Helicopter Flight Information

Confined Area Operations

This is a high risk area of operations where several different techniques are often taught. In this article, we will talk first about the proper departure technique(s) and also another technique which is often taught but profoundly improper and unsafe. In the later part we will talk about approach techniques. Pilots should be well aware of the hazard of Settling with Power during approaches to confined areas.

The figure to the left depicts the safest technique when steady but slow airspeed is used and steady and constant power is applied. The helicopter should be flown on a path which will safely clear the obstacle and also that which will allow a stop safely short of the obstacle if the obstacle can not be cleared. 

The pilot must be aware that if an abort becomes necessary, the helicopter must be slowed to a stop into the wind well short of the obstacle. As the helicopter comes to a stop, a minimal sink will occur (the red line) as any gained translational lift is lost. The helicopter will settle to a high hover at which time it must be flown rearward to the point of departure where it must be reconfigured for another attempt. Changing to the zoom-and-climb technique is not an acceptable option however an attempt at the vertical climb method is an option but the best option is to remove cargo or fuel.

It is never acceptable to do a pedal turn to abort a confined area departure. The only acceptable abort is to fly the helicopter rearward to the point of departure. It is always wise to reposition the helicopter to the rearward most safe location in any confined area to allow the longest forward movement for the departure.

This figure depicts a departure profile which may be used to depart a very tight confined area. This is the technique most commonly used by EMS pilots to exit the many tight scene areas which they land in. The danger of this technique is that the helicopter is lifted vertically into the HV curve but in a stabilized and safe climb after a power check has been accomplished.

Flying under the wires is not a safe option. The obstacle could be just about anything, trees, buildings, etc. If sufficient power can not be achieved to clear the obstacle, the helicopter can simply be landed back to the point of departure for reconfiguring.

In the event that a departure can not be made as in the profile depicted in the first figure above, a departure using this technique is an option. If a departure can not be accomplished using either one of these methods, then the only remaining option is to reconfigure the aircraft.

The figure to the left depicts a common but very poor and unsafe confined area departure technique. This is the zoom-and-climb technique which really needs no other description. This technique is unacceptable for several reasons.

1- As the helicopter is pulled into the cyclic climb, translational lift gained while zooming toward the obstacles is lost at a very rapid rate and a sink can develop as this lift is lost especially with a heavy aircraft. This could result in either a crash into the obstacle or an over-torque in an attempt to avoid a crash.

2- A cyclic push-over is necessary at the top of the climb to regain lost translational lift. Although an experienced pilot may do this gently to avoid a mast bump, a less experienced pilot may not.

3- As the helicopter is accelerated forward, it may be flown into the down-flow of air over the obstacle caused by the wind passing over the obstacle. This airflow is invisible but must be know by, and visualized by the pilot.

This figure depicts two different approach profiles either of which is acceptable. Neither has an advantage over the other however the difference is that following the blue line you will spend a longer time deeper in the HV curve while along the black line although you will not be as deep in the HV curve, if you loose your engine you will be snacking on trees.

Following the black line, the helicopter is slowed continuously until the steeper angle is intercepted at an airspeed which permits continuation of the approach. Most importantly, once the final approach profile is reached, the three conditions conducive to Settling with Power must be considered and not less than one condition must be eliminated. Those three conditions are: 20% or greater power applied, airspeed less than ETL (often taught 10-knots or less), descent rate of greater than 300-fpm. The only condition that can be eliminated is the descent rate which absolutely must be less than 300-fpm before the aircraft is slowed to less than ETL.

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Last modified: 08/24/10