Navy officials said the plane was being towed out of a hangar in February when it clipped the structure.

The Navy's "doomsday" plane wasn't supposed to be on the ground in Maryland for long. Instead, the E-6B Mercury - a flying communications and command post designed to play a critical role during a nuclear war - should have briefly touched down before taking off again.

But as the hulking aircraft was attempting to perform the maneuver earlier this month at the Patuxent River Naval Air Station, about 60 miles southeast, things didn't quite go according to plan.

A wayward bird struck one of the plane's four engines when it was landing on Oct. 2, temporarily grounding it and causing at least $2 million in damage, Tim Boulay, communications director for the Naval Air Warfare Center Aircraft Division, told The Washington Post in an email Thursday. The incident was classified by the Naval Safety Center as a "class A" mishap, which also applies to cases that result in aircraft destruction, death or permanent disability.

At the time of the costly bird encounter, a team of people were on board conducting a systems test, but no one was injured, Boulay said. It is unclear what species of feathered creature collided with the $141.7 million plane, and the incident remains under investigation. As of Thursday, Boulay said the damaged engine had been replaced and the aircraft was back in service.

The bird strike comes just months after another E-6B Mercury sustained millions in damage at Tinker Air Force Base in Oklahoma, the Navy Times reported. Navy officials said the plane was being towed out of a hangar in February when it clipped the structure.

E-6B Mercury planes are a critical component of the Navy's "Take Charge and Move Out" (TACAMO) mission. Derived from Boeing's commercial 707 jet, the aircraft connects U.S. leaders to an arsenal of nuclear warheads ready to be delivered from land, air and sea in times of crisis, according to a Navy fact sheet. Until 1991, variations of the plane were kept in the air nonstop for three decades, providing a 24-hour link between the president and nuclear submarines during the Cold War, according to The Post.

The E-6B Mercury was accepted by the Navy in 1997 and deployed about a year later. The planes are just over 150 feet long and roughly 42 feet high. They can travel at 600 mph and have a range of 6,600 nautical miles.

Like every other plane, however, the E-6B Mercury does not come equipped with a foolproof defense against birds.

Between 1981 and 2011, naval aviators reported more than 16,500 bird strikes that cost $372 million in damage, according to the Naval Safety Center. But when the scope is broadened to include all military and civil aircraft, the number of cases increases exponentially.

Every year, there are at least 3,000 reports of wildlife strikes involving military aircraft, according to the Department of Defense Partners in Flight program. The Federal Aviation Administration reports an additional 2,300 encounters. This year marks the 10th anniversary of the "Miracle on the Hudson," one of the most infamous bird strike cases. In 2009, a commercial flight from New York's LaGuardia Airport to Charlotte, North Carolina, collided with a flock of geese shortly after takeoff, and both the plane's engines were taken out. All 155 passengers on board the US Airways flight survived after the pilot, Chesley "Sully" Sullenberger, successfully landed the jet in the Hudson River.

"Because pilots and crews use the same low altitude airspace as large concentrations of birds, the prevention of bird strikes is of serious concern to the military," according to the Defense Department.

The military has tried to reduce the "unpreventable risk" of bird strikes by modifying habitats and scaring birds away from runways and by studying bird movements near training routes.

At least five bird strikes in the last decade have been described by the Navy as "class A" mishaps, the Navy Times reported. The Oct. 2 incident is the second involving an E-6B Mercury plane.