FlyerTalk Evangelist and Ambassador: The British Airways Club
Join Date: Jun 2008
Location: Somewhere between 0 and 13,000 metres high
Programs: AF/KL Life Plat, BA GGL+GfL, ALL Diam, Hilton Diam, Marriott Gold, blablablah, etc
Posts: 33,116
It is effectively impossible to tell from booking data if a flight will be overbooked or not. As others mention, overselling is frequent but I have been on zeroed out flights with multiple free seats, and also on flights which showed 9+ in the cheapest buckets and where cabins were overbooked.