Aviation industry officials doubt that raw sewage dumped on a Taylorsville home last week came from a commercial airliner.
Federal Aviation Administration spokesman Mitch Barker said such material, if leaked from a plane, would likely be frozen because aircraft fly at high altitudes. But the sewage dumped on the Taylorsville home, and which splashed five other homes, had not been frozen.Barker said commercial U.S. airlines are required to use a blue disinfectant in sewage-holding tanks. The material deposited over the Taylorsville house had no trace of blue.
The FAA is continuing to investigate, he said.
"Our investigator will use radar tapes that we can roll back to determine what aircraft were in the area at the time." In addition, investigators will examine private and corporate planes at Salt Lake City Airport No. 2 in West Jordan.
"There is a remote possibility that a foreign-registered plane, which is not required to use blue disinfectant, was in the area," he said.
Barker said that when tanks on airliners leak, blue ice forms along the aircraft's outer skin, and when the plane comes in for a landing, the vibration can cause chunks of ice to fall off.
He said a valve can break in the system, but frozen blue disinfectant would seep out over a long distance, not drop like a water balloon.
Barker and other aviation officials said airliners do not and cannot dump waste while flying.
There is no control button or lever in the cabin that the pilot can push or pull to release sewage, said Mary Jean Olsen, spokeswoman for Boeing. "The captain can drop fuel (in a landing emergency), but cannot drop waste."
When a blue-ice incident occurs, the only substance involved is the disinfectant itself, not waste material, said Bob Kelley-Wickemeyer, chief engineer of aerodynamics for Seattle-based Boeing Commercial Airplanes Group.
"For an aircraft in the air, I cannot visualize how you can dump (sewage). The control to the valve is only available outside the airplane. Unless Superman was flying alongside the airplane and opened the (tank) door, it just can't happen," he said.
The waste goes from the lavatory into a holding tank, and then is pumped into trucks as part of regular servicing, said Tracy O'Donnal, Atlanta-based spokesman for Delta Air Lines. "All our systems are closed systems; we do not dump in flight."