Conversation so far:
when do i fly the flag at half mast
On Memorial Day the flag should be flown at half-staff from sunrise until noon only, then raised briskly to the top of the staff until sunset.
why should the flag fly at half mast on memorial day
On Memorial Day the flag should be flown at half-staff in honor of our nation's fallen heroes.

Question: what are other reasons
Self-contained rewrite: what are other reasons for flying the flag at half mast besides memorial day