I've been meaning to post this for a few weeks. It was an odd situation that I still don't fully understand. But I found a solution that may be of help to others.

I originally booked XXX-CDG-SIN on all AF metal (with AF flight numbers) on DL.com (using Powertools on ITA). Called in and got a GUC applied on all segments to Business and reissued. That was back in early June for travel in September.

Then in late July, I got a voicemail from Delta stating that due to US ban on any DL flight number OR US airline ticket stock containing a flight that over flies Iran is not allowed. The agent stated that AMS-SIN via KLM is used for protection since KLM flights do not overfly Iran. He had rebooked me on KLM roundtrip. I immediately logged into my account and saw the reissued ticket on KLM metal via AMS-SIN.

I had paid about $800 more for the AF routing solely so I could avoid the inferior KLM J product (2-2-2 and poor food). So this new routing did not work for me.

Knowing that AF/KL support desk at Delta has access to both Deltamatic and Altea (AF/KL's system), I called the Diamond desk, explained the situation and asked if I could please be transferred to the AF/KL support desk directly. The agent agreed as they had no idea what I was even talking about. Once the AF/KL support agent answered, I explained the situation. The agent was a little baffled because they understood the embargo only impacted using codeshare DL flight numbers on the route. But she did see the notes from the previous agent that stating the 006 ticket stock wasn't allowed. She didn't agree and felt that it was okay to just restore the AF flight numbers, but agreed with me it might be risky if it gets flagged again (even if incorrect). I told the agent I really wanted the AF operated flights and would it be possible to restore them and reissue the ticket in Altea resulting in an 057 ticket number. I have had several past flights where AF schedule changes occurred and DL reissued new ticket on 057 so I knew it was possible, but didn't know if the GUC would present a problem. The agent was impressed with my understanding of ticketing and said she thought this was a perfectly acceptable and creative solution. In about 5 minutes she had restored all of the AF flights and reissued the ticket. Now on DL.com and AF.com I can see the 057 ticket number. Hopefully this is helpful for others in the future.

After I got the ticket fixed...I tried to find the details of said embargo on US flights online. I found this on FAA restrictions page: Federal Register :: Extension of the Prohibition Against Certain Flights in the Tehran Flight Information Region (FIR) (OIIX)

It does outline in section VI - F that codeshare flight numbers from US registered carriers are not allowed in restricted airspace. It makes no mention of ticket stock. Additionally...I looked up KLM's flights from AMS-SIN and guess what, they fly almost the exact same route over eastern Iran that Air France (and every other European carrier) do. So I'm not sure why DL thought the KLM flight was okay but not the AF flight.

Regardless, I got my issue fixed, but it was a very strange scenario that I am not entirely sure was a problem to begin with.