People love to complain about airlines, even as airline service is improving dramatically.

In 2016, carriers invested billions in new facilities, new aircraft, improved employee compensation and better operations. And in May, a J.D. Power survey showed that customer satisfaction had reached a 10-year high.

"The airlines are clearly listening to their passengers and are taking action," the firm said. "As a result, we see satisfaction rising across all touch points of the passenger experience."

Airlines have long believed that the best way to keep passengers happy is to operate on-time flights. That cuts back on missed connections, lost bags and late arrivals -- the most common sources of unhappiness.

But in the end, no matter how much investment you make, it still falls on line employees to make airline travel come out right.

Not to say they're always successful, but many employees try every day. In this story, the top airline service moments of the year, which TheStreet publishes annually, we lay out a few examples. We contacted each of the major airlines for their nominations for this list.

Let's start with Felicia McMillan, a Newark, N.J.-based United (UAL) - Get Report flight attendant, who went out of her way to provide an abundance of care to an elderly man with dementia. He somehow ended up on her flight from Newark to John Wayne Airport in Santa Ana, Calif. The flight occurred Dec. 21, 2015, during last year's holiday travel season and too late to be included in our 2015 list.

In this case, United said in an employee publication, "an elderly man with dementia was sent to fly alone without any advance notice to us from his family about his needs. Within minutes after takeoff, the man began demanding to get off the plane, believing he was riding on a bus."

We cannot always assume that the flight crew will include people like McMillan. However, because of her, this trip turned out well. We know that because the passengers also included a registered nurse, who brought McMillan's conduct to the airline's attention in a letter to the airline.

"I have never been so moved to write a company about an unbelievable service I witnessed," the nurse wrote. "Felicia spent much of her time calmly and lovingly reorienting the passenger, walking him and attending to him with unparalleled compassion.

"I am a registered nurse and I have not seen many highly trained nurses accomplish what Felicia did with such grace," she wrote.

American Captain Eases a Passenger's Embarrassment

American Capt. Wade Suther

You never know what will happen in flight.

In May, on an American (AAL) - Get Report flight from Washington National to Miami, a passenger became incontinent.

Just before takeoff, the male passenger began to feel sick and briefly lost consciousness. When he came to, he said in a letter to the airline, he realized that "my loss of consciousness had been so profound that I found myself incontinent. So, not only did I have a medical issue to contend with, but I also had to figure out how to deal with one of the most embarrassing experiences in my life."

He went to the bathroom, tried to clean up his soiled pants, and returned to his seat. "The flight crew members were so very supportive, checking on me often and reassuring me that there was nothing to be embarrassed about," he wrote. "During the flight they kept watch over me and I suddenly had a small group of nurses, bringing blankets, food, drinks and caring."

This story could have ended, perfectly satisfactorily, with the landing at Miami.

But as the passengers disembarked, Capt. Wade Suther, a 28-year, Miami-based American pilot, approached. Suther wore "a warm smile and a concerned look," the passenger said, and asked, "What size pants do you wear?" The match was close enough that a few minutes later Suther returned from the cockpit with a pair of jeans.

The passenger changed in the bathroom, then thanked Suther. But Suther wasn't done. He retrieved the passenger's luggage and brought it to the gate. Then he asked, "Would you allow me to say a prayer for you?

"So right there, in the middle of the Miami International Airport, Captain Wade Suther clasped hands and prayed with his passengers and I wept," the passenger wrote. "{Suther} clearly took his responsibility as an airline captain to heart. To him, it's more than getting his passengers to their destination on time and safely. It's about truly caring for his passengers and not seeing us as numbers on a manifest."

To conclude this story, our passenger spent several hours in a hospital emergency room and planned an appointment with a cardiologist. Meanwhile, Suther received an American Airlines Chairman's Award, the highest honor the company has to reward employees.

Delta Helps During Thanksgiving Day Tragedy

Lane Kranz, Delta pilot

On Thanksgiving Day 2016, two Chicago parents learned that their son in the Wilmington, N.C., area had been involved in an accident. They needed to travel to see him.

