As a frequent airline passenger, I share Hobart Rowen's frustration with flight delays and cancellations {op-ed, July 23}. However, to use these airline service breakdowns as an argument against deregulated trucking markets is, in Rowen's words, "to ignore reality."

The Motor Carrier Act of 1980, which partially deregulated interstate truck transportation, has led to tremendous cost savings and more efficient distribution systems. Competitive rate structures and improved inventory velocity have contributed to a $56 billion annual reduction in logistics costs.

Because of new government emphasis on safety enforcement, competition has not harmed trucking safety, either. National data for truck-involved accidents, injuries and fatalities all show declines since 1980, both in raw numbers and per million vehicle miles.

The only problem with the 1980 act is that it did not go far enough. Vestigial entry rules, tariff-filing requirements and antitrust immunity for price fixing still exist at the federal level. And 43 states still regulate entry and rates for shipments that begin and end within their borders. Consequently, intrastate rates in some states are twice as high as comparable interstate rates, on which discounting is allowed under the 1980 act. Transportation options available to private truck fleets on interstate movements are often prohibited if the service does not cross a state line. Total economic deregulation would add another $228 billion in annual cost savings to businesses and consumers by 1990.

Finally, the regulated trucking industry has not been destroyed by "cutthroat competition." In 1986 the industry had a collective 13.5 percent return on equity, substantially higher than that of virtually all the shippers that use trucking services.

Regardless of one's thoughts on airline deregulation, trucking is a separate industry with discrete price and service characteristics. The American economy has improved its distribution capabilities with partial trucking deregulation. RICHARD D. HENDERSON Executive Vice President Private Truck Council of America Washington