Imagine settling into your economy class seat on a 13-hour flight, only to find a stranger’s shoes occupying the space beside you.

A new smart insole system that monitors how people walk in real time could help users improve posture and provide early warnings for conditions from plantar fasciitis to Parkinson's disease.

For shorter flights, etiquette experts advise keeping shoes on, while longer flights allow for shoe removal if feet are odor-free. Passengers seated in emergency exit rows should always keep shoes on ...