Letter D is perfect for what's being described thereby: D for "Disaster", "Dying", "Drowning" if the helicopter is flying next to the sea. It could be letter S, too, for "stall", "smashing onto the ground" or, if this acute pitch exerted onto the aircraft was deliberately maneuvered by the pilot themselves, a seven-letter word starting with the letter S.!science_memes@mander.xyz