Shares in Southwest Airlines (LUV -0.12%) declined by 18.1% this week through early Friday morning trading. The setback occurred after Southwest management gave a disappointing update at the JPMorgan Industrials Conference.Southwest disappoints the marketThe bad news is arguably as much about Boeing (BA 1.13%) as it is about Southwest. Unfortunately, the quality control issues at the former are causing airplane delivery delays. Southwest now expects to receive just 46 deliveries of the Boeing 737-8 airplane ...