What we know so far about the Metrojet mystery

Aired: 11/2/2015 | 0:04:55 | Clip
What downed a Russian airliner and killed 224 people on its path from Sharm el-Sheikh to St. Petersburg? The cause remains far from clear. Gwen Ifill speaks to Alan Diehl, a former National Transportation Safety Board investigator and author of "Air Safety Investigators: Using Science to Save Lives -- One Crash at a Time."