(Image credit: Sergio Dionisio/Getty Images)

Was the black sludge that reportedly  fell on Artie Hughes and his wife as they sat on their porch in Malverne, N.Y., human waste from the plane passing above them? It's possible. And it wouldn't be the first time  people on the ground got pelted by what they suspected was airline waste.

Hughes told radio station  1010 WINS  that he initially thought the black, oily substance was fuel or hydraulic fluid, but the police officer who responded to the Hughes' call suspected lavatory runoff. After the officer made several phone calls,  he told Hughes there had been an "incident" and lavatory excrement had leaked out.

The Federal Aviation Administration will begin an investigation into the incident on Monday, Newsday reports. FAA spokeswoman Kathleen Bergen told the Long Island newspaper, "This is very rare. More often we get reports of 'blue ice' falling in people's backyards" from airplane lavatory holding tanks.  "Blue ice" is a euphemism for sewage treated with a blue liquid that freezes and  can  unintentionally be dispensed midflight.

The FAA, however, said on its  website that "blue ice" would melt long before it hit the ground.