It is already evident that Eastern, the nation's seventh-largest airline, will not continue in anything like its present form.
The combined company would become the nation's seventh-largest airline.
The deal, which would create the nation's seventh-largest airline, must also be approved by Piedmont shareholders.
The nation's seventh-largest airline has had to roll back expansion plans.
It is the seventh-largest airline in the United States and carried 22.7 million people in 1991.
The department said it had decided that a full hearing on the bid, which would create the nation's seventh-largest airline, was necessary.
Eastern, the nation's seventh-largest airline, had 1,040 flights a day before the machinists' strike began last weekend.
Cathay is the world's seventh-largest airline in terms of the number of international passengers carried.
Southwest, the country's seventh-largest airline, said its revenue rose 13.2 percent in the last quarter from a year earlier, to $1.4 billion.
Texas Air bought Eastern, the nation's seventh-largest airline, in 1986.