This article is about the new chief executive officer of United Airlines, Scott Kirby, who took over this month after four years as United's president.

But it's also about much bigger themes: longevity, succession, and even death.

The story starts last year, when United Airlines announced its CEO transition plan, which had United CEO Oscar Munoz making way for Kirby.

As I wrote then, United was a rarity because of the long transition period. Companies get new CEOs all the time -- 2019 was a banner year for it -- but Munoz and Kirby would continue working alongside each other for nearly six months before Kirby took over.

Even then, Munoz would stay on as United's chairman. So, I put a reminder in my calendar for the beginning of May: Check in with United Airlines, make sure nothing has changed.

Then, of course, everything changed. 

The clear takeaway

The coronavirus pandemic upended the world. Most of the United States went on lockdown. Airline travel was suddenly the last thing on most people's minds.

United Airlines has cut its schedule by 90 percent during May -- and even still, the airline endured uproars about overcrowding on some of the few United flights that remain.

But United stuck to the plan. On May 20, Kirby took over as United's CEO, and this week he spoke at his first public forum since the transition, talking for 50 minutes Thursday at the Bernstein 36th Annual Strategic Decisions Conference.

As I read the 8,600-word transcript of Kirby's talk, the lesson that every business leader should take away from United's transition became clear.

'The waiting was the smartest part'

I come neither to praise Kirby nor to bury him as a leader. He has a reputation for being blunt-spoken and numbers-oriented, and he's made some policy decisions that were not exactly well-received by employees.

(The "Bonus Lottery" announcement of 2018 comes to mind.)

He's also been in line for this a long time, previously holding the role of president at U.S. Airways and American Airlines before serving as United's president. 

But with apologies to the late singer Tom Petty: "The waiting was the smartest part." 

Smart business leaders face tough choices every day, but one brutal truth can be almost debilitating: Someday, if you're lucky, somebody else will be running your business.

With surprising frequency, however, transitions come up with no clear plan in place.

Very often, there's no plan--at least no publicly announced one. Take a look at what happened with the CEO transitions at rivals McDonald's and Subway last year. 

Can you tell me who would take over at Amazon if something were to happen to Jeff Bezos?

Even at Berkshire Hathaway, where Warren Buffett is now 89 years old, it was only in January that he announced a plan to give his two most likely successors as CEO "more exposure" to shareholders.

Leave a legacy

I have a theory about why United Airlines was the exception to the rule, and planned so far ahead.

First, Kirby has been groomed for this. Second, Munoz nearly died in 2016, and needed a heart transplant; he's only 61, but he had an early reminder that nothing lasts forever.

Finally, Kirby is an Air Force veteran, and I wonder if that might have played a role, since military organizations usually have a second-in-command who can step in if something happens to the commander.

Whatever the genesis, during one of the most challenging times for the airline industry in history, United was able to go ahead with this transition.

And that's the key lesson: If you're leading a business, think about succession. Face the fact that none of us will live forever. 

You might keep your plan close, and it might well change over time. But the mere fact of having it will give employees and other stakeholders confidence.

And, if the unthinkable yet inevitable happens suddenly, the organization you've devoted so much to will have the best possible chance at success.