Stilton, I'm not an expert but I believe 67 degrees is the maximum sweep of the wings on a F3/GR1/4-a configuration that is used for high speed flight.
Normally, a landing would be performed with the wings fully swept forward (increased lift etc at 23? degrees) without any issues. However, should the variable geometry control in the aircraft go U/S then you may be 'stuck' at 67 degrees of sweep, and you have to get the aircraft on the ground.....
So I guess this was practiced in the sim and (possibly)in the air, like other in flight emergencies.