New details about disturbing text messages written by a man aboard a San Jose-bound flight discussing how he planned to molest children were revealed when a federal complaint was unsealed.

Federal investigators said the text messages were exchanged between 56-year-old Michael Kellar and 50-year-old Gail Burnworth as Kellar flew from Seattle to San Jose for work on 31 July.

According to the Los Angeles Times, the pair discussed drugging and raping two children who lived with Burnworth, her ex-husband and her ex-husband's wife. One of the messages revealed the children are five and seven years old.

Kellar was caught texting Burnworth about the proposed sexual assault by a fellow passenger on the Southwest Airlines flight, who took a photo of his phone.

The passenger, a preschool teacher on holiday, alerted a flight crew member to the messages and the flight crew alerted police. Kellar was taken into custody when the flight landed.

Burnworth told Kellar she would have the two children to herself and she would drug them with Benadryl, the passenger's photo revealed. The complaint stated Burnworth told Kellar she would record herself molesting the children while they slept and she agreed to film him raping the victims as they slept.

The couple also discussed bestiality, other messages on their phones showed.

The two were charged Monday (August 7) with attempted enticement of a minor, including rape of a child and conspiracy to produce child pornography.

The passenger who caught Burnworth's messages was praised for her actions by San Jose police Sgt Brian Spears, who leads the Silicon Valley's Internet Crimes Against Children task force.

"One minute she is on her way to visit family on her vacation, the next thing you know her actions saved two children from continuous molestation," Spears said. "I feel she is absolutely a hero and was paramount to this investigation."

In an interview with The Mercury News, the teacher, who wished to remain anonymous said: "I'm being labeled as a hero. I don't need a bunch of attention. I'm just so thankful the kids are safe. I really just did what I did out of my heart. And being an early-childhood education, I'm trained to look for that."