The tool can pick up social media posts from platforms like Instagram, Foursquare and Facebook from any lounge guests who have enabled geolocation services on their mobile devices and “checked in” to the lounge, or in the case of Facebook, activated the “places” function -- whether they are using the airport’s Wi-Fi network or their own service provider. While it also scans for specific mentions of the Qantas brand on platforms like Twitter, it can also capture many posts where the airline isn’t mentioned at all.

Qantas’s lounge staff members have been equipped with iPads that receive an alert whenever a user posts content from that location. The airline uses the system in all its premium lounges in Australia, as well as in several others around the world, including Singapore, Los Angeles, Kennedy Airport in New York, London Heathrow and Dubai.

Rohan Kissun, 30, who flies twice a week with Qantas, said he often used his downtime in the airline’s lounge to browse and update his social media accounts on his mobile devices. Although he is tech savvy — he works for an Internet security firm — he was unaware of Qantas’s monitoring system until a reporter told him about it. So he had no clue of what was about to happen one morning last month when he was in the Qantas business lounge at Sydney Airport.

Noticing Australia’s former prime minister, John Howard, at the buffet, Mr. Kissun asked to take a picture with him on his smartphone, which Mr. Kissun then posted to his Instagram account with the comment: “Not normally a selfie taker … but couldn’t resist with our former PM this morning.”

Shortly thereafter, Mr. Kissun noticed that someone at Qantas had seen and “liked” the image, sharing it with the airline’s more than 26,000 Instagram followers.

“I was quite taken aback,” Mr. Kissun said. “I would not have thought that photo could have attracted any attention from them.”

Image A Virgin Atlantic employee used Google Glass to check in its premium-class passengers arriving at Heathrow Airport. Credit... Simon Czapp/Solent/Virgin Atlantic

Mr. Kissun said that he would prefer Qantas to be more transparent with customers. Now that he is aware of the practice, he said, “I would be more inclined to calm down about what I’m uploading.”