Iberia’s board of directors has reportedly agreed the main details of a merger with British Airways but the size BA’s pension fund deficit could still be a stumbling block.The report quotes a source within Iberia. The two airlines will only say that their boards have held separate meetings to discuss a deal. The merger could only go ahead if BA’s unions agree to changes with regard to the more than three billion euro black hole in the pension plan. A deal would create the world’s third-largest airline by revenue. It would bring to an end negotiations which started 16 months ago. The merger is designed to help both airlines cope with the industry’s biggest downturn in decades.