During a Tuesday-morning flight in April from Los Angeles to New York, Christine Lu’s smartphone web browser loaded an unpleasant surprise: Gogo, the in-flight Wi-Fi provider, wanted to charge her $27 to use its service during the five-and-a-half-hour trip.

The price was more than double the $13 that she had paid for Gogo’s Wi-Fi four years earlier, said Ms. Lu, a start-up entrepreneur.

“It’s like a hotel charging obscene rates for Wi-Fi in the room,” said Ms. Lu, who swallowed the cost to do some work. “You get this bad feeling.”

In the inaugural installment of this new consumer technology feature, we examine the price increases for Wi-Fi on flights from the largest provider of the service, Gogo, and explain why some costs have escalated and some have not, and how travelers can sidestep the worst of the charges.