5 things you need to know about basic economy airfares

1. Don’t expect to suddenly find lower fares than you’ve ever seen. The major airlines have been selectively matching bargain fares offered by Spirit and Frontier on competing routes. That’s why travelers in Phoenix suddenly found $39 oneway fares to Los Angeles last summer on select American, Southwest and United flights. (Spirit started Phoenix-Los Angeles service in April but discontinued it in the fall. The $39 fares are nowhere to be found today.) Airlines are simply now formally offering a Spiritlike fare with Spirit-like restrictions. Until now, travelers who snagged bargain fares got the same amenities as those who paid a higher price.

2. You don’t get a seat assignment until you check in for the flight. Hello, middle seat and separated families. American offers the option of paying for a specific seat but you can’t do that until 48 hours before the flight.

3. You cannot change your flight, even by paying hefty ticket-change fees. So make sure your plans are set or upgrade to the next fare category.

4. Forget about stowing a bag in the overhead bin, except on Delta.