To obtain a green card for his fiancée from Brazil, your son can follow these steps, especially as he is in the Air Force, which can simplify some aspects of the process:

Steps to Obtain a Green Card for His Fiancée

1. 
   Engagement and Marriage

He and his fiance should ensure that they are legally engaged and plan to marry. They will need to have a marriage certificate after they tie the knot.

2. Choose the Right Path

He can either apply for a K-1 fiancé visa before they get married or directly apply for a spousal green card after marriage.

3. K-1 Visa Process (if they marry in August)

Your son needs to file Form I-129F, Petition for Alien Fiancé(e), with U.S. Citizenship and Immigration Services (USCIS).

After approval, the case is sent to the National Visa Center (NVC), then to the U.S. Embassy in Brazil for her visa interview.

Once she enters the U.S. on a K-1 visa, they must marry within 90 days.

4. Spousal Green Card Process (if married in August)

After marriage, he should file Form I-130, Petition for Alien Relative, which establishes the relationship.

Upon approval, they’ll submit Form I-485, Application to Register Permanent Residence or Adjust Status, if she is already in the U.S.

If she’s outside the U.S., she will go through consular processing at the U.S. Embassy in Brazil.

5. Complete Required Documents

Your son should prepare supporting documents, including proof of the relationship, financial support (Form I-864), and other required forms and documents.

6. Military Benefits

His service in the Air Force may expedite processing. He can inform USCIS of his military status, which might help if there are delays.

7. Stay Informed on Current Policies

Your son and his fiancée should stay up to date on any visa or immigration policy changes that could affect their case.

8. Consult an Immigration Attorney

It may be helpful to consult an immigration attorney specializing in military cases to navigate the process accurately and efficiently.