Flight delays and cancellations brought on by weather, technology glitches and other issues offer a lesson: Be prepared and be flexible. Travelers navigate security lines at Louis Armstrong New Orleans International Airport. After a summer of challenging weather and other disruptions, airline passengers have faced many complications.

Frequent storms, the recent air traffic control failure in Britain, a fatal cargo plane crash in Miami, and the chaotic introduction of the Entry/Exit System in Europe are just some of the sources of delays, cancellations and cascading glitches. The industry has grown so rapidly, and millions more people traveling has created friction, said Steve Glenn, the founder of Executive Travel, a corporate travel management company in Lincoln, Neb. One little thunderstorm through the Midwest can hit Chicago, Detroit, Newark and J.

F. K. and take out a day of travel. What wasn't a problem, now we have to plan for.

There's not much travelers can do about circumstances like weather. But they can change their booking strategies to avoid worst-case scenarios. There are a lot of things you can't control, but you can relieve the pain points, said Diana Hechler, the owner of D.

Tours Travel, a travel agency in Larchmont, N. Y. Like defensive driving, defensive flight booking means taking proactive steps to protect yourself, such as padding itineraries, leaving early in the day and potentially spending more for nonstop flights.

Here's what we've learned this summer. 1. Leave a Day Early If you've got a deadline to be somewhere, like a 4 p.m. cruise departure in Barcelona or an afternoon briefing in Cairo before a tour, arriving that morning is often possible, according to airline schedules. But a storm, technology glitches at the airport or other mishaps can all too easily jeopardize the start of a trip.

I advise leaving at least one day early on vacation, Mr. Glenn said. You have to almost assume there's a 50-50 chance you'll be disrupted. Arriving a day in advance also allows you to rest after a long flight and potentially get a good night's sleep before moving on.

And if you are delayed, having the cushion will help you worry less about the deadline. Another reason to arrive early: Your baggage may be delayed, Ms. Hechler said. If you're there the day before, you have an excellent chance of it catching up with you. 2.

Take the First Flight of the Day The control tower for Ronald Reagan Washington National Airport. Air traffic control issues are among the disruptions haunting travelers this year. Booking an early-bird flight gives you more options for later flights should the original be delayed or canceled.

First flights of the day have a more than 10-percentage-point higher on-time performance than later flights of the day, said Anna Brown, a travel expert at Going.com, a service that finds cheap airfares. The advice applies to domestic flights; international departures may only take place once a day. The earliest flights tend to use planes that arrived late the day before.

Should the airline discover a problem, which it would normally convey through an airline alert, morning fliers may have alternatives later in the day, Mr. Glenn said. If you're the last flight, you're pretty much stuck because there are no other options. Ms. Hechler noted that afternoon storms tend to be predictable in summer, so don't plan a trip at 5 p.m. In general, it's a good idea to look for an airline that flies more frequently to your destination. Pick the route that flies a few times a day, not once.

More flights means more chances to get rebooked. 3. Fly Direct When possible, book a direct flight. More takeoffs and landings means the possibility of more complications.

Often a direct option is more expensive than flights that connect. Travel advisers recommend factoring i...