• 墜落ついらく — a crash; fall from the sky
• 撃墜げきつい — to shoot down an aircraft
• 墜落事故ついらくじこ — accident involving a crash
• 墜死ついし — death from a fall
• 失墜しっつい — loss of trust, honor, or prestige

With the earth radical 土, 墜 shows something falling all the way down to the ground. It’s not a small stumble, but a heavy drop — a crash that leaves a real impact.