Janet DesRosiers was a regular flight attendant, then called a stewardess on the private Kennedy plane the Caroline.
One of her jobs was to give JFK a daily neck and shoulder massage as he relaxed in midair. Although she was the long-time mistress of Joe, Sr. she maintains that their relationship never romantically progressed beyond the backrubs, acknowleging however, that Jackie understandably was not too thrilled with the arrangement.
She was also charged with keeping Kennedy from using his voice as he flew, on orders of his speech coach, to save his voice for the next speech. They often communicated via writing after DesRosiers would give him a pad of paper.
On occasion he would write notes to her about his latest or wished for sexual conquests.
References
[4, p. 229-230]