Recent reports in the mainstream media raised questions about whether FAA's NextGen air traffic control system might be vulnerable to hackers who can create "ghost airplanes," and also asked why 102 "zombie towers" across the country are kept open all night despite low traffic. The FAA has said that airports with four or fewer flights per hour at night don't need to keep the tower open, according to Bloomberg News, yet about 100 towers are staffed that fall within those guidelines, costing about $10 million per year. Meanwhile, an NBC affiliate in California's San Francisco Bay area reported that hackers say they could insert fake "ghost" airplanes into the ADS-B system and controllers would be unable to tell them from real aircraft.
FAA spokesman Ian Gregor told NBC Bay Area the agency has "a thorough process in place to ensure the safety and security of the ADS-B system." Potential vulnerabilities are assessed on an ongoing basis, he said. "We require continual, independent validation of the accuracy and reliability of ADS-B and aircraft avionics signals. The air traffic system is based on redundancies to ensure safe and secure operations." As for the "zombie" towers, Bloomberg said "members of Congress from both parties" have blocked attempts to reduce hours or merge facilities.