It's been 10 months since Malaysia Airlines flight 370 disappeared. Despite search efforts that stretched from the South China Sea to the Indian Ocean, the plane remains lost.

    Even in the shallow water of the Java Sea, officials took several days to locate the remains of AirAsia flight 8501, about 160 kilometers off the coast of Borneo Island.

    With satellites and other technology available, how can large airplanes just disappear?

    Here is a little-known fact about flying: airplanes that are very far from land – crossing an ocean, for example – do not always appear on land radio systems and radar.
    以下是关于飞行的一项鲜为人知的事实:距离陆地很远的飞机 -- 例如穿越海洋的飞机 -- 并非一直出现在陆地无线电系统和雷达中,

    Satellite communication and navigation technology, such as the global positioning system (GPS) and satellite telephones, allow us to know planes' locations. But, the technology isn't always used.

    The reason is cost.

    Michael Braasch is an Ohio University professor of electrical engineering. He says the technology is expensive to use, and until recently, wasn't seen as necessary.
    迈克尔·布拉希(Michael Braasch)是俄亥俄大学的电气工程学教授。他说这种技术的应用非常昂贵。而直到最近也未被视为必须。

    "Being able to transmit messages through the satellite communication providers is an expense that, up until recently, there wasn't a great need for, being able to keep track of the aircraft second-by-second," Professor Braasch said.

    But after a bad year for airline safety, that may change. In 2014, the two plane crashes over water killed 401 passengers and crew members.

    Professor Braasch says after the Malaysia Airlines disaster last March, it became clear that something must be done. "We lost a wide-body airplane and we have no idea where it is, and, in this day and age, that's just absurd," he said.

    Pilots are required to inform air-traffic controllers of their current location during flights. But during emergency situations that require quick decision-making, pilots are not able to let air-traffic controllers know that information.

    In both crashes at sea, controllers lost communication with the aircrafts before the pilots reported any problem.

    The International Air Transport Association released a report last month on the topic. The report recommended that each airplane have an automated location-reporting system that works if pilots cannot report the plane's location.

    Professor Braasch says the technology for this already exists. But, he says, some airlines do not agree with the recommendations. He says they worry about the costs and the difficulty in agreeing to a standard system internationally.

    "It's mostly just the matter of dealing with the added expense and then putting a system in place that everybody agrees to the format and the standards and things of that nature," he said.

    Some pilots are also concerned about having an electrical system on board that could not be turned off in the event of a fire. Right now, only the flight data recorder, the so-called black box, is out of the pilot's control.

    For now, the United States and Europe are prepared to use a system called Automatic Dependent Surveillance Broadcast, or ADS-B. The system is designed to broadcast the airplane's location to air-traffic controllers and to other airplanes nearby.

    The system will be required for some aircraft in Europe by 2017 and in the United States by 2020.

    I'm Jonathan Evans.
    我是乔纳森·埃文斯(Jonathan Evans)。(51VOA.COM对本文翻译保留全部权利,未经授权请勿转载,违者必究!)