Air time is the feeling of weightlessness

Weightlessness

Weightlessness is the condition that exists for an object or person when they experience little or no acceleration except the acceleration that defines their inertial trajectory, or the trajectory of pure free-fall...

 or negative gravity force experienced on a roller coaster

Roller coaster

The roller coaster is a popular amusement ride developed for amusement parks and modern theme parks. LaMarcus Adna Thompson patented the first coasters on January 20, 1885...

 or other amusement ride

Amusement ride

Amusement rides are large mechanical devices that move people to create enjoyment. They are frequently found at amusement parks, traveling carnivals, and funfairs.-Notable types:*Afterburner*Ali Baba*Balloon Race*Booster...

s. On roller coasters this feeling is usually achieved by the train going over a hill. Hypercoaster

Hypercoaster

A hypercoaster can mean one of two things:*Any continuous-circuit roller coaster with a height or drop measuring greater than 200 feetOr, more narrowly:*A style or model of roller coaster with three features:**A height of 200–299 feet...

s such as Magnum XL-200

Magnum XL-200

Magnum XL-200 is an Arrow Dynamics steel hypercoaster located at Cedar Point in Sandusky, Ohio. Built in 1989, it was the first complete circuit roller coaster to break the barrier...

 at Cedar Point

Cedar Point

Cedar Point is a 364 acre amusement park located in Sandusky, Ohio, United States on a narrow peninsula jutting into Lake Erie. Cedar Point is the only amusement park with four roller coasters that are taller than...

 and Bizarro at Six Flags New England

Six Flags New England

Six Flags New England , formerly Riverside Amusement Park, is a Six Flags theme park, named for the New England region, in which it is located. Located off of Massachusetts State Route 159, Six Flags New England is located less than from the major City of Springfield, Massachusetts, in the nearby...

 are known for their large amounts of air time. In addition, many wooden roller coaster

Wooden roller coaster

A wooden roller coaster is most often classified as a roller coaster with laminated steel running rails overlaid upon a wooden track. Occasionally, the structure may be made out of a steel lattice or truss, but the ride remains classified as a wooden roller coaster due to the track design...

s, such as Balder

Balder (roller coaster)

Balder is a wooden roller coaster at the Liseberg amusement park in Gothenburg, Sweden. It opened in 2003 and was an instant success. Balder has twice, 2003 and 2005, been voted Best Wooden Tracked Roller Coaster in the world in a major international - not because it is the biggest or fastest...

 at Liseberg

Liseberg

Liseberg is an amusement park located in Gothenburg, Sweden, the park opened in 1923. Liseberg is one of the most visited amusement parks in Scandinavia, attracting around 3 million visitors annually. Among the noteworthy attractions is the wooden roller coaster Balder, voted twice as the Best...

, The Voyage

The Voyage (roller coaster)

The Voyage is a hybrid wooden roller coaster at Holiday World & Splashin' Safari in Santa Claus, Indiana, USA. It was designed and built beginning in 2005 by The Gravity Group, with the help of designers Mike Graham, Korey Kiepert, Larry Bill, Chad Miller, and former park President Will Koch; it...

 at Holiday World, and Shivering Timbers at Michigan's Adventure

Michigan's Adventure

Michigan's Adventure is a amusement park in Muskegon County, Michigan, about halfway between Muskegon, Michigan and Whitehall, Michigan. It is the largest amusement park in the state and has been owned and operated by Cedar Fair Entertainment Company since 2001...

 are known for their air-time.

Air-time is caused by inertia

Inertia

Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...

 of the train and the riders. As the train goes over a hill, the mass of the riders tends to resist the downward motion of the ride vehicle, resulting in riders being briefly lifted out of their seats. The amount of airtime caused by a ride is dependent on the velocity of the train, gravity, and the radius of the track transition. Zero gravity is achieved when the downward acceleration is equal to that of gravity, while negative G-force

G-force

The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...

s are caused when the downward acceleration is greater than that of gravity.

Roller coaster enthusiasts differentiate between different types of air-time. Floater air-time is caused by the riders experiencing weightlessness or zero gravity while ejector airtime is caused by negative G-forces.