In general, when booking your flight to Longyearbyen, September is the cheapest month on average.
From most locations, booking your flights to Longyearbyen around 53 days prior to your departure date finds the best deals.
In general, booking your departure to Longyearbyen for a Thursday represents the best deal on airfare. Try to avoid a Saturday departure to stay away from the highest prices.
On average you can find the best deals on plane tickets to Longyearbyen when looking for flights with midday departure times.