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Interference and flight safety

A View From the Edge

The one thing you really, really want the pilot to know is this: Where the heck are we?

In the mid-1980s, I was flying to Tokyo and had the opportunity to sit up front with the pilots for an hour. Halfway across the Pacific, the JAL pilot, a Swede, had one leg across the armrest and was chatting amiably about aviation matters. The co-pilot, a novice, was Japanese and had his seat forward, white-knuckled hands gripping the wheel, staring unmoving out the windscreen, eyes flicking the horizon.

The co-pilot asked, “Where are we?”

The pilot responded, “We’ll know soon enough when we pick up the Alaska beacon.”

What he meant was the homing signal emanating from the FAA radio transmitter near Anchorage, Alaska. Up until then, winging across the Pacific, at 35,000 feet, with 350 passengers aboard, the jumbo was dead reckoning — a sort of aviation equivalent of point it in a general direction and hope you are right.

Sure enough, about 10 minutes later, the Loran radio receiver picked up the radio signal from Alaska and told them they were 150 miles off course.

“Time to correct course,” said the pilot.

The co-pilot asked for a heading, was given one, and banked the plane. Seconds later the FAA air traffic control came on the cockpit speakers and said they were glad the plane was turning to correct back onto the filed flight plan. The pilot radioed back, “Roger that,” and went back to chatting with me.

Is it any wonder, then, that when GPS units began to be wired into flight cockpit controls that airlines were happier? Here was a device that received a handful of weak radio signals from space, thousands of miles above the earth, each satellite blipping coded information to each airplane receiver — and all that could be computed by the receiver to tell the plane exactly, to within 20 feet, where the heck they were.

The fuel saving, the passenger safety, the FAA air traffic control end of nightmare rogue planes, and, never least, the stress reduction for pilots was immense. By the mid-1990s every commercial plane had a GPS unit aboard.

However, there is one important thing to remember: No one trusted them on the ground. On the ground, taxiing at airports, eyes and radio control from the tall airport tower were considered safer.

Why? Because in the air, with radar making sure planes stay at least 1,000 feet away from each other, and onboard TCAS (collision warning devices), the 20 feet margin of accuracy of GPS was very safe. On the ground, 20 feet was deemed too darned close for comfort in a crowded airport.

That has now changed. With cutbacks at airports, cutbacks at the FAA for air traffic controllers (why did you think they were falling asleep? One man to do the job of previously three men) and increasingly busy airports, GPS has become the second line of defense against ground collision and traffic control’s newest tool on which to rely (to make further cutbacks).

So, let us turn to the passenger who is desperate to fire up his or her smart phone. Surely, one little phone cannot disrupt any of that GPS safety, can it? Well, yes it can and yes it does.

Even if your smart phone does not have GPS (they all do, but you can turn that off, sometimes, unless it is an iPhone), the talking frequencies that used to be for television have been sold to the phone companies. Heard of 3G and 4G? Those were old TV frequencies sold off to the highest phone company bidder.

The problem is, those frequencies are smack dab right up against the GPS frequencies, and little transmitters (your smart phone) are messy transmitting devices that spray and stray into the GPS frequency arena.

Want to know how a 747 can clip the tail of a smaller commuter plane? The GPS lost signal for a moment and the plane was misdirected for a few seconds off course. Bang! How did that happen? So far, all anyone knows is that “the GPS unit went off calibration for a few seconds.”

Sanjiv Ahuja is the chairman and CEO of LightSquared, a company building a huge space-based nationwide 4G high-speed wireless system. Over the next eight years, LightSquared will invest $14 billion in developing this network.

Sanjiv says his company’s wireless network can work with the GPS industry to find a solution to interference. Note that he says he can find a way, not that there is no problem already. He knows there is — a serious problem.

You see, each phone is a transmitter, which is his real worry. He can make his space satellite pinpoint accurate so as not to interfere with GPS, but he knows that ground units — your phone — are cheap, quickly made, frequency pigs. Well, they have to be, to be affordable. If your phone was a precision device it would double in price, at least. Those are the realities here.

So, next time you see someone switching on their phone in flight or just after landing, remember they have just put your life in jeopardy and do something about it. It does not just take a terrorist to bring down a plane; all it takes is one ignorant broadcaster sitting next to you while you do nothing.

Peter Riva, formerly of Amenia Union, lives in New Mexico.