For mechanics, the new contract includes 15 percent wage increases over six years. There also are improvements in health insurance and other benefits, compared with a previous proposal, but many TWU members have pointed out that they still are giving up ground there over their old deal. Stock clerks will get 10.5 percent wage increases. American is trying to shave $1.06 billion in labor costs to help the company restructure and leave bankruptcy. Now that contracts have been approved, layoffs could begin within 90 days.