Boeing continues testing of the successor to the 747 with an abortive takeoff test.

The claim is the Boeing 747 is the safest plane in the world.  Boeing is working to continue that tradition with exhaustive testing with an eye towards certification of the 747-8.

On such test is the Abortive Takeoff Test.  This means loading up the 747-8 with full load of fuel, putting on bare breaks and running down the runway as if to takeoff.  Then right at takeoff speed the pilot slams the brakes.  Afterward measurements are taken to see how long it takes the plane to stop.  It has to stop within a defined distance to get the certification.