American Airlines and US Airways maintain that their merger would benefit consumers, in separate responses to the US Department of Justice's (DOJ) challenge to their proposed merger.
"This transaction will produce a stronger, more effective competitor more able to offer consumers the network and services they want," says Fort Worth, Texas-based American in its filing.
Tempe, Arizona-based US Airways calls the airlines' networks "incomplete" individually and says: "Without geographically strategic hubs and efficient and convenient connections from those hubs, American and US Airways cannot effectively appeal to travellers going to or from, or travelling within, these critical regions, and they necessarily lose business to the more complete networks that Delta and United offer."
Both carriers cite more than $500 million in consumer benefits in their responses, which were filed with the US District Court for the District of Columbia late on 10 September.
The Justice department claims that the merger is anticompetitive and will result in higher fares and stymie capacity growth, especially at a post-bankruptcy independent American, in its revised challenge that was filed on 6 September.
American and US Airways disagree with the DOJ's claim that the merger would enhance cooperation between the resulting carrier, Delta Air Lines and United Airlines by reducing the competitive heft of low-cost carriers like JetBlue Airways and Southwest Airlines.
These carriers as well as Spirit Airlines offer a significant amount of service in many of the overlapping connecting markets served by both airlines that the DOJ cited in its complaint, American says.
American also negated DOJ claims that the merger would stymie growth, saying that its pre-merger standalone bankruptcy plan to grow 20% by 2017 was always contemplated in a "manner that tracked industrywide increases in demand".
The carrier adds that its standalone plan was not supported by creditors and never presented to the bankruptcy court.