In 1985 , Japan Airlines Flight 123 lost all hydraulic controls and its vertical stabiliser , and went into phugoid motion . While the crew were able to maintain near-level flight through the use of engine power , the plane lost height over a mountain range northwest of Tokyo before crashing into Mount Takamagahara . With 520 deaths , it remains the deadliest single-aircraft disaster in history
Japan Airlines Flight 123
Japan Airlines Flight 123
Phugoid