A Learjet 60 crashed near Palm Beach, Florida, on Sunday while flying from Texas to the Bahamas, killing all nine people aboard. Investigators have not established the cause, but are examining whether ice and storm conditions contributed to the accident.

The aircraft was flying at 35,000 feet when it entered a storm cell at about 12:48 p.m. The copilot, 20-year-old Nathalia Filgueiras, told Miami air traffic control that the plane was encountering light clear icing and moderate turbulence.

Experts say ice accumulating on the wings could have affected the aircraft’s aerodynamics and made it harder to control. The National Transportation Safety Board (NTSB) has said that as little as a quarter-inch of ice on a wing’s leading edge can lead to a sudden loss of control. Ice can also affect an aircraft’s engines, structure and flight instruments.

The Learjet 60 has three systems designed to counter ice: electric heaters on the leading edges of the wings and horizontal stabilizers, inflatable rubber boots that break up ice, and hot exhaust gases circulated over the wings. Investigators will examine whether the crew knew it was entering icing conditions and whether the protective systems were activated, according to Mike McCormick, a former FAA air traffic control director.

Former NTSB investigator Gregory A. Feith said the aircraft may have encountered clear ice, which can spread across a larger area of the plane. He also raised the possibility that an attempt to climb out of turbulence caused a sharp pitch change and a tailplane stall, a loss of lift on the horizontal stabilizer. These remain hypotheses, not confirmed findings.

Turbulence is another focus of the investigation. Filgueiras reported altitude changes of between 600 and 700 feet while the aircraft crossed the storm. Pilot Patrick Smith said the displacement was significant and suggested the horizontal stabilizers might have been torn off by exceptionally strong turbulence or an inappropriate response by the crew.

Images shared on social media prompted questions about whether the stabilizers were missing shortly before impact. On Monday, NTSB member Tom Chapman said there were indications the aircraft was breaking apart before it struck the ground. Investigators have not confirmed a structural failure or determined how much any individual factor contributed to the crash.

Sources: Olhar Digital.