EDUC8-or said:
Here's a question for you jumpers out there: How much room is "enough" when diverting around an airport with skydiving ops? When you exit the jump plane, where are you in reference to the airport? Does it depend on winds, etc...? I want to be cautious and I also want to teach my students to give you guys lots of room.
It depends on the winds aloft. We are subject to the winds just as much as an airplane is, so we are pushed by the winds aloft even in freefall. If the winds are an average of 60 knots between 15,000' and 3,000', we will be pushed 1nm downwind during freefall. We have to take that into account when spotting the load(determining the exit point). We then have to account for winds from our parachute opening altitude down to the ground. Most canopies don't fly very fast - 15 to 20mph at most - so if the winds are very strong, we can be flying into a 40 knot wind and backing up at over 20 knots.
Usually, exit points will begin just prior to the airport(unless winds are strong, then usually around the middle to end of the airport), and the jumprun will last until the last jumpers are out, or until they are at a point that the jumpers wouldn't be able to make it back to the airport. Usually, all jumpers are out within 3 miles of the airport, even in the worst winds. Jumpruns are USUALLY, but not ALWAYS, flown into the wind.
There is one more thing to worry about near DZ's. At some DZ's it's commonplace, at others they never see it. It's known as CRW - Canopy Relative Work, referred to by skydivers as "Crew". This is where a group of jumpers exit at normal altitude(10,000-15,000 usually, depending on aircraft used and DZ) and deploy their parachutes immediately, then fly formations while under canopy. These canopies descend at about 1,000fpm, so you can do the math and figure out how far upwind they will exit based on the winds aloft. 30 knot winds, we will generally get out about 6 to 8 miles upwind. We tend to err on the side of caution and exit further upwind than we need to....because if it turns out we exited too far up, we can always turn and run with the wind, and give us a 45-50 knot groundspeed in a 30 knot wind.