Exhibit 12.4 West Texas Utilities Company Ratio of Earnings to Fixed Charges For Years Ended December 31, 1999 1998 1997 1996 1995 --------------------------------------------------- (thousands, except ratios) Operating income $54,164 $59,365 $44,567 $51,734 $59,486 Adjustments Income taxes 4,186 28,088 11,294 6,547 6,456 Provision for deferred income taxes 12,222 (6,578) (954) 5,718 1,971 Deferred investment tax credits (1,275) (1,321) (1,321) (1,321) (1,321) Charges for investments and plant development costs, net of tax -- -- -- (10,946) -- Other income and deductions 2,126 2,034 1,237 601 (463) Allowance for borrowed and equity funds used during construction 1,025 1,347 920 1,276 1,031 --------------------------------------------------- Earnings $72,448 $82,935 $55,743 $53,609 $67,160 =================================================== Fixed charges: Interest on long-term debt 20,352 $20,352 $20,352 $21,169 $21,413 Interest on short-term debt & other 4,731 4,580 4,911 4,925 4,111 --------------------------------------------------- Fixed Charges $25,083 $24,932 $25,263 $26,094 $25,524 =================================================== Ratio of earnings to fixed charges 2.89 3.33 2.21 2.05 2.63 4-19