Climb
From just after liftoff to the cruise level. High thrust, high workload, close to the ground for the first part of it.
The initial climb offers little height to trade for time, so failures here concentrate the crew's options. This is where engine failures, configuration problems and terrain proximity on a departure procedure become critical.
Related terms
Takeoff
From the start of the takeoff roll to a few hundred feet above the runway. Statistically one of the two most dangerous parts of a flight.
Cruise
Level flight between climb and descent. The longest phase and the one with the fewest accidents per hour.
Loss of Control In-Flight (LOC-I)
The aircraft departs from normal controlled flight: a stall, an upset, or a control problem the crew cannot recover from.