I don´t know if it requires a context, without it, I'd translate as fly loosely, maybe.
I´d add that if you use à toa with gastar dinheiro, gastar dinheiro à toa, you mean you´re wasting your money. Also, viver à toa, just wasting your life. However, you can say, estou rindo (laughing) à toa,meaning my life is just perfect, I have no problem whatsoever. Or something.
The adverbial expression "à toa" is a very common synonymous to the adverb "inutilmente" (literally, the opposite of "in some useful way"). However, literal "translations" are seldom suitable. If this is the whole sentence, it would translate as either of
To fly for no reason / To fly for no useful purpose / To fly in vain
In other words, we need the context in order to select one of these options, or something else, should "voar à toa" be a fragment of a longer sentence. I suspect we could give you a more precise answer if you could tell us more about your question (e.g., How did it come about? book? text message? something else? and What is the adjacent text, if any?)
-------------------------- AHA: X-post with Nonstar