Recently, the much-admired American Express CEO Kenneth Chenault announced that he is retiring after more than thirty years at the company. This announcement included the name of his successor, Stephen Squeri, 58, as chief executive officer as well as chairman of the board, effective on February 1, 2018.

Earlier, it was widely reported that American Express president, Ed Gilligan was the heir apparent. That plan was interrupted by the untimely and unexpected death of Gilligan at age 55 in May of 2015. The loss of a top leader is challenging in any case but more so when plans for a leadership transition are disrupted. American Express did not disclose the impact of Gilligan’s premature death on their plans but it seems likely that it required some rethinking.

The passing of a 55 year-old leader isn’t common but neither is it unheard of. The high-stakes scenario of CEO continuity and an ongoing responsibility of the board makes it imperative that plans are created with the understanding that future events may make the plan moot.

Leaders have to scour the landscape for opportunities and threats. #CEO Click To Tweet

For American Express, Gilligan’s death came not long after the announcement that a 16-year relationship with Costco would end. What did AMEX do? Adapt.

Such adaptation is greatly enhanced when leaders push themselves to identify and discuss low probability but high impact events, even if it is not possible to make plans for each. They know that acting as if they are in some safe zone leaves them vulnerable to the high-stakes issues that can emerge without warning such as the loss of a leader. The deal with Costco, though a major loss was not sudden but it was a blow nonetheless.

Time spent discussing “what ifs,” is not wasted for two reasons:

1. It pushes us to think more deeply.

2. These discussions are a form of rehearsal. Such rehearsal, even if only mental, helps us respond more constructively when a rare event does occur.

Directors and other leaders can too easily postpone discussions about highly unlikely events, dismissing the need to pay attention to them as “too theoretical” even if the issue is very high-stakes. Investors, customers, and employees expect leaders to think about what isn’t obvious.

Another shocking loss occurred when, in 2002, the president and CEO along with Senior Vice President of sales and marketing worldwide of AGCO were killed in a plane crash. The former CEO, Bob Ratliff, was immediately named to his former position. Though some had criticized Ratliff for staying too close to the business after he stepped down as CEO, it was lucky he did.

Ratliff served as Chairman and CEO until 2004, when Martin Richenhagen took the helm. Today, AGCO is thriving. They adapted.

American Express adjusted, adapted and so did AGCO. The specifics of each circumstance are beyond my knowledge and space here but the value of adaptability is affirmed in each of these stories.

If the lesson derived from these was “be adaptable” that would be incomplete. Flexibility, or the popular word “agility”, is a characteristic of healthy companies but it isn’t enough. Leaders have to scour the landscape for opportunities and threats; they need to look beyond and be adaptable. Both are necessary.