Chapter 1169, Statutes of 1973 (58 911), modifies, for purposes of property taxation, the allocation formula used to assess aircraft owned by certificated air .carriers and scheduled air taxis. This act revises the aircraft assessment formula to exclude (1) all time prior to an aircraft's first revenue flight and (2) ground time in excess of 12 consecutive hours. The provisions of Chapter 1169 are effective for the 1974-75 through 1979-80 fiscal years, after which time the specified exclusions from the formula become inoperative. Chapter 1169 also requires the Legislative Analyst to report to the Legislature on the economic and revenue effects of this exemption. This report discusses (1) provisions of Chapter 1169, (2) background information on the aircraft maintenance industry, (3) state reimbursements under Chapter 1169, and (4) economic impacts of the exemption.