For at least two decades, pilots have complained about near misses with helicopters and other aircraft in the congested airspace above Reagan National Airport, according to an NBC 5 Investigates review of complaints lodged with NASA's Aviation Safety Reporting System. The complaints are not necessarily investigated or corroborated by the federal aviation authorities but do underscore concerns raised by the pilots themselves about airspace congestion at one of the nation's busiest commercial runways in DCA. NBC 5 Investigates found at least 16 complaints in NASA's Aviation Safety Reporting System dating back to 2006 where pilots referenced near misses with helicopters...