Old 747s had a window on the ceiling of the cockpit for using celestial navigation.[0] Also with the reliance on GPS and its inherent fragility has caused the

Old 747s had a window on the ceiling of the cockpit for using celestial navigation.[0] Also with the reliance on GPS and its inherent fragility has caused the US Navy to restart training in celestial navigation. In order to reboot the training regimen, the Navy is relying on Coast Guard instructors, since the USCG never stopped.[1] [0] http://www.airliners.net/aviation-forums/tech_ops/read.main/35528 http://www.airliners.net/aviation-forums/tech_ops/read.main/... [1] http://www.militarytimes.com/story/military/tech/2015/11/01/naval-academy-reinstates-celestial-navigation/74998554/ http://www.militarytimes.com/story/military/tech/2015/11/01/...