New York (CNN) -- "Unauthorized and unprofessional" is how an internal memo describes the conduct of an air traffic controller, who allegedly allowed his two young children to speak with pilots on an air traffic control frequency, and his supervisor, who allegedly allowed it to happen.
The memo, dated February 25, was written after the facilities manager for the air traffic control tower at New York's John F. Kennedy Airport learned about the incident, a source who has seen the memo told CNN.
"The display of professionalism in the past by the control personnel at this facility has been exemplary," the memo said. "However, a lapse in judgment for what may seem a minor transgression diminishes our credibility and slights the high standards of professionalism."
It was not immediately clear what prompted the manager to write the memo or how he found out about the incident, the source said.
The incidents occurred on succeeding days last month at JFK, the Federal Aviation Administration said this week, and the controller and the supervisor have been placed on paid administrative leave.
"We have an incredible team of professionals who safely control our nation's skies every single day. This kind of behavior does not reflect the true caliber of our workforce," FAA Administrator Randy Babbitt said in the statement Wednesday.
Babbitt was referring to the February 16 incident involving the controller's young son, who is heard in a recording -- posted on liveatc.net -- clearing a JetBlue flight for takeoff and later speaking to an apparent Aeromexico flight.
Later, an FAA official, who asked not to be identified because of the ongoing investigation, said the controller brought his daughter into the same tower the following day, and the child was allowed to talk with pilots of two planes.
A separate source said the supervisor "should be making sure that things like this don't happen."
Yet another source familiar with the investigation said the two children are twins.
The controller who brought the children to work later reported that he had done so, the source said. The controller and supervisor involved are veteran employees, the official said.
Dave Pascoe owner of the Web site where the recording of the air traffic communications is posted, told CNN he thinks the attention the incident has drawn is "ridiculous" and it has been "blown out of proportion."
In the recording, a child says, "JetBlue 171, cleared for takeoff."
A man then tells the plane, "Here's what you get, guys, when the kids are out of school."
The pilot chuckles and says, "Wish I could bring my kid to work." The same pilot later tells the child, "Awesome job."
During the recording, which is dated February 17, the child also speaks to an apparent Aeromexico flight. A recording from the following day, when the daughter was reportedly in the tower, also was posted on the Web site.
FAA spokeswoman Laura Brown later said the incident took place about 7:30 p.m. February 16.
Pascoe said most people "in the aviation community felt like this was (not) anything more than a noble thing, that a father would take his kid to work."
"It was one incident where a kid was up in the control tower," he said. "If you know anything about aviation, you know that the air traffic control towers are highly supervised. ... A father was taking a child to work and let the kid clear planes for takeoff and now the world thinks it's an unsafe place."
The FAA has suspended all unofficial visits to air traffic control operational areas during its investigation into the incident. Babbitt has directed a team to review air traffic control policies and procedures related to facility visitors.
The National Air Traffic Controllers Association, the union representing controllers, issued a statement, saying its members "do not condone this type of behavior in any way."
CNN's Susan Candiotti contributed to this report.