Frequently traded models are updated as soon as they begin to show variation from the previously published values. At the end of each quarter HeliValue$ reviews all models covered in the Blue Book to ensure overall accuracy. Resale pricing adjustments are based on actual sales transactions and current market conditions such as overall trends in asking prices, increase or decrease in supply, demand, and sales volume. We obtain resale pricing data from owners and operators, lenders and lessors, brokers and equipment manufacturers worldwide.