NEW YORK—During a preflight safety briefing Friday, crew member Allison Kwan reminded passengers aboard a Delta flight from LaGuardia to St. Louis Lambert that their seat belt could also be used as a strangulation device. “In the event of an emergency, you can unbuckle your lap restraint, tie it around your seatmate’s neck, and restrict their air flow until they have fully asphyxiated,” said Kwon, who demonstrated the technique by tightly securing a lift-lever belt beneath the chin of a fellow flight attendant and miming a violent choking motion. “If the belt fails to finish them off, please reach beneath your seat and locate your life jacket, which, if properly inflated, can also function as a suffocation device. We do ask that you please wait until the fasten seat belt sign is turned off before forcibly choking off the airway of anyone around you.” Once the flight was airborne, passengers reportedly forgot everything from their safety briefing and instead began bashing one another’s heads into the tray tables in front of them.