"unplanned meetings" is a correct and usable phrase in written English.
You can use it to refer to meetings that occur unexpectedly or without advance planning. For example: "Due to the urgent nature of the issue, the board had to hold an unplanned meeting to discuss it."
Nursing managers reflected on the perceived burden of these unplanned meetings, despite careful planning on their part.
[Respondent 6, Gauteng Province] PHC clinic managers were frustrated by poor communication from regional and provincial health managers, who often requested information at short notice or summoned them to unplanned meetings.
The common reasons given for the irregular or absent supervisory visits were lack of transport, unplanned meetings at the regional level, inadequate personnel and lack of interest for surveillance activities.
Against this backdrop, Mr. Barak will fly to Washington for a previously unplanned meeting with President Clinton on Tuesday.
Without that unplanned meeting on the train, he said, he would probably never have attempted the mile record that day, on what might well have been his last chance to break the four-minute mark.
So it will be no great surprise if we are back here in Vienna for an extra, unplanned meeting before long.
Up in Canada a Vancouver Tweetup (an unplanned meeting announced on Twitter) helped clothe the homeless.
"Steve believed in the unplanned meeting, where you run into somebody in the halls, and Pixar was designed with that in mind," Lasseter said.
On Wednesday, AFL-CIO President Richard Trumka was called into an unplanned meeting at the White House to discuss late-stage negotiations on a proposed tax on high-end insurance plans.
Although Xi and Abe had a brief encounter during last year's APEC summit in Bali, the unplanned meeting was so awkward that Beijing did its best to downplay it.
In other words, the conservative leaders in the Council of Bishops likely conspired with other conservative organizations to get Davis a quick, unplanned meeting with the Pope in order to create the illusion that Francis was sympathetic to her plight and supported her refusal to grant civil rights to LGBTQ couples in her county.
