From Eli Saslow's article in ESPN The Magazine:
Their United Airlines charter flight to New Jersey lasted a little more than three hours. Midway through it, Fassel told his coaching staff to plan on going straight to work at Giants Stadium after the plane landed. He wanted to break down film and talk about what had gone wrong.
The Giants had a short week of practice before their next game, at home against the Packers. It felt like the only thing that mattered. The plane descended from the sky as the sun rose over New York City on Tuesday morning.
"You get used to seeing night turn into day as an NFL coach," Fassel says.....just after dawn, the Giants' charter plane landed at Newark International Airport and pulled up to Gate 14. Nearby, United Airlines Flight 93 idled on the tarmac. It was a cross-country flight from Newark to San Francisco scheduled to depart at 8 a.m.
Inside the airport, 37 passengers waited at the gate. Some drank coffee. Others read about the Giants' loss in the morning newspapers. Four men carried weapons, likely box cutters and knives, disguised as cigarette lighters.
At 7:39 a.m., the gate agent invited all of them to board.