The Grand Prix Drivers' Association (commonly referred to as the "GPDA") is the trade union of Formula One drivers. Its chairman is Alexander Wurz, with Jenson Button and Sebastian Vettel serving as directors. After the death of Roland Ratzenberger in qualifying for the 1994 San Marino Grand Prix, the reformation of the Association was proposed. Ayrton Senna was to be appointed as a director, but tragically died in the race itself. The reformation was completed during the weekend of the following race, the Monaco Grand Prix, with Michael Schumacher appointed as chairman.