formula

local lib = {};
-- formula for Mexico uses Wingspan (flight_context) to find the unitRate, unitRate * distance
-- for an aircraft with Wingspan = 33m, the unitrate shall be 5.53
 lib.distance_method = Distance_method.great_circle;
local unitRateFromWingspan = 
     {[16.7] = 0.25, [25] = 1.91 , [38]= 5.53 , [9999] = 8.26 }
      for k,v in pairs(unitRateFromWingspan) do
        if(k>flight_context.wingspan() and v<value) then
            value = v
        end
function lib:calculate(flight_context, route_context, distance)
  return estimate;
end
function lib:estimate(flight_context, route_context, distance)
  return self:unitRateFromWingspan() * distance;
end
return lib;