I regularly jump from Sibson and from my experience it would be very unusual to exit outside the circle shown on the charts.
Normal exit from the Let is 13 - 13.5K. Freefall is down to between 5k (AFF students/tandems) and 2.5k for experienced jumpers. Normally we wouldn't jump with a wind groundspeed much above 20k. As we effectively drop through a tunnel over or close to our intended landing point a normal 60 second freefall would result in the following drift:
At 60nm wind speed 1 nautical mile
At 50nm wind speed .83 of a nautical mile
At 40nm wind speed .66 of a nautical mile
At 30nm wind speed .5 of a nautical mile
As the circle around a dropzone has a diameter of 5nm it is extremely unlikely that you would encounter a freefalling jumper outside the zone. On the other hand occasionaly the jump master will get the spot wrong so keep well clear. Its also worth noting that jumpers don't all exit the aircraft at the same time so there will be something of a spread although all would be expected pretty much to be within the dropzone shown on the ICAO charts.
TDL
Who exactly do you define as the management of the centre? I hope you do not include the Chief instructor in your critcisms. I agree with your comments about the staff but have found the
whole operation to be professional and Sibson has the best safety record of any drop zone in the UK.
Smarthawke,
I didn't notice the Robin on Saturday but watched two microlights in lose formation do an overhead join exactly over the landing pit.
Full opposite rudder
As not every pilot studies the notams before every flight isn't it better that every dropzone be considered constantly active. As a glider pilot for 27 years and a power pilot for 23 years I can't say that a 2.5 nm deviation from track is a major inconvenience to anyone.