Did airlines make a U-turn on family seat fees?

Several airlines pledged to stop charging families for advance seat reservations. Do you believe them?

It looks like airlines have changed course when it comes to families sitting together. Or have they?

Earlier this week, United Airlines announced with great fanfare that it had changed its seating policy so children under 12 could sit next to an adult in their party "for free." 

Not to be outdone, Frontier Airlines said the next day that it would automati…