My sister is here on a visa but has we have also applied for a green card she has an interview on the 11th?

Question

and has a flight back home on the 12th, my question is can she fly back home on the 12th or does she have to wait for her green card to get here before she can fly back to istanbul to see her children or can she still fly with her visa?

Answer 1

My advice is that she should not leave the US until she has her green card.  Further you don't know what will happen on the 11th, so you are really cutting things short.  Assuming that there's no higher penalty to cancel or change itenerary on the 11th of Aug than today, then I would expect that her passport (I guess from Turkey) will be stamped noting that she is approved for a green card pending.  Meaning she can travel back and forth with her passport to Turkey.  This however, is assuming she is approved, and no further papers are pending.  

No her status is not cancelled unless she leaves the US without the stamp from the INS office on 11th of Aug.  U can ask the agent this same question on the 11th to verify.

Answer 2

If she leaves the U.S. while her green card application is still being processed she is considered to have abandoned her application. All of her paperwork would need to be redone. She can either wait here or apply for an I-131 (Advanced Parole) so that she may travel without 'abandoning' papers.

Answer 3

Once she is approved Green card at the interview, Immigration Officer will take away I-94 and will void her visa by updating her PR status in the system. Therefore, she will be questioned about her status at the airport. It is better if she leaves after she gets the actual green card in her hands.

If she has to leave US for the emergency reason, then she has to make an appointment through InfoPass, to get temporary I-551 stamped on her passport.