The Air Travel Answer Lady is here to help. Just send your queries to "Dear Airy," and she will favor you with a reply. Dear Airy:

I am taking a flight from Washington to Atlanta. We've been sitting on the runway for four hours. How do I know if I will have enough air to breathe until we take off? -- Patty Faye Dimetres Dear Patty:

Four hours is not too long a time to wait on the runway these days. What I always do for my own safety is carry a canary in my pocket. When the canary keels over dead I know it's time to slide down the emergency chute. Dear Airy:

I was told I could fly to San Francisco for $99. But when I arrived at the airport I was informed that particular fare was only good on Columbus Day. I asked them if they had any other bargains, and they told me they had a red-eye special to El Paso with intermediate stops in Charlotte, N.C., and Billings, Mont., for $355. Is someone giving me the business? -- Jane Cohen Dear Jane:

Your airline is only charging you what the market will bear. Thanks to deregulation its fares must compete with the other carriers on the same route. This is how the fare-war works: The various airlines announce bargain tickets for the same destination, which are sold out just as you get to the counter. You then have the choice of paying the regular fare or canceling the flight, which carries a penalty of five years in prison. Dear Airy:

Are there any regulations spelling out the width of seats and leg room on American carriers? -- Philip and Myrna Aiello Dear Philip and Myrna:

There are strict rules concerning the transport of pets and domestic animals in flight, but they do not apply to humans. For example, pets are not required to eat airline food, but human passengers are. The reason for this is the FAA knows every pet is dear to someone. But the government still considers human beings to be excess baggage. Dear Airy:

When the flight I'm on has a near miss in the air, do the people on my plane wave to the passengers on the other plane, or should they wave to us? -- Kay Roberts Dear Kay:

In a near-miss situation either side may wave first, but only the pilots can make rude gestures with their fingers. Dear Airy:

Why do you see so many little kids flying on planes these days? -- Kathy Bye Dear Kathy:

More children are flying now than ever before because it's cheaper for a mother to travel with her kids than put them into a day-care center.

Most of the mothers you see on planes have no particular destination in mind and are just killing time until their husbands can take them to Burger Chef for dinner. Dear Airy:

Do airborne pilots get extra pay for telling you what cities you are flying over? -- John R. Proffitt Dear John:

No, they are all volunteers who delight in giving a tour of the earth at 40,000 feet. These pilots believe a passenger will lose his sense of awe if he doesn't know he has just flown over Topeka, Kan.