SB 1089 expands funding eligibility for commercial service airports in certain areas. The bill amends the Transportation Code to allow commercial airports located in Texas-Mexico border counties with populations under 300,000 to qualify for financial assistance under the state's aviation facilities capital improvement program. It also includes airports that are jointly managed with a public agency from another state and serve a county adjacent to the Texas border. The bill allows these airports to receive funding, subject to federal funding restrictions.