American Airlines and its unions continue to struggle with negotiations in what could lead to the largest US airline strike since 2005. The conflict stems from the airline’s close call with bankruptcy in 2003, when pilots, flight attendants, and ground workers all took pay cuts in order to help AA stay financially afloat. Now, these workers – represented by the Transport Workers Union – want the $1.6 billion in pay and benefits back, but AA isn’t meeting their requests.

The two parties have met with the National Mediation Board in order to negotiate terms, and since no satisfying resolutions have emerged, the union would now like to declare discussions at an impasse. The move is a common first step in obtaining permission to strike.

If the National Mediation Board agrees that no compromise will come from further talks, then it will issue a 30-day waiting period, which disallows a strike to occur, but creates a new opportunity for either side to come forward with another talking point.

Travel experts say that since AA is the world’s second-largest airline, a potential strike could possibly interrupt cash flow and disrupt flights during one of the country’s biggest travel seasons – summer. American Airlines has told the FAA that it will consider training managers and other employees as replacements in the event of a strike.

The last large strike the United States has seen was with Northwest Airlines in 2005, which ended by the airline hiring replacements.