Two United Airlines planes clipped wings as they prepared for departure from San Francisco International Airport on Tuesday — the latest mishap involving air travel around the US. United Airlines Flight 863 was pushing back to begin its journey to Sydney, Australia at around 12:30 a.m. Tuesday when its right wing clipped the wing of Hong Kong-bound United Airlines Flight 877, the Federal Aviation Administration confirmed to CNN. The accident happened “in an area where air traffic controllers do not communicate with flight crews,” the FAA told the outlet.