NEW YORK — Flying on a commercial jet has never been safer. It will be four years on Tuesday since the most recent fatal crash in the United States, a span unmatched since propeller planes gave way to the jet age. Worldwide, last year was the safest since 1945, with 23 deadly accidents and 475 fatalities, according to the Aviation Safety Network. That was fewer than half the 1,147 deaths, in 42 crashes, in 2000.

Flying has become so reliable that a traveler could board a plane every day for 14,000 years without ever being in an accident, according to a calculation by the International Air Transport Association.