Editors' pick: Originally published May 27.

American Airlines (AAL) Chief Operating Officer Robert Isom is justifiably proud that following the 2005 merger of US Airways and America West, he presided over a widely acclaimed effort to make US Airways a high performance, on-time airline.

But in pursuing a similar effort at American Airlines, following a 2013 merger with US Airways, Isom has encountered resistance from the Allied Pilots Association, which represents American's 15,000 pilots and is concerned that the move poses a threat to the inviolate concept of captain's authority as well as to the airline's ability to make the best possible decisions regarding customer service --- decisions that it argues are best made on the scene, not miles away in the Fort Worth, Texas, control center.

In other words, if a passenger or group of passengers arrive at the gate one minute late, most likely after the door to the airplane has already closed, should the captain be empowered to make a decision to allow them to board?

The simmering issue surfaced last week following a meeting between APA leaders and top airline executives. At the meeting, "management reaffirmed its view that departure at "D-0" is a centralized, command decision, and pilots will not be granted decentralized latitude -- despite our role as the front-line operational leaders," according to an APA newsletter emailed to pilots shortly after the meeting concluded.

"D-0" or "D-zero" is airline speak for the moment when an airplane is scheduled to push off the gate. For airline operations, only safety is more important than schedule integrity, which cannot possibly occur without consistent on-time departures.

"There is an incredibly high correlation between departing late and arriving late," Isom said in an interview. "Take a look at the first flights of day. {After that}, aircraft rotate five or six times. If they pick up delays, those carry on throughout the day."

By holding a flight, even for a minute, "you may have handled one customer, but you may have delayed hundreds if not thousands of passengers," Isom said.

"We don't want to put that burden solely in our pilots' hands," he said. "There's no way anybody can know what has to happen with that aircraft throughout the day. It's a complex dance {involving} maintenance, customer service, the {operations} center, flight service, inflight, catering, customs -- a lot of different groups have to come together.

"What we try to do is to connect our pilots with ramp operations control then connect to {the operations center} so we have all the information coming together that no one person could keep straight, then give that feedback to the folks that need it," he said. "When things break down, if we leave a passenger off for some reason, we {typically} have someone who has already taken a look at that and taken care of that passenger."

As for captain's authority, "once the aircraft is loaded and ready to go, there has never been a question of captain's authority," Isom said. "That captain is in charge -- no ifs, ands or buts."

APA spokesman Dennis Tajer said strict adherence to a D-zero policy deprives captains of the ability to act in the interest of American passengers.

"Our gate agents who are in control of executing and closing the jet bridge door are under incredible pressure to close that door no matter what at D minus 10," or 10 minutes before departure, Tajer said. "When you see passengers having the door slammed in their face, passengers who are left behind with open seats on the aircraft, that rips at our airline's fiber."

"D-zero is an important feature of our job, but oftentimes it's a matter of a one-minute delay and we are going to arrive at our destination 10 to 15 minutes early," he said. The problem is that American "has centralized the timing decision in Dallas -- there's a myopic focus on 100% compliance with timing policy set in a centralized location."

Pilots who make a decision to delay typically face questioning from superiors and the threat of disciplinary action, he said. "If there is a one-minute delay off the gate, it is treated as if the airplane is 30 minutes late off the gate."

Tajer agrees with Isom that it's important for pilots to have all the information needed to make a good decision. For instance, an aircraft may have 40 people making connections, or another aircraft may be waiting to use the gate. Too often, such information is not shared, he said.

Delta (DAL - Get Report) appears to approach the sanctity of D-zero a bit differently than American does.

Last month, a captain at Endeavor Air, which flies as Delta Connection, was widely praised after he turned around an aircraft that had left the gate at Minneapolis-St. Paul International Airport, because he saw people gesturing frantically from an airport window. Airline staff had told the people it was too late to catch the flight, but Captain Adam Cohen said he responded to the look of desperation on their faces.

As a result, a woman and her three children made it to the funeral of Jay Short, her husband and their father, in Tennessee the next morning.

Delta spokeswoman Ashley Black said the captain's action conformed to Delta policy. "We want the Delta experience to be reflected throughout the travel experience," whether it be at Delta mainline or a Delta regional carrier, she said.

"We are committed to an on-time departure with every flight, {but} the difference here is that we empower our people to make the best decisions for our customers," Black said.

"Delta has a most expansive view of captain's authority," Black said. But generally, "at the end of the day, we require our captains to expand the team when they make the decision --  it doesn't serve anyone well for one person to make a decision for the customer."

Isom said that in reality, despite the optics, American's policy doesn't differ all that much from Delta's. Obviously, both airlines are firmly committed to D-zero departures. Moreover, Isom noted that American, like all airlines, invokes a much more liberal policy when it comes to the last departure of the day, because airlines uniformly seek not to strand a passenger at an airport overnight if they can avoid it.

"Those kinds of decisions are made every day," Isom said. "We want those decisions to be made with the benefit of all the information regarding all the passengers on board."

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.