just what happened to this a321. despite the damage, the plane was repaired. if it s done properly and done by a mechanic that s experienced and the procedure is followed, it shouldn t be an issue. reporter: airbus vigorously tests its planes for such a possibility. we go beyond the limit by putting the tail on the ground and slowly accelerate. reporter: for the tests, the planes are equipped with a special skid to prevent damage, shown in this airbus flight material. if it s too harsh, we can stress the repairs. reporter: but tail strikes can be deadly even years after the incident. august 1985 in japan, the deadliest single crash ever. a packed 747 slams into the side of a mountain leaving 520 people dead. it was a similar type of circumstance. they had a tail strike. the repair was made and then