This article originally published at Helicopter crashes into kilometer-long slackline in Arizona, killing four.

Federal investigators are examining if a slackline was properly authorized following the deadly helicopter crash near ...

The people who strung the line - which is used in a sport akin to tightrope walking - had filed an aviation safety notice, ...

A half-mile-long slackline was hung across Telegraph Canyon, a recreational area located about 60 miles east of Phoenix in ...

Four people died in an Arizona helicopter crash Friday after the aircraft appeared to strike a more than half-mile long ...

Preliminary evidence indicated a slackline of more than 1 kilometer in length was strung recreationally across a canyon.