UMs are children under a certain age who travel alone on the flight without their relatives/parents. Their well being and safety are in the hands of the operating cabin crew.
On a certain flight arriving into S'pore, an UM (small girl of about 6 years) left the aircraft with a male passenger who was a total stranger to her. The male passenger had befriended the UM during the flight and had told the chief steward he was a relative of hers. Mind you, no one else was supposed to bring the UM to the waiting relative/relatives at the arrival hall except a dedicated ground staff.
On arrival at S'pore, the UM's grandfather was waiting at the arrival for the ground staff to hand over the little girl to him. He waited for more than 2 hours before alerting the ground staff that his grand daughter was missing.
There was frantic search for the UM and it was discovered that she was with the male passenger "touring"the arrival area of the airport.
A formal police report was lodged by the grandfather. He also filed a lawsuit against the airline.
A medical check was carried on the UM and fortunately there was no sign of injury or molest.
The case was settled out of court. The chief steward who was the crew-in-charge was almost sacked.