On Friday, President Trump signed into effect an executive order titled "Protecting the Nation from Terrorist Entry into the United States." The order puts a variety of restrictions on the entry into the U.S. of aliens (non U.S. citizens) from Iran, Iraq, Syria, Libya, Somalia, Sudan and Yemen.
Section 3(c) of the executive order states that immigrant and nonimmigrant aliens from these countries would be detrimental to the U.S. and suspends entry into the U.S. of such persons for 90 days on a blanket basis. This would include green card holders and there is no express exclusion for airline crew. IATA has been informed by the U.S. government that crew are subject to this ban.
We recommend that green card holders from the above countries not accept assignments outside the U.S. until the government has confirmed that they will be permitted to return to the U.S. without challenge. As of this moment, statements from the U.S. government have not provided assurance on this point.