How to tell kid we can't go to asia because dad is too unhealthy for long flight?

Truth: This is easy, you tell them the truth; dad can't make such a long trip because he will get sick. Explain it's only dad's problem, and a brief explanation why, then answer questions honestly and simply. This doesn't mean your child can't dream of asia though. My kids want to go to south america, and I have no intention of going soon either.