Among fatal plane crashes that occurred during the past 50 ​years, 234 were due to pilot​ error, 77 were due to other human​ error, 156 were due to​ weather, 81 were due to mechanical​ problems, and 475 were due to sabotage. Construct the relative frequency distribution. What is the most serious threat to aviation​ safety, and can anything be done about​ it? Complete the relative frequency distribution below.