Risk Assessment of Outdoor Airport Workers Exposed to Lightning

Lightning is a hazardous and potentially fatal threat to those working outdoors. This is a major concern for personnel servicing aircraft at airports. For safety reasons, airport and airline operators will bring workers inside any time lightning is detected within a critical distance. Workers will remain indoors until the lightning threat has passed, which causes operations to halt for the duration of a direct thunderstorm impact. The challenge for airlines is to find a balance between personnel safety and operational efficiency. Clearly, being overly safe yields operational inefficiency causing flight delays that can propagate through an airline's schedule and end up costly for the airline. On the other hand, ignoring the lightning threat may result in injuries or worse.

This study aims to quantify the risk of people working outside while exposed to a lightning threat for one airline operating at a major US airport. Such exposure may occur due to imperfect implementation of lightning safety procedures, but also due to incomplete lightning information that may not reflect all of the lightning threat present. The latter poses a risk that may not be known to the operator, while the former represents a risk that should have been recognized given the lightning information at hand. The unknown risk can be characterized by comparing the operationally used lightning data to comprehensive lightning information obtained by more advanced research-quality networks; however, such lightning information is typically not accessible for airline and airport operators.

In this study, the airline's actual ramp closures were compared to nominal closures (i.e., perfect implementation of safety procedures) based on minute-by-minute data of the airline's operationally used lightning information to identify periods of known risk. Similar data of a comprehensive lightning source was also used for comparison to identify unknown risk periods, and subsequently a risk analysis of workers outdoors during these periods was performed. Utilizing actual and scheduled aircraft arrival and departure times, the number of people servicing aircraft during periods of risk was estimated. With information about the lightning activity during these periods, the estimated number of people at risk, assumptions about the chance of someone getting injured by lightning and the fraction of injured people that may die from their injuries, plus using industry-accepted values for the cost of injuries and fatalities, the lightning risk can be quantified. Accordingly, the risk for each period of lightning exposure was quantified and expressed in terms of monetary costs.

The potential costs associated with the risk of airport workers exposed to lightning threats were estimated for several cases from the summer months of 2014. The outcome of this analysis revealed that the lightning exposure risk carries a significant cost, although the estimation approach is notably uncertain. The costs associated with the lightning risk can be contrasted to the costs associated with flight delays that would have occurred had workers been safely inside. This manner of analysis may provide a basis, at least from an economic point of view, of how to balance safety procedures with operational efficiency concerns.