The BBC enlisted the help of an explosives expert and a pilot with structural engineering and air accident experience, to determine the kind of damage the would-be Northwest 253 bomber would have caused.
On their site, you can see a video clip of the immense explosion, and the stresses caused to the outside of the plane. Thankfully, the experts concluded that the blast would not have destroyed the Boeing 747, and that the plane would have been able to land safely.
That isn’t to say that the explosion would have been a horrible thing to experience – the force of the blast would have killed the bomber and his seatmate, ruptured eardrums of many passengers, and blown body parts throughout the plane. The smoke, heat and noise would have made the whole thing quite traumatic.
Check out the BBC article for the video clip of this explosion, and an explanation of the kind of damage caused. The results of this test will be shared with governments and aviation experts around the world.
(As a commenter points out, the NW253 bomb was on an Airbus A330, not a Boeing 747)