Thursday's hearing also revealed that the false alarms that told pilots they were on a collision course with another plane while on approach to Reagan Airport earlier this month were caused by the Secret Service and the Navy improperly testing counter-drone technology, according to an exchange between Cruz and Rocheleau. The testing was being done on the same spectrum that the Traffic Collision Avoidance System in the cockpit uses. Cruz said the Secret Service and the Navy were warned not to use the same spectrum before the false alarm incidents.