I do not believe your assumption that the "Ground Zero" point is static can be true. Working under your assumptions, the Vigil II would never fire if you set your Altitude Correction for and LZ at least 900 feet below the take-off point. Let me explain myself more thoroughly. If your landing area is at sea-level (0 ft) and the take-off area is at 900 ft., then under your asssumptions, the Vigil will deactivate at an elevation of 1050 ft. because you have only adjusted the deployment altitude(which is now 1,040 ft. max), not the ground zero altitude (which is 900 ft.). Since the activation altitude (1,040 ft.) has been adjusted to below the elevation of ground-zero + 150 ft (1,050 ft.), the Vigil will never fire. The Vigil allows the LZ to be set as far as 6,000' below take-off point. I seriously doubt they sell a product that could be totally disabled that easily.
