Two Boeing 747s collide causing the deadliest accident in aviation history. KLM Flight 4805 and Pan Am Flight 1736 prepare for takeoff at Los Rodeos Airport on Tenerife. One plane starts to takeoff without clearance, heading towards the other. What happened to cause these two planes to collide on the ground? Find out on this episode of Black Box Down. Follow us on Twitter and Instagram @BlackBoxDownPod. https://twitter.com/blackboxdownpod https://www.instagram.com/blackboxdownpod/ Sponsored by ExpressVPN. Head to http://expressvpn.com/blackboxdown today and get an extra 3 months free on a 1 year package! Also sponsored by The Jordan Harbinger Show. Go to http://jordanharbinger.com/subscribe to check out the Jordan Harbinger Show today! Learn more about your ad choices. Visit megaphone.fm/adchoices