Handcuffs (not fluffy, as mentioned by a sibling). No key, just a latch. They are easy to release in case of emergency.
Source: was cabin crew and use of cuffs was part of the training.
Source: was cabin crew and use of cuffs was part of the training.
"We tried handcuffs but he got out." "You don't duct tape passengers, use the handcuffs." "I want to hear you acknowledge that the handcuffs didn't work!" "Duct tape is never the right solution..."
If injuries are a concern, there are also medical-grade restraints that are less dangerous than metal handcuffs.
Zip ties while used for temporary restraint by LEOs has weaknesses but medical restraints seem reasonable.