survreg 3-way interaction

I was wondering why survreg (in survival package) can not handle
three-way interactions. I have an AFT .....

You have given us no data to diagnose your problem. What do you mean
by "cannot handle" -- does the package print a message "no 3 way
interactions", gives wrong answers, your laptop catches on fire when you
run it, ....?
  Also, make sure you read help(frailty).  The following is a key line
"Use of gamma/ml or gaussian/reml with survreg does not lead to valid
results."

Terry Therneau