Have you ever thought about how airplanes manage to avoid each other in the sky? It might seem like there is plenty of room up there, but with up to 5,000 flights in the air over the U.S. at any given moment, the sky can be a very crowded place.
Who are the people responsible for ensuring the safety of 64 million take-offs and landings in America every year? Where do they work and just how close can planes fly to each other without crashing? It's a complicated juggling act involving thousands of staff at hundreds of control centers keeping 87,000 flights and all of their passengers and crew, safe every day.
The FAA (Federal Aviation Administration) is the government body responsible for your safety in the air and on the ground at airports. From the construction of safe airports, to pilot licensing, the FAA is in charge of every aspect of civil aviation including the people who direct the planes.
Highly-trained air traffic controllers need a three-year college degree, a high enough score on the FAA pre-employment test, and a pass on the eight hour Air Traffic Standardized Aptitude Test just to get to the FAA Academy. Five months at the FAA Academy and then up to eight years on-the-job training later they become certified as an air traffic controller.
Once a plane is in the air, they may be handed off from an airport control tower to controllers in en route facilities. There is a total of 21 en route FAA locations across the U.S., and they control air traffic flying through large sections of airspace at high altitudes.
The action doesn't happen in the air, though. Flight safety begins before an aircraft ever even leaves the ground. Air traffic controllers guide planes around the airport so they can move safely between the gates and the runway.
The staff in the control tower must also coordinate support vehicles such as baggage trucks and refueling vehicles to protect aircraft from small accidents on the ground that are potentially catastrophic in the air.
Pilotage is navigation by reference to visible ground landmarks, such as buildings, shorelines, rivers, mountains, etc.
Both airport and en route control towers use advanced radar systems to provide an overview of the traffic in their airspace.
On top of the staff and technology in control towers, every commercial aircraft is fitted with a Traffic Collision Avoidance System (TCAS). These systems monitor the air space directly around an airplane. If the system detects another plane that is too close, it alerts the pilot and the control tower.
How close is too close? An aircraft must be separated by at least 1,000 vertical feet if the staff is relying on radar. Their vertical mileage may also change distances, but this can vary by a number of factors.
If visibility is clear, controllers can use Visual Flight Rules. These allow controllers to bring aircraft within 500 feet of each other, but they must also consider airspeed and wake turbulence.
To assist the air traffic controllers, airplanes are fitted with transponders. These devices detect incoming radar signals. Once an incoming communication is detected the transponder broadcast an amplified radio signal back. This contains information about the plane such as its altitude, speed, flight number, and destination.
The process of calculating one's position, especially at sea, by estimating the direction and distance traveled rather than by using landmarks or astronomical observations.
This form of navigation is used only by larger airplanes due to the cost of the equipment. Three sensitive gyroscopes measure changes in velocity in the three directions, and these changes are used to deduce the aircraft's position.
Through radio navigation, airplanes can navigate using ground-based radio transmitters to calculate their position. This works even when the weather is too poor to see the ground.
The GPS (Global Positioning System) is a 'constellation' of approximately 30 well-spaced satellites that orbit the Earth and make it possible for people with ground receivers to pinpoint their geographic location. The location accuracy is anywhere from 100 to 10 meters for most equipment.
Ultimately, the airplane's journey through the sky is controlled by a combination of highly-trained staff and advanced technology working together to keep you safe.
Updated by: Richa Chawla