Virgin America now allows you to add your pet to your on-line reservation, “either during booking or by clicking ‘Anything Else?’ when viewing your itinerary.” That’s rare — of the major U.S. airlines, only Continental has a similar system in place (Northwest used to).

I hope more airlines will follow suit, since it makes all kinds of sense. Otherwise, you have to either make your own reservation on line, and then call quickly to add your dog (gambling that there will be room on the plane for her); or you have to make your entire reservation over the phone, which is time-consuming and may entail a service charge (unless you can convince the service representative to waive the fee, on the grounds that you were forced to call because you’re traveling with a pet).

Here’s what you do: Tell the site when you want to fly, where you want to go, and choose the flights that work best for you. Choose the seats you want. Give Virgin America the contact information and personal data they require. When you reach the “Enter Payment Information” screen, you’ll see a list of extra charges, starting with travel insurance. The second item is “Traveling with a Pet?” Click on the “Expand” button, check the box under each flight segment (indicating that you agree to VA’s rules and fee), and click “Apply Pet.” The pet fees appear in the resulting invoice under “Extras.” I suggest printing the receipt they offer you and adding it to your travel documents, so that you have proof in hand that your pet’s reservation has been made and paid for.