Some journalists on board were invited to join the presidential couple in the conference room.
All passengers kept a moment of silence.
The American president was on his way to Shanksville, Pennsylvania, where he was to deliver a speech commemorating the victims of Flight 93, which crashed in a field and all the people on board died, including jihadist air pirates.
Democrat Joe Biden, the rival of the New York billionaire, marked this moment in New York and is going to pay a visit to Shanksville on Friday afternoon (local time).
A bell marked the beginning of the commemoration of the September 11, 2001 terrorist attacks in New York at the World Trade Center Memorial.
A moment of silence was observed in the city, marking the moment when the first plane hijacked by jihadists hit the north tower.
Another five moments mark Friday’s ceremonies. They represent the moments when other planes hit the second Twin Tower, the Pentagon and the plane crash in Pennsylvania, but also the moments when the towers crashed.
Following a controversy over measures imposed against the spread of covid-19, two commemorations are taking place in New York.
At the official ceremony, at the Memorial, the organizers, worried that too many people are gathering, broadcast recordings with people reading the names of the approximately 3,000 victims of the attacks.
Simultaneously, at a ceremony held in the street, the relatives of the victims continue the tradition of reading their personal names.