AMR Corp. (BB-/Negative/--) unit American Airlines Inc. (BB-/Negative/--) said today that it anticipates recording a $990 million after-tax charge to write down assets in its third quarter that ended Sept. 30, 2002. Standard&Poor's Ratings Services said its ratings and outlooks for both entities are not affected. Most of the charge ($900 million) relates to writing off goodwill from its acquisition of Trans World Airlines Inc. assets in early 2001 and, to a lesser extent, goodwill from earlier acquisitions of smaller airlines. AMR had earlier said that it expected to take a write-off in this range under the new accounting standards for goodwill. The charges are almost entirely noncash and do not cause any covenant problems. More significant than