A Helicopter is a rotary-wing aircraft used by various governments, militaries and organizations. Helicopters usually land on marked helipads.
No One Lives Forever
There is a helipad at the top of the Dumas Towers. There were several Fuel Barrels present that Archer used to signal Tom Goodman that she had made it into the building.
As Archer is approaching the hidden H.A.R.M. base behind Dumas Lumber Company she is attacked by a H.A.R.M. helicopter patrolling the area.
UNITY Strike Force Epsilon used helicopters to assault Chateau Dumas. The team takes off before Archer can board. As they go back for her, the chateau explodes. Unbeknownst to them, Archer had escaped on a Gondola traveling down the mountain. H.A.R.M. sends several helicopters after her that she has to fight off.
No One Lives Forever 2
After a UNITY Intercept Team was able to infiltrate a Soviet Army base in Siberia and destroy the M-9 Data Processing Unit they headed to a nearby Cabin. When they radioed for pickup, Bruno Lawrie sent a UNITY helicopter to retrieve them. The team had to hold off a Soviet assault before the helicopter arrived.
When Lt. Joseph Anders destroyed a large portion of the H.A.R.M. Antarctica Base, H.A.R.M. sent several helicopters full of men to apprehend him. Archer and Magnus Armstrong had arrived at before them and encountered the rogue Super Solder. In attempt to get away, Archer used explosives to get past some barricades. This had the unexpected result of trapping Armstrong. Armstrong was able to delay Anders from perusing Archer as she had to leave to stop a war. Mischa reported that the H.A.R.M. helicopters were approaching. After she had left, Archer called Lawrie at UNITY Headquarters to request that he send a UNITY Intercept Team to rescue Armstrong. The team arrived just in time to see a H.A.R.M. helicopter take Armstrong and Anders away.
Helicopter on Wikipedia