Last week Airlines for America released a first quarter recap of 10 US airlines’ performances, along with an optimistic forecast for near-record passenger loads this summer.

It was a tough start to the year for domestic airlines, with the airlines surveyed reporting a net loss of $1.73 billion. Rising fuel costs were a big factor, they were up almost 20% over Q1 2011 and now account for 33% of airlines’ operating costs.

The good news for the air industry? Hordes of passengers are expected to pack planes this summer: 206.2 million travelers are estimated to fly within the US, while 26.8 million will take international flights. But is this also good news for travelers?

Find out how filled flights could affect your travel plans.

Delays will have greater impact. Flying to or connecting in Chicago? The notorious summer thunderstorms now mean more than a few hours delay - with most flights near capacity, you’ll have a much tougher time getting a seat on the next flight to Chicago. Missed your connection by the time you finally got to Chicago? You’ll have the same problem trying to find a seat on the next flight leg.

Budget for checked bags. In Q1 2012, ancillary fees didn’t save the day for airlines as in quarters past because the associated revenue boost is slowing (though airlines are still making nearly $10 per person per flight leg flown). Airlines can anticipate an upswing though - since full flights mean full overhead bins, you’re likely to pay a checked baggage fee at the gate if you aren’t among the first to board.

Don’t count on upgrades at the gate. Want to use your miles to get out of the jam-packed coach section? Not likely, since the airlines are flying near capacity, available business class seats will be few and far between.  You’re better off snagging a premium economy seat if available at booking - they’re made available to frequent fliers first.

The best advice is to anticipate these likely travel disruptions or inconveniences made worse by packed flights, and plan smarter. If you’re connecting through a city with unpredictable summer weather, make sure to leave a healthy gap between flights in case the first one is severely delayed or cancelled.

Elite frequent flier status is key for the chance at better seats if you opt for upgraded seats at booking rather than waiting until the gate, and preferred status will often get your bag fees waived as well as ensuring your bags fit in the overhead bin since you’re in the first group to board.