A man who spent a night on the Bronte moors above Halifax after falling and breaking his arm was found by a Coastguard helicopter thanks to the GPS signal from a fitness tracking app.
Stephen Wright, 70, had set out from his home in Bradford on Monday afternoon to begin a walk on the moors above Haworth made famous by the Bronte sisters' novels.
He had planned a circular route that should have taken two hours to complete, but took a wrong turn. He then fell and broke his arm in the dark.
He managed to call his wife to tell her he was lost before his mobile phone ran out of battery and a huge search and rescue operation was launched.
He was located at 11am the next morning by Hull Coastguard's helicopter.
PC Sam Hollings posted on Twitter to describe how Stephen was 'exceptionally lucky' because a fitness tracker app installed on his phone was still emitting a GPS signal despite the device running out of battery. Other location-based apps were no longer functioning.
He advised people to ensure they had a geo-location app installed on their phone to help their relatives find them if they became lost.