I am extremely hard-pressed to think of ANYTHING more fundamentally STUPID…speaking as an honorably-discharged US military veteran of non-commissioned officer rank, who was an Army brat seventeen years before that. Let me fill you in on a verifiable FACT: "Sir" is derived from the word "sire," and what kind of complete IDIOT can imagine that a WOMAN is capable of SIRING…begetting offspring via the primal act of insemination?
Addressing a female officer as "Sir" is a gross insult. The ONLY reason congenital idiots think this a proper form of address is due to misogynistic bias, a completely unjustified belief that women are not capable of military command due to "genetic inferiority." This is the twentieth century. Women vote. They smoke cigarettes in public. They have careers. They are CEOs of multinational corporations. They are combat veterans. They are COMMANDERS.
Addressing a female officer as "Sir" should be a court-martialable offense, disrespect to a superior officer. You don't need male genitalia to command respect in a military unit. You need experience and authority. Whenever I've faced female [superior] officers, I've always addressed them as "Ma'am," which is a reduction of Madam, which is further preceded by "My Dame," a historically significant honorific of centuries-long standing.
The first time I addressed a superior officer as "Ma'am" was in 1978. Captain McCarthy* was the mother of one of my troop mates in Orlando. For a microsecond or two, I was unsure how to address her...but, it being eminently clear that she was not equipped with male genitalia, I called her "Ma'am."
The interaction was completely positive. I have never wavered since in my position, and have been disgusted by those misogynistically-prejudiced to speak contrarily.
*Captain McCarthy was in the United States Navy—a much higher rank than a US Army Captain…an O-6, versus a lowly O-2, a politically significant achievement.