Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
21 Survey participants were asked to identify the kind of problems they have encountered at airports relative to reduced visibility, seeing where they are on the airport, or the difficulties in nav- igating on the airfield when engaged in snowplowing, broom- ing, deicing, or other winter operations. They were then asked to identify how they solved the problems. Their responses, as noted here, provide insight into the varied operations of dif- ferent categories of airports that have varied organizational structures and resources. VISIBILITY All snow events present some measure of degradation in vis- ibility and SA. Blowing snow, whiteout and blizzard condi- tions, blowing sand, heavy fog and precipitation, equipment blocking line of sight, and vehicle blind spots were factors cited by operators as affecting visibility. Outside the vehicle, the accumulation of snow or snow banks obscuring signs and lighting are major issues. The speed of vehicles was cited as an issue by several air- ports because it resulted in both accidents and incursions. The time pressure to get the movement area cleared prompted the drivers to push their limits and the limits of their vehicles. Unfortunately, higher speeds decrease driver reaction time and increase braking distances, which increase the collision risk factor on the airport. The use of runway and taxiway lights generated contra- dictory statements from operators as to which was the best method. One large-hub airport always works with their run- way lights at high settings so they can better see the airfield signs that are connected to that circuit. However, a driver from a small-hub airport commented that the runway lights are always very bright, even on the dim setting, making it hard to cut the edge very close because of the glare and disorien- tation in the peripheral vision. One non-hub airport operator requests that the runway lighting be turned down, but not off, so that drivers are not blinded by the intensity of the airfield lighting. In contrast, the procedure at another airport is to turn off the runway lights as a means to eliminate confusion to pilots and reduce the risk of aircraft use. However, the lack of runway edge lights compounded the lack of visual cues for the snow crew. To illustrate how limited visibility and poor lighting can be confusing, one operator described a situation where a driver lost track of which side of the runway light he was oriented toward and ended up driving into the safety area. Having a Category II/III instrument approach with center- line lighting and touchdown zone lighting makes it easier for a vehicle operator to discern the borders of the runway and oneâs position on the runway; however, most airports do not have such capability. Finding either the runway centerline for a beginning snow run or the sides of the runway or taxiway is a problem during winter operations because the pavement markings and lighting may be obscured. Using the obstruction lights on the localizer for a position reference on the runway was a trick one operator used. Another operator used obstruc- tion lights on buildings or other fixtures as a reference. MANAGING ENVIRONMENTAL CONDITIONS There were a number of suggestions made by survey respon- dents regarding the most effective way to manage or address the problems brought on by wintry conditions or low visibility. To help with visual orientation, snow sticks mounted to edge lights are a common practice. Installing radius stakes around taxiway curves before winter season helped on several airports. One airport put reflective tape on the ends of signs as a way to help see where the signs are and for enhancing situational positioning. However, locating signs or edge lights proves difficult when, as another operator pointed out, the snow is so deep you cannot see either signs or lights. One airport operator commented on the benefit of runway guard lights, which is an available technology mentioned in chapter ten: Above ground runway guard lights (RGL or commonly called wig-wag lights) should be mandatory at all runway/taxiway inter- sections. In-ground lighting and surface markings are often obscured during snow/ice events. Compacted snow and ice can render those aids unusable for days following an event. Several operators said the key to not having an incident, incursion, or collision with another vehicle is simply to slow down the operation as visibility declines. Maintaining proper distance from other vehicles was important and lighting on the rear of vehicles helped that purpose. This is supported in the literature search (35). We lead our snow teams with our most experienced operations staff. Most of the staff have over 20+ years working on the air- field, and they always know where they are. We also have the latest equipment with our runway snow teams. These vehicles are lit up like a winter holiday, and are easily seen in poor visibil- ity conditions. They also have the best deicing capabilities like heated windshields, etc. CHAPTER FOUR ENVIRONMENT
If the visibility gets too poor, several airports stated their policy is to stop snow removal operations until conditions improve. âPull the operators off in low visibilityâmanage the risk,â was the lament of one operator. When encountering a whiteout condition, one airportâs practice is to stop and stay in position until it has passed. This requires good communica- tion with other vehicles and with the ATCT, if in operation. In this case, the vehicle operators would all call in their positions to the designated supervisor or to the ATCT for runway evac- uation instructions. If occurring at an uncontrolled airport, the risks must be evaluated beforehand as to what actions will be taken. For example, the point at which one airport ceased snow operations was the visibility reaching a trigger point of 300 ft RVR; for another, operations stopped when visibility was one-eighth of a mile (approximately 600 ft RVR). The nature of wintry conditions makes it difficult for oper- ators to see where they are located on a surface. It also makes it difficult to judge their distance from other vehicles or even the presence of other vehicles. Determining the best methods or procedures for working in these conditions is difficult because of the various operating capabilities and characteris- tics of the airport and its employees. The operational variabil- ity means that each airport needs to evaluate in more depth its exposure to risk. The implementation of an SMS can help in this evaluation and provide guidance for each operator. 22 An SMS is a formal, top-down, business-like approach to managing safety risk. It includes systematic procedures, prac- tices, and policies for the management of safety (including safety risk management, safety policy, safety assurance, and safety promotion) (36). SUMMARY Chapter four discusses the effect of winter environmental con- ditions on collision risk factors such as driver visibility and the absence of visual cues for snow removal efforts. The speed of vehicles was deemed to be a collision risk factor because higher speeds decrease driver reaction time and increase braking distances. Suggestions are made for the use of snow sticks and reflective tape to assist in recognizing positional placement. Consensus did not exist on whether runway lights should be on bright, low, or off when conducting winter oper- ations. There were various comments received supporting each arrangement. Nor was there agreement on what to do during poor visibility conditions; that is, whether to stop in position on the runway or to pull all the vehicles off the oper- ation until conditions improved. Because of the variability of operations at airports, it is suggested that each airport imple- ment an SMS to evaluate their procedures in more depth. An SMS is one avenue for accomplishing proper evaluation, as is pre- and post-season review of the SICP.
