding photos

LONDON — Kensington Palace has released three official wedding photographs taken of Prince Harry and the former Meghan Markle shortly after their wedding.Alexi Lubomirski's images include a family portrait of the couple with Queen Elizabeth II,...
Updated: 1 hour ago
Construction poised to begin this week on four-story boutique hotel in Ybor City

Construction poised to begin this week on four-story boutique hotel in Ybor City

TAMPA — A ceremony marking the start of construction on a four-story, $32 million boutique hotel at 1402 E Seventh Avenue has been set for Thursday.The site is now a parking lot, but plans on file with the city of Tampa outline a hotel project with 1...
Updated: 1 hour ago
What’s next for the Rays’ new pitching strategy

What’s next for the Rays’ new pitching strategy

ST. PETERSBURG — When Kevin Cash called team president Matt Silverman Sunday morning to wish him happy birthday, he expected to get back some form of an "attaboy" for implementing the Rays' latest unorthodox pitching strategy in using reliever ...
Updated: 1 hour ago