For the third time in five months, an unusual incident has taken place with President Clinton’s plane, Air Force One. The Boeing 727 jet disappeared from radar screens twice on the morning of June 5 while on a flight from Washington, DC to Boston, where Clinton was to give the commencement address at MIT.

Both incidents took place at the Federal Aviation Administration’s radar center in Gibbsboro, New Jersey, about 15 miles southeast of Philadelphia, which tracks most flights in the busy New York-Philadelphia corridor. The numbers and letters marking the position of Air Force One vanished from the screen for 24 seconds. Six minutes later, they vanished again for 36 more seconds. The air traffic controller monitoring the flight, who was stationed on Long Island, was in voice contact with Air Force One during both blackouts.

Two days afterwards a similar incident took place with Air Force Two, the government plane used by Vice President Albert Gore. It too disappeared from the radar screen at Gibbsboro for 24 seconds on a flight from New York City to Washington.

The FAA said it was investigating the cause of these incidents. The Gibbsboro radar had previously lost track of Air Force One on March 10. Six weeks before that, Clinton’s jet came within 2.36 miles of a US Airways plane heading into Washington’s National Airport. Air Force One was taking off from Andrews Air Force Base, a few miles away across the Potomac River.

Under any circumstances such incidents, involving the chief executive of the United States, would appear virtually inexplicable. The US radar system is the most advanced in the world. Throughout the Cold War decades, the US Strategic Air Command closely monitored all movements in or near US air space, and kept dozens of nuclear-armed warplanes continuously in the air, ready for hair trigger retaliation against a potential intruder.

Given the ongoing campaign to subvert and oust the Clinton administration through the operations of Independent Counsel Kenneth Starr, any anomaly involving presidential security takes on additional significance. It is worth recalling that only a few months after Clinton took office, Republican Senator Jesse Helms, a key ally of Starr, warned the commander in chief that he should avoid visiting US bases in North Carolina because there was so much hostility to him in the military that his safety could not be guaranteed.