A subcommittee of the US House of Representatives is holding a hearing to discuss the impact on employees of Delta Air LinesÔÇÖ proposed acquisition of Northwest Airlines. A number of employee representatives have expressed concern about the ability of the combined airline to meet pension obligations, so a hearing has been arranged in Washington today before the Health, Employment, Labor, and Pensions subcommittee.┬á┬á Associated Press reports that among the witnesses will be Robert Roach, general vice president of the International Association of Machinists; Patricia Fr