Why is tracking a missing commercial aircraft so difficult?

Tracking an aircraft is not difficult from a technological point of view. The difficulties arise from the logistics of creating a system that can operate in all the various geographic regions of the world, all the different political or cultural regions of the world, and encompass all the different manufacturers of aircraft and reporting systems, etc.

The most reliable system is radar reporting. It works quite well in most parts of the developed world, especially if one country or organization accepts responsibility and sets the standards that all users must comply with. Radar comes in two flavors; primary and secondary radar, primary radar is what the military relies upon because it “sees” the aircraft regardless of any action the pilots may, or may not, take. The downfall of primary radar is that is just detects the aircraft in space, there is no way to tell who that is, or where they are going. We use secondary radar for air traffic control because it merges the capabilities of primary radar with banks of computers that listen for the transponder codes that airliners transmit. The transponder tells the secondary radar that “I’m BA100, a Boeing 747, en-route from London to New York, at 37,000 feet”. Most of the time radar is either primary or secondary, not both, although there are exceptions. (On a side note, prior to the 9/11 attacks the US was in the process of phasing out primary radars because ‘we didn’t need them any more’.) The biggest problem with radar is that it is limited to line-of-sight. That means it can only ‘see’ approximately 180 miles, give or take. Radar is also very expensive to install and maintain, and it takes a relatively sophisticated organization to take all the radar images from all the different antennas and create a coherent picture of the airspace in question. Hence, there is very little radar in the undeveloped parts of our planet.

Even if all the terrestrial regions of the world had the money and sophistication to run a radar network we still have a problem with all that water. Remember the 180 mile limitation of radar? From a technology point of view it would be easy to have all airliners determine their position with their on-board GPS system, and then transmit that position to a station that would record that stream of ‘position updates’ for real time position reporting. The difficulty is getting everyone on the planet to agree on the acceptable equipment so that it is all compatible, that includes the equipment on the aircraft, as well as the receiving stations, some of which must be satellite based. And who is going to store all that information, imagine every aircraft in the world reporting their 3 dimensional position once every minute? Who gets access to that position information? Who has control of the system?

Right now some countries use English as their air traffic control language, some use their native language; some countries measure altitude in feet, some use meters; some measure elevation relative to sea level, some use height above the ground; some measure speed in knots, some use miles per hour or meters per second. Many countries use GPS, but Russia, China, and the EU are developing their own Sat Nav because they don’t want to be reliant on the US based GPS system.

Remember how well radar works? But most of the terrestrial earth does not have radar coverage due to cost. So who is going to pay for all the hardware on the aircraft, all the new satellites, all the new ground stations, all the storage of all the data that has now become a deluge?

So you see it’s all rather easy. We just have to agree on who is going to pay for all the new hardware, who the manufacturers will be, who will set the international standards that the system will operate under, oh, and who gets to control the system that can see inside every country on earth and over every ocean.

Normal aircraft tracking

Air traffic control - standard international practice is to monitor airspace using two radar systems: primary and secondary.
Primary radar -based on the earliest form of radar developed in the 1930s, detects and measures the approximate position of aircraft using reflected radio signals. It does this whether or not the subject wants to be tracked. Secondary radar, which relies on targets being equipped with a transponder, also requests additional information from the aircraft - such as its identity and altitude.
All commercial aircraft are equipped with transponders (an abbreviation of “transmitter responder”), which automatically transmit a unique four-digit code when they receive a radio signal sent by radar.
The code gives the plane’s identity and radar stations go on to establish speed and direction by monitoring successive transmissions. This flight data is then relayed to air traffic controllers.
However, once an aircraft is more than 240km (150 miles) out to sea, radar coverage fades and air crew keep in touch with air traffic control and other aircraft using high-frequency radio.

THERE’S NO RADAR TRACKING AIRLINERS OVER THE OCEAN
It is a misconception that airline pilots are in constant communication with air traffic control, or that planes are constantly watched on radar. Once a plane is more than 100 or 150 miles from shore, radar no longer works. It simply doesn’t have the range. (The specific distance from shore varies with the type of radar, the weather, and other factors.) At that point, civilian aircraft communicate largely by high-frequency radio. The flight crew checks in at fixed “reporting points” along the way, providing the plane’s position, air speed, and altitude. It isn’t uncommon to maintain radio silence between reporting points because cruising at 35,000 feet is typically uneventful. Some aircraft communication systems don’t require pilots call in; flight management computers transmit the info via satellite link.

Although modern flight management systems use GPS for navigation, that only tells the airplane where it is–it does not tell air traffic control where the plane is. It’s a bit like taking your iPhone into the heart of the Mojave desert: Your GPS will tell you where you are, but you can’t use Find My Phone because there’s no cell coverage. Although it would be possible to stream data from an aircraft in real time via satellite, implementing such a system across the industry would cost billions of dollars, Smith said.

The simple hard truth is it’s very difficult to find things in the water,” said retired Col. J. Joseph, a former Marine Corps pilot and aviation consultant.

The most chilling thing about this is the fact the plane seemingly vanished without a trace. The captain, who had more than 18,000 hours of flight time, gave no warning, issued no mayday. There was no indication anything was amiss. This is not terribly unusual, because a flight crew’s first priority in an emergency is dealing with the situation at hand. “Aviate, navigate, then communicate” is the mantra. Airline pilot and blogger Patrick Smith says the radio silence “doesn’t startle me.”

“It’s actually uncommon for there to be a distress message,” he said. “It goes one of two ways. The first is something happens so catastrophically and so suddenly that there wasn’t time for it. Secondly, crews are trained so that communicating with the ground is secondary to dealing with whatever urgency is at hand.”