An aircraft engine has two independent backup generators, $G_1$ and $G_2$. The probability that $G_1$ fails during a flight is $0.04$, and the probability that $G_2$ fails is $0.06$. However, if the main engine experiences a thermal spike (which occurs with a probability of $0.01$), the failure probability of both generators rises to $0.50$ each, though they still fail independently of each other given the spike. What is the overall probability that both generators fail during a flight?