Originally Posted by
BinSabai
agree with other posters: no detention, not even a second for passengers and crew, not for an overpaid smartphone and not even for 10'000 USD in cash.
however the OP has not yet ansered the question, whether he suspected some fellow passenger of the theft. In such asy worls alright! case, I could imagine that police would detain the suspected passenger for questioning. But it would depend on value and plausibility of accusation. Sure not for a phone cord and probably not even for a "lost" smartphone (professional thieves do not steal trackable smartphones and other such devices)...
Forget the legality of a detention and search, look at the logistics of it, 300 passengers and crew at around 5 minutes per person for a personal and hand luggage search, 25 police man/woman hours plus however long it would take to search the aircraft. Where would they conduct the search, on the air bridge? In the aircraft? For a phone!?!?! Fantasy world alright!