Opinion / From the Readers

MH370 and analysis of ping data

(China Daily) Updated: 2014-05-14 08:18

It was recently reported that all the information gathered on the disappearance of the Malaysia Airline Flight 370 would be reviewed to make sure that the search is being conducted in the right area.

Ping data analysis has played a pivotal role in mapping out the "most likely" search area. Critical to the accuracy of the ping data analysis is accurate knowledge of the circuit latency of the pinging device on the missing aircraft. Each millisecond of uncertainty in the circuit latency translates into 150 kilometers of uncertainty of the location of the pinging source from the satellite. And since the satellite is 36,000 km above the earth, this translates into 3,300 km in uncertainty in its position on Earth, which is more than half the distance from Malaysia to Africa.

To put this in context, in test pings from router to an iPhone on a local wireless network, this same device has a ping response ranging typically from 27 milliseconds to 30 milliseconds. How accurately can then one know the latency of a device to which no one has access? A similar uncertainty of only 3 milliseconds translates into an uncertainty in position of 10,000 km on the surface of the globe.

PAUL POWER, Australia, via e-mail

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