The airline said Friday that Oscar Munoz had been admitted to a hospital without providing further details. “We need to know who is speaking on the behalf of the company and who is accountable for the decisions of this great airline,” said Jeffrey Sonnenfeld, a corporate governance expert and a professor at the Yale School of Management. While United might be waiting to provide comment out of respect for Munoz’ privacy, the company also has an obligation to shareholders, Sonnenfeld said.