When you fly, can you carry on your climbing gear?

—Stevemoorehead via rockandice.com

Depends on what you mean by “climbing gear.” Ice-climbing hardware such as tools, screws and crampons will have to be checked, as will any weapon-like implements such as nut tools and shivs. These items are allowed in checked baggage, though you will pay $25 for the first bag and $35 for the second (Southwest does not charge), each way, and bags heavier than 50 pounds or oversized can cost up to $150 extra each way. The latter point makes buying a crash pad once you arrive at your destination, then leaving it there, more economical than flying with it.

Soft goods—ropes, harnesses, shoes—will be fine to carry on, and most airlines let you stow one bag in the overhead for free, which is, I imagine, the reason for your question. Hardware (belay device, nuts, cams, carabiners) should be allowed as carry on, but could single you out for some special loving treatment, as the TSA is suspicious of devices they don’t understand.
Items you can’t carry on or even check, ever, are ones that could go bang, such as propane canisters and white gas for your cook stove. You might be allowed to check your white-gas stove if it is drained and doesn’t smell like gas, but it could still be confiscated. Go to www.tsa.gov for the complete list of prohibited items. Next!