Air traffic controllers also still use slips of paper containing flight numbers to help track the approximately 45,000 flights that the Federal Aviation Administration handles on a daily basis.

President Trump’s nominee to lead the Federal Aviation Administration was grilled by senators Wednesday on critical safety-related issues, including the required hours needed for pilots, the outdated air traffic control system and the ongoing problems at Ronald Reagan Washington National Airport.

The Federal Aviation Administration is seeking contractors to modernize its decades-old computer systems within four years.