By David Shepardson WASHINGTON (Reuters) -Major U.S. airlines oppose U.S. Transportation Department (USDOT) plans to update a government dashboard to show if carriers will voluntarily compensate passengers for lengthy delays within airlines control, a trade group told Reuters on Friday. This is the latest effort by the department to prod the airline industry into voluntarily committing to provide compensation and other benefits to passengers impacted by flight problems. Airlines and USDOT sparred over the summer about who was to blame for tens of thousands of flight delays and cancellations. A…