The parents called Delta (DAL) - Get Report and got seats on the 6 a.m. flight out of Midway, with a change in Atlanta to Wilmington.

"The reservation agent must have made a notation on the reservation about the situation," according to a letter sent to Delta management by A320 pilot Lane Kranz. The gate agents upgraded the family, which included the two parents and their daughter, to first class.

"The family was crying, grieving and under tremendous distress and anxiety during the flight as they raced to see their son," Kranz wrote. "Upon learning of the situation, our flight attendants expressed tremendous compassion and grace."

After flight attendants informed the cockpit of the situation, the first officer contacted dispatch asking to arrange a connection by Delta's Porsche Transfer service. In Atlanta, Kranz informed the family that a Porsche would drive them to their connecting flight. Kranz noted "the look on their faces and the appreciation in their eyes -- the tears said it all."

By coincidence -- or fate -- the pilots were also assigned to the Wilmington flight. Agents and dispatchers pushed the flight out quickly. "Everyone involved did a fantastic job and the flight attendants on this flight were equally compassionate, caring, and supportive," Kranz said. "The family was in good hands."

Vacationing Alaska Employees Step Up to Prevent a Cancelation

Thunderstorms in July meant the pilots assigned to an Alaska (ALK) - Get Report Chicago to Seattle flight could not fly home because their eastbound flight had diverted to Milwaukee and they had timed out. As a result, the flight was about to cancel.

Fortunately, captains Garin Tentschert and Mark Allmann were in the airport, returning from a Wisconsin vacation with friends and family members including Marilee Tentschert, an Alaska flight attendant.

Another fortunate coincidence was that Daniel Craze, director of system operations, knew the two captains were in the airport waiting for standby seats. He also knew the flight was about to cancel. He suggested that Tentschert and Allmann might want to fly the plane home.

They were happy to.

Also the stars aligned. Both captains were checked out as first officers. "Most captains can only fly in the left seat," Allmann said. Both were carrying their pilot iPads, which are required for a pilot to fly. Irregular operations regulation let them fly without uniforms as long as they had permission from the chief pilot. John Hornibrook said OK.

One more: Marilee Tentschert was able to help the agents board the flight so that it could get going sooner.

"At this point, the flight had been delayed almost five hours and I would have done anything to help out, so we could all get home to Seattle," Marilee Tentschert said. "The passengers were so incredibly grateful and almost every one of them thanked me personally when they got on board."

Grateful for a culture in which everyone worked together to help out.

Hawaiian Honors a Pearl Harbor Survivor

On Dec. 8, following ceremonies honoring the 75th anniversary of the 1941 attack on Pearl Harbor, Hawaiian Airlines (HA) - Get Report carried Pearl Harbor survivor Ray Richmond home.

Richmond, 97 years old and now the second-oldest Pearl Harbor survivor, had been on the USS Oklahoma.

On his flight from Honolulu to San Diego, Richmond and the passengers got entertainment as flight attendant Lehua Beltrame-Tevaga performed a hula dance, accompanied by the musical group the Makaha Sons. Beltrame-Tevaga is the reigning 2016 Mrs. Hawaii.

The incident is shown on Hawaiian's Facebook page.

Southwest Mechanics Show Up to Fix a Broken Wheelchair

In August, a Southwest (LUV) - Get Report passenger disembarked from a flight at Baltimore-Washington International Airport and got her wheelchair back, only to find that it was missing a bolt.

Fortunately, two Southwest mechanics, Shaun Del Giudice and Ed Clifford, just happened to be walking through the airport.

The pair "immediately realized a bolt was missing," said an airline spokeswoman. "Without it, the chair was unable to stay upright and could not be pushed forward.

"Realizing the urgency of the situation, {Shaun and Ed} searched their toolboxes and found a matching bolt to repair the chair," she said. "Minutes later, the wheelchair was fixed and ready to go."

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