10 most difficult aviation riddles

English-made de Havilland DH 106 Comet was introduced in 1952 by British Airways. A year after, Comet airframes began suffering catastrophic metal fatigue, with three of them tearing apart during mid-flight.

Alberto Santos-Dumont was a Brazilian inventor and aviation pioneer. In his early career he designed, built, and flew hot air balloons and early dirigibles, culminating in his winning the Deutsch de la Meurthe prize on 19 October 1901 for a flight that rounded the Eiffel Tower.

They are: Airport London-Biggin Hill, Airport London-Heathrow, Airport London-City, Airport London-Gatwick, Airport London-Stansted, Airport London-Luton and Airport London-Southend.

Hans Baur (1897-1993) was Adolf Hitler's pilot during Hitler's political campaigns of the early 1930s. He later became Hitler's personal pilot and leader of the Reichsregierung squadron. Apprehended by the Soviet Union at the end of World War II in Europe, he was imprisoned in the USSR for ten years before being extradited to France on 10 October 1955, where he was imprisoned until 1957. He died in Herrsching, Bavaria, in 1993.

Roland Garros gained fame for making the flight from Fréjus in France to Bizerte in Tunisia. The following year, Garros joined the French army at the outbreak of World War I. Garros is sometimes erroneously called the world's first fighter ace. In fact, he shot down only four aircraft; the definition of "ace" is five or more victories.

On June 14–15, 1919, two British aviators flew a modified Vickers Vimy IV bomber (pictured) from Newfoundland to Ireland. Both men were knighted at Buckingham Palace by King George V. Eight years later, Charles Lindbergh's completed his flight from New York to Paris (the distance travelled by Lindbergh was almost twice as long).

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".

Amelia Mary Earhart was an American aviation pioneer and the first female aviator to fly solo across the Atlantic Ocean. In 1937 she tried to fly around the world, but after 40 days the contact with her aircraft was lost. Most likely she crashed somewhere over the Marshall Islands.

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).

Marine One is the call sign of any United States Marine Corps aircraft carrying the President of the United States. It usually denotes a helicopter operated by the HMX-1 "Nighthawks" squadron, either the large VH-3D Sea King or the newer, smaller VH-60N "WhiteHawk".