"Don't worry - we're safe. The only noticeable effect this will have for us is that our total flying time will be ten hours instead of nine."
A few hours into the flight, the pilot informs the passengers that another engine had to be turned off due to mechanical failure:
"But don't worry - we're still safe. Only our flying time will go up to twelve hours."
Some time later, a third engine fails and has to be turned off. But the pilot reassures the passengers:
"Don't worry - even with one engine, we're still perfectly safe. It just means that it will take sixteen hours total for this plane to arrive in Frankfurt."
The mathematician remarks to his fellow passengers: "If the last engine breaks down, too, then we'll be in the air for twenty-four hours altogether!"
Did you know that: The Gimli Glider is the nickname of an Air Canada aircraft which was involved in an infamous aviation incident?
On 23 July 1983, a Boeing 767-200 jet, Air Canada Flight 143, ran completely out of fuel at 41,000 feet (12,500 m) altitude, about halfway through its flight from Montreal to Edmonton. The crew was able to glide the aircraft safely and subsequent investigation revealed fuel loading was miscalculated through misunderstanding of the recently adopted metric system which replaced the Imperial system. Not exactly a joke to laught at!!