(Bloomberg) -- American Airlines Group Inc. Chief Executive Office Robert Isom on Saturday responded to a flood of concerns from pilots about the company’s underperformance, days after the union threatened to hold a vote of no confidence in management. The board of the Allied Pilots Association said in a letter late Friday that it wants Nick Silva, the union’s president, to formally present its concerns to American’s directors, arguing that the airline lacks a clear identity or credible long-term strategy.  ...