Dear Cashing In,

It appears we are in for a busy summer travel season. I have diligently been saving rewards points for a free trip to see family in Detroit but am worried I will not be able to land a desirable time, or maybe not even get on at all. What are the odds of getting a good free seat when summer travel season gets even busier than usual? 

- Imran

Dear Imran,

It sure can be frustrating to be sitting atop a pile of miles or points that you have spent months accumulating and then not be able to use them the way you want.

And you're right: According to the Wall Street Journal, tickets are selling earlier and flights are filling up faster than in previous years. 

For people like you attempting to use miles, that probably means that seats set aside for award travel will also fill up more quickly. That's always true of popular summer destinations, but likely more so this year. The fifth annual SwitchFly Reward Seat Availability Survey, released May 8, showed that showed that many airlines are making award seats more available than in the past, but seats on popular routes can still be hard to find.

When airlines open a flight for booking -- usually around 11 months ahead of time -- they set aside a small number of seats for award travelers. Depending on the size of the plane and the projected popularity of the route, this number could be as high as nine, or as low as zero. In my experience, it's usually at least two or three. 

Those seats often fill up quickly, but the airline can add more if it sees the flight is not selling well. People who book award tickets for a living say they occasionally see award seats added the week before the flight.

If you want to travel this summer and you're not seeing a lot of availability at the lowest award level, your options are limited. You'll probably have to be flexible in terms of dates or routing of your trip, or you'll have to spend more miles than the minimum to secure a seat -- maybe twice as many. 

I just looked at some sample flights to Detroit in July. I don't know where you live or what points you have, but it does not appear to me that flights to Detroit are totally unavailable. You might have to fly in the middle of the week, or make two stops -- such as Richmond to New York to Chicago to Detroit on American Airlines -- but if you have some flexibility that might work for you.

If you see any flights that might work for you, you should book them now. The odds of the availability getting worse are higher than the odds of better flights suddenly becoming available.

Your dilemma is common. Airlines and card companies love to tout the ease of racking up miles, but when it comes to spending them, it's often not so easy.

For best results, book award tickets when they first become available. Of course, that takes planning.

If you're consistently finding yourself in this dilemma of being unable to use your miles, consider a credit card that gives you flexibility in redemption. Just about every major bank has a rewards program that lets you redeem points on any available flight. The number of points is pegged to the cost of the flight. Cash-back cards are probably the simplest to use.

Good luck!

See related: 7 signs you need to cash in your rewards – now!, As airlines merge, frequent flier miles decline in value