Marcus Moore reports on the travel chaos that unfolded after an electrical substation caught fire at London's Heathrow Airport and caused a significant power outage, forcing a complete shutdown of one of the world's busiest airports; Martha Raddatz has details on the two U.S. officials that confirmed a scheduled Pentagon meeting between Elon Musk and the Joint Chiefs was changed after a New York Times report said the meeting would include a top secret briefing on plans for a potential war with China; Melissa Adan has the latest on the urgent search for three women from the same family who went missing while driving after visiting the Grand Canyon; and more on tonight's broadcast of World News Tonight.