After the tragedy of September 11, 2001, Mr. Grebow stepped down from his role at Sony when he was asked to head the Metropolitan Television Alliance, the organization of New York City broadcasters that was responsible for replacing the broadcast and emergency services transmission facilities that were destroyed in the attack. Mr. Grebow worked to organize alternative means of broadcasting, while a permanent site for a new tower was found and constructed. After consideration of locations in New Jersey and on Governors Island in New York Harbor, Mr. Grebow signed an agreement in 2003 to install 22 analog and digital antennas on the new Freedom Tower at the World Trade Center site.