aircraft must be able to withstand one bird collision without yielding or spalling. For the empennage (tail), this is usually accomplished by designing redundant structures and protected locations for control system elements or protective devices such as splitter plates or energy-absorbing material. Often, one aircraft manufacturer will use similar protective design features for all of its aircraft models, to minimize testing and certification costs. Transport Canada also pays particular attention to these requirements during aircraft certification, considering there are many documented cases in North America of bird strikes with large Canada geese which weigh approximately on average, and can sometimes weigh as much as . At first, bird strike testing by manufacturers involved firing a bird carcass from a gas cannon and sabot system into the tested unit. The carcass was soon replaced with suitable density blocks, often gelatin, to ease testing. Current certification efforts are mainly conducted with limited testing, supported by more detailed analysis using computer simulation, although final testing usually involves some physical experiments (see birdstrike simulator). Based on US NTSB recommendation following the 2009 US Airways Flight 1549, the EASA in 2017, followed a year after by the FAA, proposed that engines should sustain a bird strike not only on takeoff and climb where turbofans are turning at their fastest, but also in descent when they turn more slowly; new regulations could apply for the Boeing NMA engines. Wildlife management Though there are many methods available to wildlife managers at airports, no single method will work in all instances and with all species. Wildlife management in the airport environment can be grouped into two broad categories: non-lethal and lethal. Integration of multiple non-lethal methods with lethal methods results in the most effective airfield wildlife management strategy. Non-lethal Non-lethal management can be further broken down into habitat manipulation, exclusion, visual, auditory, tactile, or chemical repellents, and relocation. Habitat manipulation One of the primary reasons that wildlife is seen in airports is an abundance of food. Food resources on airports can be either removed or made less desirable. One of the most abundant food resources found on airports is turfgrass. This grass is planted to reduce runoff, control erosion, absorb jet wash, allow passage of emergency vehicles, and to be aesthetically pleasing (DeVault et al. 2013) However, turfgrass is a preferred food source for species of birds that pose a serious risk to aircraft, chiefly the Canada goose