That is a possibility, given the hostility recently expressed by the Department of Transportation to airline acquisitions that involve heavy borrowing and to acquisitions in which a foreign airline is a partner.

The protocol was a key element of the settlement because the union was concerned that the Reno deal would set a negative precedent for much larger airline acquisitions by American in the future.

The deal would be the largest airline acquisition ever, said Raymond E. Neidl, an industry analyst with Dillon, Read & Company.

The Secretary's Veto Power Mr. Ford's bill, and a companion measure being drafted in the House, would require the Transportation Secretary to approve any airline acquisition in which more than 25 percent of the voting power changes hands.

A bill to forestall airline acquisitions moved ahead on Capitol Hill today, over the objections of the Bush Administration.

Facing the prospect of further airline acquisitions financed by heavy debt, regulators and lawmakers are examining whether to act against deals like the $121-a-share agreement for NWA Inc. that was announced on Monday.

Review Could Set Precedent Although Mr. Skinner is said by his staff to be approaching his department's review of the Northwest takeover with an open mind, the review is expected to be especially thorough and could set a precedent for future airline acquisitions.

The British, in essence, are holding the Heathrow rights hostage until they get their ultimate goal: an agreement that would greatly open each country's domestic market to the other's airlines and make cross-border airline acquisitions possible.