Air travel used to be the dream of mankind, but today it’s a pretty standard part of our reality. Now with all those jets zipping around, the sky is a lot more crowded than it was in 1903 when it was just one guy up there named Orville. How do we share the skies safely?
It’s getting mighty crowded in our skies, look up right now, I bet you’ll see an airplane. Or your ceiling. But above that…an airplane. So, how do we make sure we have enough space up there to stretch our wings? To keep the skies safe there needs to be an interplay between regulations and technology. I won’t get too into it, but suffice it to say, there are a lot of rules aircraft have to obey, both in flight and before take off. To start with, they need to file a flight plan with information like departure and arrival points, estimated flight time, alternate destinations in case of emergency, passengers on board, and info about the aircraft itself.
Then, air traffic controllers will take that flight plan into consideration with other flight plans, and run it through a computer algorithm, which helps determine the fastest and safest route to take. At a minimum, flight paths are kept 1000 feet (305 meters) from each other, because c’mon you don’t want to get too close — your pilot is good but he’s not Maverick. Unless his name is Maverick. And then he is. Once it’s time to kick the tires and light the fires, the airspace itself is divided into different classes based on altitude and proximity to airports. Obviously, airspace near larger airports is going to be the busiest, so it has the most rules. On top of that it also has the most failsafes for tracking incoming and outgoing aircraft to make sure nobody’s swapping paint, like radar.
Radar is actually an acronym that stands for RAdio Detection And Ranging. It works by sending out radio waves that bounce off of objects and come back to a receiver. Based on the time delay between sending and receiving transmissions, it’s possible to calculate where an object is. And based on how much of the signal gets returned, an object’s size can be determined. This is why stealth aircraft are shaped the way they are: they’re scattering the radio waves away from the receiver. But radar doesn’t work on every kind of object, it usually works best with metal, but not all planes are made that way; smaller composite planes just don’t show up. The radar typically used for commercial air travel also has a limited range over the ocean, extending about 200 miles (321 kilometers) off the coast. Plus radar can’t tell air traffic control an object’s altitude, which is a pretty important consideration when you’re moving in 3 dimensions. To overcome these problems, a Secondary Surveillance Radar system is used. Commercial aircraft and many smaller private planes are equipped with a device called a transponder.
The device is so important, commercial aircraft actually carry two. Air traffic control’s radar pings the transponder with a request for information with a regular radio signal — the pings can teach Air Traffic Control a lot, but even more importantly, transponders are hooked into the aircraft’s on-board systems. So, the altimeter can relay its information to the ground. Pilots are also given a code by air traffic control which the plug into their transponder to make sure they correlate this information with their flight plan. Transponders can even be used so aircraft can communicate with each other, which is handy over the ocean and out of range of Air Traffic Control’s eyes.
Commercial jets don’t have radar for detecting other aircraft, but they can detect each other’s transponders and calculate if they’re on an unsafe course. If they are, the aircraft will alert the pilots and suggest a course correction. They can even coordinate the two planes’ adjustments, avoiding both of them doing that awkward dance we all do when walking towards someone in a hallway. Communication technology keeps aircraft a safe distance from each other, but newer materials make aircraft stronger and more comfortable.