What are the airways?

  In the air between the airports are airways, or roads, through the sky along which the planes travel. Because of the many planes flying overhead, both during the day and night, it is necessary to set up rules for the road just as we have traffic rules for the cars on the streets.
  Except when taking off or landing, airplanes must fly at least 500 feet above the ground. Over cities and other
congested areas, the planes often have to fly 1,000 or even 2,000 feet above the ground.
  The route a plane takes is determined by the FAA which controls all air traffic. At major airports, there are men sitting before air maps, radios and con¬trol boards, and they keep track of every plane as it plows through the skies.
  Specific airways have been established to prevent planes from colliding in the air. All eastbound flights — planes flying from west to east — fly at oda thousand-foot levels, plus 500 feet, above sea level. Thus, a plane flying from Los Angeles to New York could fly at 15,500 feet. Westbound flights, on the other hand, fly at even thousand-foot levels, plus 500 feet, above sea level