It now seems that Mexico’s aviation safety rating was downgraded Friday due to concerns about the country’s safety oversight, according to the Federal Aviation Administration. This action will not stop flights between the United States and Mexico, but it will prevent Mexican airlines like Mexicana and AeroMexico from expanding their services to the United States.

Mexican airlines also will not be able to carry passengers to or from the United States in so-called code sharing agreements with other United States airlines. For those that do not know, code sharing means that one airline puts its code or symbol on another carrier’s flight and sells the seats as if the plane was their own.

Delta Air Lines, which is the current largest airline in the world, has a code sharing agreement with Aeromexico. People have also noted that American Airlines has a code sharing agreement with Mexicana. Thus, this new downgrade will affect all of these airlines. A spokesman for Delta Air Lines, Kent Landers, said that the airline will remove its code from AeroMexico flights. About 140 AeroMexico flights per day operate with Delta Air Lines’ code.

Landers went on to say in a statement that their customers are still permitted to travel on AeroMexico. However, they must be rebooked with an AeroMexico flight number to do so. The airline said it will work with the affected AeroMexico code share passengers so there is minimal impact to their travel plans. Of course, the airline did point out that earning or redeeming frequent flier miles will not be affected, because both airlines are still members of the same SkyTeam alliance.