There are at least two questionable aspects to any will, including your quickie. First, is it yours? The 'holograph' will—entirely in your own handwriting and signed—has been held to answer that*, but getting witnesses as well can't hurt.
But the second issue's harder: whether your wishes are clearly expressed, lawful, and address the possible rights and claims of those you leave behind (who might later contest it) For this you would want a lawyer's advice, or at least the advice of a will kit.
But if the plane's leaving in an hour, write out your wishes and hope for the best. Get the real thing as soon as you get back.
Because you will, you know, bon voyage.
*The storied case was a farmer who died when his tractor rolled over, but was able to write "All to wife" and sign his name in the dust on the fender before succumbing.