Airlines take people on some of the most important trips of their lives — to a wedding, a job interview or a trip back home from a war zone. And when things go wrong, passengers are increasingly turning to Twitter, Facebook or YouTube to rant about it.

Pressured as conversations heat up online, airlines are delving into social media as a new frontier for customer service. Atlanta-based Delta Air Lines led the charge into airline customer service via Twitter with its @DeltaAssist account a year ago and set up a social media lab. Think: Red Coat online.

While many businesses use Twitter for marketing, “Delta was the first one [among airlines] that fully embraced the potential of taking a ticked-off passenger and making them happy instantly,” said Steven Frischling, an airline social media consultant.

An example: Niels Hilbrink brought his father-in-law, who speaks only French, to the airport in Geneva for a flight to Amsterdam and then on to Seattle for his granddaughter’s wedding. He said he was told at the airport that his father-in-law would be on standby for the Amsterdam to Seattle flight because of overbooking, then tweeted: “@DeltaAssist impossible, you put my 74 year old father in law on standby for a long haul from AMS to SEA ... .” DeltaAssist responded in 10 minutes and the problem was sorted out within about 30 minutes, Hilbrink learning his father-in-law had a reserved seat. He then tweeted, “Thanks @DeltaAssist for the quick response and help!”

Delta ranked No. 1 for Twitter activity among airlines, followed by two foreign carriers: AirAsia and TAM in Brazil, in a ranking by airline brand consulting firm SimpliFlying in conjunction with website eezeer.com.

“They happen to be quite responsive and very quick to respond,” said Arnaud Bilquez, chief executive of eezeer, which rates airlines and hotel brands based on tweets.

One tweet even joked: “I hear you can even tweet @DeltaAssist if you’re in the rest room with no tp. I’m impressed.”

The airline could use some image building. Earlier this month, Delta slipped to No. 5 among traditional network carriers in customer satisfaction, according to J.D. Power and Associates.

Social media experts say responding to customers in real-time is particularly important for airlines because customers may have urgent problems or questions that, if addressed quickly, can help save a trip.

“For airlines, it’s extremely intense,” said Paula Berg, who helped pioneer the social media presence for Southwest Airlines before joining a public relations firm as a social media strategist. “Everyone’s traveling and everyone has something to say about it, good or bad. And it’s a real challenge for airlines to keep up with that.”

DeltaAssist agents monitor mentions of Delta on Twitter, and their responses sometimes surprise passengers who may have just been venting, but mentioned @Delta in their tweet.

Still, DeltaAssist doesn’t please everyone and customers aren’t afraid to show it.

Delta’s social media efforts only went so far when the airline faced an onslaught of harsh criticism after a soldier’s YouTube video went viral, outlining how Delta charged a group of soldiers $200 each for excess baggage when they were returning from Afghanistan. Amid a rush of tweets about Delta in the three days following, nearly 88 percent were negative, according to eezeer.

Berg said social media can’t prevent a crisis, but a crisis can escalate on social media. “Even the smallest issues can really spiral out of control,” Berg said.

Delta’s response time to the soldiers could have been faster, said SimpliFlying chief executive Shashank Nigam, but he thought the airline’s apology and commentary on its blog were personal and human.

Berg said she thinks Delta responded in a “progressive way” and made a relatively quick change in policy to bump up the number of checked bags allowed without charge for military.

“Of course, that doesn’t erase the problem that occurred or the public’s passion around the issue, but it shows the company is listening, acknowledging and adapting to customers’ expectations,” said Berg. “In fairness, that is the best they can do under the circumstances.”

Delta started the @DeltaAssist Twitter account in May 2010 after monitoring social media and realizing that customers were talking about Delta, “but we weren’t in the conversation,” said Delta spokeswoman Susan Elliott.

Since then, @DeltaAssist expanded to a 24-hours-a-day, seven-days-a-week operation run by 12 “social assist” agents to address problems in time zones around the world. While many companies have marketing handle their social media, the employees who handle the Twitter account for Delta are from reservations, bringing their customer service experience.

Delta is “doing a better job than they have [but] they still largely come off as this large, faceless corporation,” Frischling said.

Elliott said Delta’s aim on social media is to be “energetic, honest and respectful, and most importantly human.”

To be sure, there are risks with having myriad complaints about the airline out in the open for anyone to read, discuss and even retweet. “It keeps us honest,” Elliott said. “We apologize frequently throughout the day.”

Regardless of what the airline does, customers will still be voicing their opinions on social media.

“The upside,” Frischling said, “is it gives you your own forum to say, ‘I screwed up.’”