Hoping someone can help me out here. I am trying to book a flight for my uncle from Vietnam to visit in January to California for my upcoming wedding. He has a Vietnamese passport. However, his date of birth is listed as 1949. It does not list a month or day.

He also has a visa that states date of birth as XXXX1949.

I have never experienced this before and I cannot book a flight for him online because all the websites require you to enter a month and day. Can I call to book and will there be a problem at the airport going through customs? He has travelled here a few years ago and I am not sure how he booked a flight. Any help would greatly appreciated.