swinger you will find as you improve your skills as a recording crew pilot you do not have time to use a gps! Seismic is a memory game in which you must picture the grid in your head and "map" yourself in and "map" yourself out. Memorize the landscape to the finest detail, different colour tree, dead tree, tallest tree, rock outcroping, past the swamp, over the rock ledge, next to the creek etc. If these donot exist make your own, gently snap the top off a nice spruce on your last bag drop or couple of drops, or drill set up to give yourself an excellent "neon sign" to return to 5 minutes or 5 hours later...if you are going to the gps to mark the start of each rack, believe it or not you are costing your client money! you should be flying seismic not flying the aircraft or gps, if you know what i mean!Between alaska and california i only have about 6000 hours of seismic, so it would be benificial to get a second and third opinion! 😉 😉 😉 best o' luck, seismic can be a tough career to hoe! remember you are only as good as your last cycle...