crash, fall (down)
墜 centers on a heavy downward motion ending in impact or collapse: crashing, falling down, or dropping from a height.
墜 combines 隊 (which historically relates to a group or falling) with 土 (earth), suggesting something falling to the ground. The exact historical development of 隊 within 墜 is uncertain, but the overall phono-semantic structure is plausible.
The top 隊 looks like a formation of soldiers, and 土 is the ground. Picture a formation collapsing and crashing down to the earth.
For ツイ, imagine a heavy object falling with a sharp 'tsui' sound as it hits the ground: tsui -> ツイ, and the crash echoes.
fall; crash (of an aircraft)
shooting down (an aircraft)
abasement; fall; forfeiture; sinking (in people's estimation)
decline in public favor; fall in popularity
falling to one's death
plane crash
crash site (esp. aircraft)
death by falling
a great man dies; a great star falls