More than 5,000 flights may be in the sky at once on the busiest holiday travel days.
The aircraft operating these flights navigate intersecting airborne highways, so it's quite normal to peek out your window and witness another aircraft passing by. Passengers often ask me if pilots are aware of other nearby aircraft while in flight, and whether they ever come "too close for comfort." The answers, in order, are yes and rarely.
Pilots have many tools at their disposal that clearly paint a picture of their surroundings. Today's modern commercial aircraft are equipped with traffic avoidance systems that show the position of other aircraft. Pilots can determine from a display if nearby aircraft are above or below them, as well as if they are climbing or descending.
If the system determines that a nearby aircraft is on a collision course, the pilots will be alerted. The alert will even go as far as to direct the pilots to climb or descend their aircraft to avoid a collision. Considering the many thousands of flights each day, it is very uncommon for such a drastic step to be required.
The primary responsibility for maintaining safe aircraft separation rests on the shoulders of air traffic control, or ATC, which uses an extensive radar network that allows controllers to keep close tabs on the position of each aircraft in the sky.
Controllers keep commercial aircraft horizontally spaced by miles, and vertically spaced by a minimum of 1,000 feet. ATC has its own warning system that tracks potential conflicts of aircraft coming too close to one another. If necessary, it will provide instructions to pilots to help maneuver their aircraft out of harm's way. Such situations are normally detected well in advance, and again, happen rarely.
While air traffic controllers keep airliners safely spaced in the sky, the safety of aircraft separation begins on the ground, when flights are planned. Rather than flying randomly all over the sky, commercial flights follow published airborne highways that are defined by latitude/longitude coordinates.
With permission from ATC, aircraft may deviate from these highways to fly more directly to a destination, or to avoid weather. Altitudes are not assigned at random either. Commercial flights headed east fly at odd-numbered altitudes, such as 35,000 or 37,000 feet, while westbound flights fly at even-numbered altitudes, such as 34,000, or 36,000 feet.
When traffic congestion is high, the need to keep flights at a safe distance from one another can lead to delays. Foul weather only worsens the problem, as storms can block valuable airspace.
Delays such as these will often be communicated by the airline as an "air traffic control delay." The best way to avoid delays is to avoid peak travel hours at major airports. Opt for early morning flights. Most airlines have apps that allow passengers to keep tabs on the status of their flight while on the go.
On behalf of the thousands of professional airline pilots nationwide, rest assured that getting you home safely is our priority year-round.