Marine One departs the White House in Washington, D.C., on May 12. The aircraft had difficulty making contact with air traffic control at Ronald Reagan National Airport on Thursday. File Photo by Bonnie Cash/UPI | License Photo

Aug. 28 (UPI) -- The pilots of President Donald Trump's Marine One helicopter and air traffic controllers at Ronald Reagan National Airport had difficulties communicating with each other, the second such incident in a month.

Air traffic control audio reviewed by CNN said the incident happened Thursday as the helicopter neared departure from the White House. CBS News reported that the pilots' calls to air traffic control went unheard and another pilot intervened.

The incident comes less than a month after there was a "loss of separation incident" between Marine One and a commercial aircraft departing Reagan airport on Aug. 4. Air traffic control didn't receive the call from Marine One that it was departing the ellipse so it didn't halt departing commercial flights as typical during Marine One movement. It led to the helicopter coming within 700 feet vertically of an Envoy Air jet.

Trump was aboard the helicopter during that safety incident, the National Transportation Safety Board said. He was en route to Joint Base Andrews in Maryland where he was due to board Air Force One for a trip to Los Angeles.