New Delhi, July 5 -- An American Airlines flight heading from San Juan, Puerto Rico, to Dallas was forced to turn back mid-air because of a passenger's big misunderstanding. Flight 1847 had just taken off when a woman saw the traveler next to her receive a text saying "R.I.P.", short for "Rest in Peace."

She panicked, thinking it was a threat to the plane, and told the crew. The pilot immediately declared an emergency, calling it a possible "level three" threat that could put lives at risk.

Following safety rules, the plane returned to San Juan's airport just 30 minutes after leaving. All 193 people on board landed safely while police rushed to investigate.

After landing, security experts from Puerto Rico's Office of Explosives and Pub...