Having a captive customer base of hundreds of thousands of people may sound like every business's dream -- but not if "captive" means "held hostage" when your service becomes paralyzed.

This is effectively what happened to the airport management company, Aena, in December 2010. At the start of one of Spain's biggest holiday weekends, around 5,000 flights were cancelled and 700,000 people were left stranded when air traffic controllers went on strike, shutting Spanish airspace for 24 hours. Passengers, the media and the government alike all demanded answers -- but what was the message that Aena needed to communicate?

An ongoing dispute with air traffic controllers over their work conditions had finally bubbled over into a full-blown crisis. The government stepped in to declare a "state of alarm" -- an action not taken in Spain since its transition to democracy. Aena was facing one of the worst crises in its history.

The Buildup to Boiling Point
Like many crises, this one didn't arrive out of the blue, but had its makings in the fact that air traffic controllers were still operating under an expired labor agreement, which they were in the process of renegotiating with the government. They wanted new working conditions, permanent contracts and -- one of the big sticking points -- a base salary of 6,000 euros per month, the highest of any air traffic controller in Europe.

Tensions between air traffic controllers, Aena managers and the government were made worse in February 2010 when the government extended controllers' working hours without changing their existing conditions, which amounted to a salary reduction of 40 percent, and meant shorter breaks.

That summer, controllers took an unusually high number of sick days. Although some suspected this was a sly form of industrial action, the government went ahead and approved new work and rest times, which did not meet with the controllers' demands.

A warning shot was fired in November 2010 when controllers at the Santiago airport declared a wildcat strike on the grounds that they had already covered their set working hours for the year.

Other air traffic controllers threatened similar action at other airports, but Aena -- having lived with such threats for this long -- did not think they would go through with it.

On the morning of December 3, 2010, the government unveiled a package of new measures to tackle the economic crisis, including the possible part-privatization of Aena, which air traffic control staff considered a step too far. Ninety percent of controllers failed to turn up for their shifts, forcing the closure of Spanish airspace. No one could say when it would reopen, nor when flights would return to normality, given the number of canceled flights that now had to be rescheduled.

The pressure was on for the communications departments of all the various bodies involved to deal with this unprecedented situation.

Someone's Got Some Explaining to Do
The story made unflattering headlines internationally, as countries widely reported on their nationals being left stranded in Spain. Aena's competence was being questioned. Its communications department was flooded with inquiries.

Aena had the responsibility of communicating with customers, the public, the media and its own staff. For Aena's new communications director, this was the first major crisis she'd had to face, and the communications handbook didn't cover what to do for incidents on this scale. Working in her favor was her own professional background as a journalist. Prior to the crisis, she had built up good working relationships with the media.

For their part, the air traffic controllers issued statements through their trade union. The union spokesperson had the formidable task of trying to sway the media and public opinion, who were outraged not only by the havoc wreaked on their holidays, but also by wage demands that seemed completely out of order.

All parties had a lot of explaining to do. What messages should they send? How should they inform staff of the plan of action? How should they inform passengers? How should the true position of the air traffic controllers be explained? How could social media networks be used to get these messages across?

The clock was ticking. The military had been called in, holidaymakers wanted to travel, and defiant workers were being threatened with jail. Aena's new communications director had to decide, and fast. The world was watching.