Boeing was generating optimism. Then on Thursday a 787 crashed, raising the specter of fresh problems for Boeing and altering the message it planned to send.

Net of cancellations and conversions, Boeing has logged orders for 512 planes this year, compared with 215 for Airbus. More orders could be signed next week at the Paris Air Show — a trade event where companies get a chance to showcase new technology and aircraft, and strike deals.

The Air India 787-8 crash could pose another long-term crisis for Boeing. Or not. But barring the crash, Boeing had been making seemingly significant progress in pulling itself from a multi-year slump.