In 1974 Jack Jensen proposed a new way to stop hijackers from commandeering airplanes — each seat would be fitted with a solenoid-actuated lock in the seatbelt, an inflatable seat back, and a hypodermic syringe. Using remote switches, the crew could lock any passenger into his seat, force his head to his knees, and inject him through the seat cushion with “a strong sedative or poison.”

“Heretofore airlines have adopted numerous measures to curb hijacking, including observation of passengers, use of metal detecting devices, random searching of loading passengers, and the use of armed guards on the aircraft,” reads the patent abstract. “However, such measures … have been ineffective.”