Pilots and air traffic controllers agree that part of the problem is the woefully outdated and overloaded radio system that's supposed to keep planes out of each other's way. Third world nations have better air traffic control equipment than we do. For example, the radio can become jammed with pilots and controllers trying to send and receive instructions at the same time, leading to missed communications and potential disasters. Also contributing to the situation is that many airports are handling far more flights than they were designed for, while traffic controllers may be directing more than 50 planes at once across active runways. Pilots can be distracted while listening for crucial radio instructions from the tower, because, at the same time, they are often going through instrument checklists and studying maps.
Language barriers can also be responsible for runway incursions.
Though English is aviation's official language, pilots are not tested or certified. Even when pilots do understand the controller's instructions, it can be difficult to carry them out. Misleading and confusing surface markings and signage, combined with poor lighting, often leave pilots uncertain about where to taxi and where to stop. On a runway, merely crossing a double yellow line can threaten hundreds of lives. Almost 10 years ago, the FAA said reducing runway incursions was a top priority.