Is it a bad idea to go skydiving tandem when you have back problems?
It depends. Lots of people have back problems, spinal fusions,
etc and still skydive. The opening of the parachute can be quite
hard (not usually), and it can also cause a whiplash effect. Also,
a parachute landing could be on your butt, kind of like sliding in
on your rear end, which can also hurt your back.
So if your back has instability problems where this type of
force or motion could affect it, then better safe than sorry. Most
skydiving centers are able to help answer questions if you can
explain your specific back issue.