A United Airlines pilot flushed bullets down a toilet onboard a flight from Houston to Germany last month after realizing that he brought live ammunition on the aircraft.

United spokeswoman Karen May noted Thursday that the pilot shouldn't have thrown the bullets in the toilet. An investigation is now underway and the pilot's status is unknown, according to Fox News.

Under a post-9/11 federal program, a pilot is only allowed to carry weapons in the United States.

"Under the Federal Flight Deck Officer programme, eligible flight crew members are authorized by the Transportation Security Administration to use firearms to defend against an act of criminal violence or air piracy attempting to gain control of an aircraft," said the TSA, according to the Economic TImes.

When the pilot realized his mistake, he tried to throw out the bullets in a trash can, but a passenger noticed them and became concerned. The passenger then reported it to a flight attendant who, in turn, told the captain. That's when the captain flushed the ammunition down the toilet, a source told CNN.

After landing in Munich, where gun laws are particularly strict, German authorities retrieved the bullets from the plane.

While he didn't handle the situation properly, it's unclear if the pilot will face criminal charges, reported the Aviation Herald.