Practice is key to assuring that a catastrophe plan will work as effectively as possible.

That was the case with Aon P.L.C. when Superstorm Sandy forced its New York office in Lower Manhattan to close last fall October for a few months, said Stacy Summers, Aon's Chicago-based vice president-global business practice.

“Having a plan is great; practicing that is essential,” said Ms. Summers, who leads a group of 18 professionals across six countries. “Our first and foremost priority is the safety of our colleagues.”

Aon operates a global emergency operations center in Chicago. Ms. Summers said that as part of its preparation for catastrophe, the emergency operations center can call upon the expertise of meteorologists on staff through Aon's Aon Benfield unit.

“A big part is making sure we're putting the right provisions in place to keep our colleagues safe,” she said.

Ms. Summers said “a big piece of preparation is training.” This includes having a communications plan in place for colleagues, clients, vendors and markets. It involves focusing on business priorities, including recovery “focusing on continuing service to our clients,” she said.

Aon's preparations started well in advance of Sandy, focusing on 65 offices across 16 states and Canadian provinces. The brokerage activated plans the weekend before Superstorm Sandy struck. This included having an emergency notification system, which proved very valuable, Ms. Summers said.

Aon activated contingency plans at 26 offices in New England, the Mid-Atlantic and Canada, which affected more than 4,000 employees including traveling personnel in the areas. But within five days of Sandy hitting, only two offices remained operating under contingency — in Manhattan and Somerset, N.J.

%%BREAK%%

Ms. Summers said that once Aon learned of the storm's effect in New York, which affected more than 900 employees, the company set into motion plans that allowed employees to work virtually or transfer work to other colleagues. Aon outfitted more than 500 temporary workplaces with desks and Internet access across 11 offices in four states stretching from Pennsylvania to Connecticut.

Employees could use one of those spaces for a day, a few hours, or weeks, she said.

Ms. Summers said that when the company learned that it would have to contend with longer-term power outages, its real estate team worked with multiple property managers in New York to procure office space. Aon reopened an office in Times Square by Nov. 12 to provide meeting space, which enhanced the ability to cooperate and collaborate. Aon also acquired some property on Park Avenue, from which operations began on Nov. 19.

Aon pulled in experts from around the world to facilitate the recovery, furnish offices, set up networks, and even provide welcome packages for workers in temporary spaces, she said.

Ms. Summers said she is “absolutely” satisfied with the way the plan responded before, during and after Sandy.

“We put a lot of thought into practicing and implementing plans,” she said. That enabled colleagues “to do their jobs, which is supporting all of our clients.”

%%BREAK%%

Ms. Summers said Sandy showed that “colleagues need to have time to take care of families and personal situations,” so enabling special support services for them was very beneficial. This included such actions as activating a special expenses reimbursement process, she said.

“You can underestimate the need to help your colleagues,” she said.

For a catastrophe plan to work, the planner has to make sure “that you're taking the time to train your business leaders,” she said. That includes telling them what to expect and how to respond because “they will have to make rapid decisions without as much information” as they might have under normal circumstances.

Executive engagement also is critical, Ms. Summers said. Aon CEO Greg Case was “extremely engaged and supportive of our recovery efforts,” she said. He sent regular communications to colleagues and attended multiple meetings with colleagues.

The New York office was up and running right after the New Year, she said. “We were always open for business; we never truly closed,” she said of the contingency operations. “We didn't skip a beat” in providing support to clients.