Controllers lost contact on May 1 because a temporary control tower antenna had not been set up at the correct location, Brig. Gen. Matthew Braman told AP.
The ADSB safety system has become a flashpoint as some have pointed to its likely lack of use by the helicopter as a potential cause of the Jan. 29 crash.
Without evidence, Trump blamed air traffic controllers, the helicopter pilots and Democratic policies at federal agencies for Wednesday night's collision.