The most difficult airlines riddles

Delta Air Lines, Inc. (NYSE: DAL), commonly referred to as Delta, is a major American airline, with its head­quar­ters and largest hub at Harts­field­–­Jack­son Atlanta In­ter­na­tion­al Airport in Atlanta, Georgia. In 2013, Delta Air Lines was the world's largest airline in terms of sched­uled pas­sen­gers carried (120.6 mil­lion).

KLM was founded in 1919. Op­er­a­tions stopped during World War II apart from the op­er­a­tions in the Dutch An­tilles. The airline is the "Oldest op­er­at­ing air­line", but with the 2004 merge with Air France some dispute whether KLM should still hold the crown. QANTAS, founded in 1920, is dubbed "Oldest con­tin­u­ous­ly op­er­at­ing air­line".

About 17 hours. The flight between Qatar-New Zealand takes 16 hours and 20 minutes. It is cur­rent­ly the longest pas­sen­ger flight in the world, operated by Qatar Airways.

Korean air­lines. The Korean Air logo fea­tur­ing stylized "taegeukgi" design was in­tro­duced on 1 March 1984. The same symbol is used in the Korean Flag.

Approx 35,000 ft. Air­planes fly at high al­ti­tudes because of the re­duc­tion in drag, and to get into the jet streams. The Polar Jet stream ranges from 23,000 ft to 40,000 ft. The sub tropical jet stream range from 33,0000 ft to 50,000 ft.