Talks between Boeing and its key manufacturing union broke down, and no negotiations are currently planned as the financially damaging strike heads into a fourth week.
The company withdrew its pay offer to around 33,000 U.S. factory workers on Tuesday, saying the union had not considered its proposals seriously after two days of talks.
The breakdown compounds financial and production problems at Boeing, one of the two primary global commercial planemakers.
The strike would cost Boeing over $1 billion a month, S&P Global Ratings estimated, while warning of a downgrade of its debt to junk territory. The company had a debt of about $60 billion.
(By Shivani Tanna and David Shepardson)