While travelers have come to expect a near-instant reply, companies have been trying to meet that expectation.

Brian Kruse, a spokesman for Delta Air Lines, said it had increased its social media team by roughly 30 percent over the last year. Now, about 40 staff members monitor and respond to the roughly 3,000 tweets a day that Delta receives.

“If someone has a question about a delayed flight and they’re in the airport, that’s something we want to handle right then and there,” said Ashley Mainz, social business manager on the social business team at Southwest Airlines. It has a dedicated team of 29 that fields the roughly 80,000 posts a month that come through Facebook and Twitter, building from a base of just a few employees in a little over a year.

“Airlines were behind the curve, then they were able to figure out how to be proactive about it,” said Dana Miller, senior vice president for client services at Crimson Hexagon, a social media analytics company. She said data analytics revealed a continuous learning curve, because while the number of complaints had stabilized, the number of responses continued to climb.

From 2012 to 2014, the frequency of the word “apology” in response to traveler complaints increased by seven times, Ms. Miller said. Since then, the frequency of apologies has dropped, but the words “assistance,” “contact” and “help” have all skyrocketed. “The conversation or response is less regretful and more helpful.”

Jonathan Pierce, director of social media for American Airlines, said it had 26 people dedicated to social media customer service.

“You now see folks with Wi-Fi on board — if they need assistance on board, they’ll tweet us,” he said. “Perhaps if their bag isn’t there within five minutes, they’ll tweet us. “There’s an expectation from the customers that we’re there to listen to that and act on it.”