The loss of a Boeing 737 Max jet that plunged into the sea off Indonesia underscores the close of one of the safest periods for western-built airliners since the dawn of aviation.
Yesterday's crash of a Lion Air plane carrying 189 people was the fourth deadly incident since April involving a 737.
Before then neither Boeing nor Airbus SE had lost an aircraft since an EgyptAir A320 came down in the Mediterranean in May 2016, killing 66, a gap of close to two years.
Last year was the safest on record, with no passenger fatalities involving jets and only five customers dying in crashes of planes with 14 seats or more, according to consultancy Ascend FlightGlobal.
Early 2018 heralded a turn for the worse, when 170 people were killed over a 4 1/2-week period in three incidents involving turboprop models and a Russian-built Antonov An-148 jet.
April's death on a Southwest Airlines 737 in which a passenger was partially sucked out of the plane after an engine exploded marked the first fatal incident involving a Western jet since the Egyptair crash.
It was followed by the loss of 112 people when a 39-year-old 737 came down down while departing Havana in May.
There was also a single fatality as a 737 operated by Air Niugini landed in a lagoon in the Pacific island group of Micronesia on September 28.
Ascend FlightGlobal's Airline Safety & Losses review proclaimed after 2017 that "the age of zero accidents is here, more or less".
Following the tragedy in Indonesia, the organisation is modifying that prognosis.
"Last year was far better than the long-term safety trend would suggest and this year is certainly worse," said Paul Hayes, Ascend's safety director.
Because fatal crashes are now so rare, just one or two can have a major statistical impact, according to Hayes.
He says he now evaluates data against nine-year moving averages that show the industry is "a world away" even from the 1990s, when some years produced half a dozen crashes involving household-name carriers from Europe and the US.