When the airport clerk hefted a suitcase off the old-fashioned scale, its platform jiggled and squeaked.

"There's no room for your bag, madam," the pilot said after noting the weight.

We were in an open-air hangar next to a dirt runway in a Costa Rican jungle.

"But I bought a seat for it," the middle-age passenger said.

"Well, OK. It can go and you stay," the pilot countered good-naturedly. "Your bag is too heavy for the plane. We'll bring it on the next flight."

After some dickering, the woman — without suitcase — and two of us with small carry-on bags folded ourselves into the cramped, single-engine plane.

That day several years ago, the woman with the large bag had two choices.

Today, her options on a small plane would be the same. But on a large commercial airliner, she would have a third option: buying her way out of the dilemma.

Doing so can be costly. Airlines are paying more attention than ever to baggage weight and size, and charging for pieces that are too heavy or too large. Limits for carry-on and checked luggage vary with the airline, so you need to check.

The basic size guideline for carry-ons is 45 inches for combined depth, height and width. Weight is more of an issue with checked bags. Limits on domestic flights start at a maximum of 50 pounds per bag, with a two-bag allowance. Limits on international flights are lower.

The easiest way out of the dilemma is to pack light. You save money and make life easier for everyone by having less stuff to manage.

Traveling light with carry-on luggage is not tricky, but it takes planning. You need a list.

To pack for two to three weeks using a carry-on bag and a small day pack means accepting one premise: Less is more.

Sacramento, Calif., packer extraordinaire Janis Jacox has a nugget of wisdom she shares at her packing demonstrations: "Don't think of your trip as three weeks. Think of it as a five-day trip and wear the same clothes."

Using that philosophy, it's easy to fit everything into a carry-on. Some people roll their clothes, some swear by packing in layers, and others like the container method.

Jacox packs in layers with a bundle. So does Jon Holloway of Holloway Travel Outfitters, a travel store in Sacramento. About once a month he demonstrates his technique in a free seminar at the store.

Jacox and Holloway say their methods reduce wrinkles.

Now, let's get personal. I have traveled all over the world on two- and three-week trips, all with a single carry-on bag. In 1979, I journeyed overland for four months, from London to Nairobi, with just a small duffel bag and a sleeping bag. My packing tips are drawn from those experiences.

Generally, I roll my clothing and space it around hard items, such as shoes and books, a method that makes it easy to pull out just one thing at a time.

Page O'Connor said Holloway's packing demonstration changed the way she packs. She attended a seminar just before traveling to France and Italy for three weeks.

"I used the roll-it theory years ago," O'Connor said. "This time I put the pants in, alternating side to side, laying tops in different directions. It made a neat package and worked out really well."

Packing guru Jacox starts her layers by putting hard things — books, hair dryer, shoes and anything metal — on the bottom and laying the clothes so they fold over softly and make a pillow-size bundle.

"That way, if you have to have a complete search (at airport security), you can lift the bundle out for scanning. I had a complete search in Houston, and it took 35 seconds," Jacox said.

To pack light, consider what you need — not what you might need. Whether crossing the Sahara or visiting Paris in February, come up with a few mix-and-match clothes in a basic color scheme that will carry you through with style.

Unless you're meeting the queen, you can go just about anywhere with a good-quality black or white T-shirt by adding (faux) pearls. For men, a black turtleneck works.

Packing light also means you'll be washing out your undies nightly, and your quick-dry pants and/or shirt every few days. Several companies use quick-dry fabrics, including Ex Officio and Royal Robbins. Their clothing is available at travel stores and online. (Laundry tip: Shampoo with conditioner works great.)

First, the basics.

To get started, make a standard list that you can adjust for each trip, depending on destination and weather. One to consult is posted on the Web site www.onebag.com. It's full of ideas. Consider storing yours on your computer, so you can adjust and print it before each trip.

In general, I take two pairs of lightweight pants, one black and one dark khaki, each with a zippered security pocket. I also pack one long, slinky skirt (black). In winter, I add black tights.

To go with them, I take two long-sleeve shirts/blouses (blue, also in lightweight fabric); three T-shirts (white, black and blue); a black cardigan; and a rain shell that rolls up into a stuff sack about the size of a can of tennis balls. I also pack two sets of underwear and two pairs of socks (more in the Third World, where they're hard to replace), both in quick-dry fabrics (Fox makes the ones I wear). For cold weather, I add a long-sleeve silk undershirt that's pretty enough to peek through at the neckline.

This wardrobe goes anywhere and everywhere. No one even notices my clunky, wear-everywhere shoes. I take two pairs, a low-cut hiking shoe and closed-toe black flats (or low-cut black boots in winter).

For the trip to Paris in February, I would add a long raincoat with a liner, which I would wear on the plane; a black fleece hat; gloves; a wool scarf; and long silk underwear, or tights, for warmth.

For crossing the Sahara, I would add a pair of jeans and seal one set of clothes in plastic to put on at the end of the journey while everything else goes to the laundry.

Also, for conventional travel, I wear a small, black vest with an inside security pocket. It's better than a purse. The vest has multiple pockets for local cash, a tiny flashlight for dark restaurants and stairways, emergency TP, lip balm, a comb, sunglasses and hard candy for hungry moments.

Also on my standard list are a reading light, toiletries (sample sizes), two blow-up hangers (for drying shirts), elastic clothesline, medications, one novel and a guidebook.

The convenience of carry-on comes with a few compromises: No pocketknives, scissors, corkscrews and other sharp things. If you plan to carry on your small bag, then just purchase what you need at your destination — you're not going to the moon. Even in Tamanrasset in the southern Sahara, I found hand cream and shampoo.

Another consideration for what you put in your carry-on is weight: Can you lift your bag into the overhead bin? You might take a practice spin around the house with your packed suitcase.

What about jeans, you ask? Well, it used to be that jeans were not acceptable, but now they are everywhere. On a recent trip to Prague, Czech Republic, more city residents were in jeans than were visitors. Jeans do not dry overnight; on the other hand, when it comes to dirt, jeans are forgiving (and, when necessary, coin laundries or hotel service help out).

To keep your standard packing-light list up to date, take a moment when you get home from your trip to note what you did not use and what you should have taken. Don't count on your memory; it's already overpacked.

E-Mail: jgreen@sacbee.com