A TSB spokesman said the jet's flight date recorders had yet to be recovered.
The flight originated near Hartford, Conn., and the flight to Halifax was uneventful, Anderson said.
A pilot familiar with large planes said the tails of jets such as the 747 occasionally strike the ground during rotation - the point in the takeoff sequence when the pilot pulls back on the control stick, lifting the nose off the ground.
Large aircraft have so-called strike bars that protect the tail section when the pilot over-rotates and tail strikes the runway.
``It doesn't happen that often,'' said a pilot who didn't want his name used. ``You can encounter turbulence right at rotation.''
While tail strikes are uncommon, pilots can recover from them, he said.
In Ottawa, federal Transport Minister Jean Lapierre said ``my thoughts are with the families of the people involved in this tragic accident.''
Bill Fowler, a TSB spokesman, said the downed jet was likely equipped with depleted uranium, a radioactive material often used as ballast in the rudders and wings of wide-body aircraft.
Depleted uranium is the dense, heavy waste produced during the making of nuclear fuel and weapons.
A 747 may contain as much as 1,500 kilograms of the material, which is denser than lead and 60 per cent as radioactive as natural uranium.