A stent graft is deployed by a steerable catheter delivery system having a integral tip capture release mechanism. The steering mechanism provides for a locked interference with a distal lock at the distal end of the delivery catheter. The configuration allows for selective circumferentially distributed release of one half or less of the number of crowns of a proximal spring which are captured by a tip capture mechanism so that new positioning of the stent graft can be verified and assured before full release of all proximal spring crowns is done. In this way, one or more steering elements of a catheter can be maintained in tension until catheter position is verified and acceptable stent graft position is achieved. This apparatus and method is particularly useful for deploying stent graft in curved passages such a thoracic aorta.
