Any member who becomes incapacitated for performance of duty because of disability determined by the retirement system manager to be of extended and uncertain duration, and who shall have completed at least ten (10) years of service, in the aggregate, credited under the retirement system, computed as provided in Section 2.124.340 of this chapter, shall be retired upon an allowance of one and one-half percent of his or her final compensation for each year of credited service, if such retirement allowance exceeds one-fourth of his or her final compensation; otherwise one and one-half percent of his or her final compensation multiplied by the number of years of service which would be credited to him or her were such service to continue until attainment by him or her at age sixty (60), but such retirement allowance shall not exceed one-fourth of such final compensation. (Prior code § 34.03.303)