Helicopters don’t always take off vertically or straight up for several reasons.
Although they are capable of vertical take-offs, pilots prefer to transition into forward flight as soon as possible, especially when clear of obstacles. This is because a vertical take-off requires more power and increases the risk if the engine fails, leaving less time and space to recover safely.
Forward flight at low altitude allows for a quicker response in case of emergencies, such as entering the "dead man's curve", a flight envelope where safe recovery from power loss is challenging.
Additionally, transitioning from hover to forward flight helps achieve translational lift, which improves efficiency and reduces power requirements.
