Do airlines withhold seats to boost premium sales?

Why are so few economy seats visible when you try to book?

Fliers often find that when they buy tickets they see that none or very few of the cheapest seats are available, only to later board a half-empty plane. When asked, airlines provide few details. But, the theory goes, carriers are deliberately displaying only a few of the economy seats available on various flights in the hope fliers will pay for the privileged but far pricier premium seats. The alleged practice is especially annoying, for example, for families and other passengers who want to sit together.
The constituent parts of yield management databases that make up airline and travel booking screens is, of course, off-limits to consumers. But some industry experts claim to have inside knowledge.
“They’re trying to get people to buy premium seats,” says newspaper columnist and founder George Hobica. “They want to increase revenue. And we’re getting more complaints about it.”
USA Today
[pictured: British Airways self-service check-in; courtesy oneworld]