More than 70 mountain rescue and police personnel have been combing the hills in the Lomond and the Trossachs National Park in a training exercise.
The teams took part in an emergency scenario involving several casualties.
Police said people would notice increased emergency services activity in certain areas around Crianlarich on Sunday, but urged them not be alarmed by this.
Those heading to the hills this winter were warned to "know their limits".
The exercise involved Police Scotland officers from Forth Valley Division along with volunteers from Killin, Lomond and Ochils Mountain Rescue Teams (MRTs).
The rescuers responded to a scenario involving a group of four missing walkers, while a second scenario with a further two casualties was added later in the day to add to the complexity of the incident.
The aim was to allow police and volunteers to plan and prepare for search and rescue incidents in the mountains of Forth Valley.
PC William Diamond, mountain rescue co-ordinator for the Forth Valley area, said: "Winter is one of the most dangerous times of year for those taking part in mountain activities.
"As the temperature and number of daylight hours decrease, the stakes for both police, volunteers and those being rescued become much higher.
"We make use of a range of specialist resources to assist in locating those who are lost and injured in the mountains, including helicopters and search dogs; however it is the local mountain rescue teams who undertake the vast majorities of searches and rescues."
He advised people heading into the hills this winter to plan their visit, dress for the weather and know their limits, and also urged people to leave some basic information including their intended route and return time with someone.
Ch Supt Thom McLoughlin, divisional commander for Forth Valley, added: "Mountain rescues can be difficult and risky for those involved.
"Therefore it is essential that both police personnel and volunteers have a strong understanding of the risks involved and the difficult and potentially treacherous conditions they could face."
Bill Rose of Killin MRT said: "The three teams train regularly in order to practice their skills, and by working together on an exercise such as this, it allows the sharing of ideas as well as practising how the teams can work together which is often required on larger searches or avalanches."