‘It flies itself’, said no helicopter pilot, ever. Piloting a helicopter is a complex, continuous, multi-task operation, in no small part because of helicopters’ inherent and dynamic instability. This means helicopter pilots face a high workload in day-to-day flying, with a peak workload in hovering. In her 2008 publication Human Performance, Workload and Situational Awareness, human factors specialist, Dr Valerie Gawron, says the ‘workload of a helicopter pilot in maintaining a constant hover may be 70 on a scale of 0 to 100’. Rotary-wing wags have an earthy but arresting description saying the same thing: hovering is ‘like making love in a hammock standing up’.

The US Federal Aviation Administration (Advisory Circular 23.1523) defines workload as ‘the relationship between an individual’s capacity to perform a task (mental and/or physical) and the level of system and situational demands associated with the performance of that task. Tasks that demand much of the human resources (capacity) are high workload tasks. And importantly, ones that demand little human capacity are low workload tasks.’

There are various ways of measuring workload, including the Bedford workload scale and the NASA task load index (TLX) based on pilots’ subjective evaluations of their workload. Objective measurement includes data on pilot behaviour such as the time taken to perform a task, error rates, and the number of actions performed; as well as sensorimotor activity (eye-tracking, number of head movements) and physiological measurement via electrocardiograms (ECG) and respiration rates. The chief problem with such data is that it is mainly gathered from simulator flights, and therefore subject to the limitations of scenarios not being ‘real’.

Given the inherent instability of helicopters, rotary pilots have a greater than average workload, but according to David Lamb, a test pilot and rotary specialist with CASA, many helicopter pilots do not have a good understanding of workload, the consequences of increasing workload, and what this workload means for their safe performance. They see it as a challenge and a deficiency in their own ability. Their tendency, Lamb says, is to ask ‘“What’s wrong with me?” They see such issues as a function of their inability to complete the task, rather than considering workload as an extension of the flight envelope of the aircraft, for which there are defined limits’.

Just as there are manufacturer-defined limits to safe flight—the physical limits of structural, aerodynamic, powerplant, transmission or flight control capabilities—so Lamb says, helicopter pilots should consider workload in the same light. They should ask themselves, ‘What spare capacity do I have to cope with the unforeseen and unexpected?’ Unfortunately, ‘when you go into the red, there is no gauge to tell you that’.

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