‘NextGen’ Tracking Would Mean No Plane Could Disappear. 
So Why Aren’t We Using It?

Malaysia Airlines Flight 370
A Japan Coast Guard officer studies a map in the search for the missing Malaysia Airlines MH370 plane Edgar Su/Reuters

The story of Malaysia Airlines Flight 370 leaves many unanswered questions in its trail, not least the enduring issue of passenger safety in the future. How can we be sure that similar scenarios will not happen again, and that other passenger jets will not simply disappear from the face of the earth in spite of the supremely sophisticated equipment that is supposed to be monitoring them?

In the United States, some airlines and engineers think they have the answer. They are heralding the advent of a new satellite-based guidance and tracking system, NextGen (Next Generation Air Transportation System), which they hope will be more efficient and accurate than the systems on which Flight 370 depended. The era of the passenger jet, they say, will then begin in earnest.

NextGen, which is already being rolled out across the U.S., has the potential to transform the movement of air traffic and bring it into the contemporary age. The idea is that GPS will provide highly detailed, real-time information that will cut distances, journey times and carbon emissions because pilots will follow the smartest, shortest routes, like car drivers using sat nav. Its sponsors say that by 2025, when NextGen is scheduled to be fully implemented in the U.S., pilots and controllers will have a much clearer idea of where other aircraft are in the skies, hugely reducing the scope for accidents.

This would certainly be a huge step forward. That’s because today, tracking and guiding even the most up-to-date aircraft—including warplanes on vital missions or fully laden passenger jets like Flight 370—ultimately depend on technology that has some glaring weaknesses.

To track flight paths, air traffic controllers currently rely not on satellites but on something relatively old-fashioned: radar. First pioneered in the late 19th century and deployed as cutting-edge technology as long ago as the Second World War, radar suffers from clear limitations and blind spots.

Most obviously, radar can only indicate the presence of a plane in the sky but not reveal which particular plane it is. By the time it vanished, Flight 370 was traveling within the range of land-based radar, but the Malaysian authorities could not be sure which plane they had detected, speculating only that the jet may have “changed course.”

Identifying a plane is much harder if it moves, even briefly, into one of the two blind spots from which radar suffers: range and altitude. If a plane dips below an altitude of 5,000 feet—or beyond the range of the land-based “primary” radar, which is usually about a hundred miles or so from a coastline—controllers can’t pinpoint its whereabouts alone. Instead, they depend on the cooperation of the pilots.

When they move through these radar blind spots, pilots use a transponder (a “transmitter-responder”) to signal their exact location, beaming this information to radar or satellites, or by voice traffic, high-frequency radio or data similar to text messaging. So before it vanished, Flight 370 was in regular touch with Flightradar 24, a global tracking system for commercial aircraft that has a number of beacons along the Malaysian coast. When it transmitted its last signal to Flightradar, not long after 1 a.m., the Malaysian jet was cruising at a height of about 35,000 feet.

To determine the location of any aircraft once it moves beyond the range of “primary” radar, controllers depend heavily upon these transponder signals. So a plane could, in theory at least, “disappear” if it moves below 5,000 feet, or beyond a hundred or so miles from the coast, and if, for whatever reason, its transponder stops working. A transponder is likely to stop working only if its electrical supply develops a sudden fault, if the pilot switches it off (perhaps when forced to do so by hijackers), or if a single, catastrophic event, such as a midair collision or explosion, destroys it.

NextGen is supposed to eliminate any chances of error because of the accuracy of the satellites it uses. But it is not, however, quite the miraculous development for civilian safety that it may sound like. In fact, it is likely to create as many challenges as it solves, assuming that it delivers on its promises at all.

Anyone who has used a sat nav system in the car will know that not all of the routes it outlines are the best ones. Occasionally, a suggested route is completely inappropriate. In the same way, the NextGen system could prove vulnerable to hacking, viruses and cyberwarfare.

Any technical faults would have catastrophic consequences, because the system is designed to encourage more air traffic in the skies. The argument is that there will be a considerable increase in consumer demand for jet travel, because the skies will be safer and flights quicker and cheaper. In other words, any glitch in such congested skies would be akin to a motorway pileup on an incomparable scale.

There is another reason why any such midair accidents will prove calamitous. Satellites will redirect air traffic along new routes that may reduce journey time but will take them over more residential areas than before. This is already happening in parts of New York that lie directly beneath NextGen’s first tried-and-tested routes, with jets taken to and from LaGuardia Airport. This new flight path has deeply unsettled the residents of a once quiet area whose tranquillity has been shattered, just as sat nav affected some towns and villages, redirecting traffic along some quiet roads and lanes. But such extra noise, carbon and pollution is next to nothing compared with the fallout from a midair collision directly overhead.

All of this assumes that the program will get off the ground at all; it requires huge investment, time and planning. Skeptics point out that it is already 10 or more years behind schedule and will cost perhaps three times the $40 billion estimate. Even then, it will be far longer before such advanced and supremely expensive systems become widely used in Europe and beyond.

If NextGen does take off, tomorrow’s passenger jets may not be able to disappear in the same manner as Flight 370. But that, unfortunately, will not make any of us safer.