PHILADELPHIA — A key piece of hardware that aviation experts and pilots said could solve the mystery in the fatal crash of the medical transport Learjet on Jan. 31 turned out to be useless.

Jet Rescue Air Ambulance, a company based in Mexico, operated the Learjet 55, a medical jet that crashed in Northeast Philadelphia on January 31 at 6:30 pm local time. The plane which was on its ...

And while the doomed Learjet 55 was in contact with an air traffic control tower, "there were no distress calls received from the flight crew," the report said. The fiery crash killed six people ...