We used to have the occasional daring bicyclist, then suddenly we had warrior bikes bearing down on pedestrians and taunting motorists.

We had lousy drivers and accidental accidents, and now we have road rage and deliberate accidents.There was always the odd airline passenger who was driven to rudeness by drink or delays or delayed drinks. Now the numbers have increased exponentially, to the point where one of the routine hazards of flying is air rage.

Passengers attack flight attendants. They attack one another. They attack crew members and other passengers who are trying to restrain them from continuing the original attacks. Some American airlines have said that the amount of airborne violence has doubled, while some European ones estimate that theirs has quadrupled.

What's next? Rocket rage on the part of crazed astronauts?

What is happening to our transportation system, Miss Manners wonders. Why don't people just stay home until they feel up to the inconvenience of moving around?

As always, explanations for bad behavior are plentiful:

Flying is stressful.

Allowing drinking stimulates people who might otherwise be able to restrain themselves.

Banning smoking eliminates a relaxation that might otherwise enable people to restrain themselves.

The food is bad. There is not enough of it.

Seating is crowded. Overhead bins are crowded.

Flights are delayed. Luggage is delayed.

Service is scant. Employees are not specially trained to deal with people on the brink of going bonkers.

Excuses are available for everyone. If you didn't get one, please let us know by ringing the call button.

But if all passengers have reason to go haywire, why don't we recognize that we are running lofty loony bins and install straitjackets where we now have mere seat belts?

Miss Manners doesn't like airplanes any more than anyone else. They are perilously subject to whims of weather and traffic and notoriously lacking in basic amenities, such as fresh air. If the places she likes to go were within easy reach by swan boat, she would never bump down one of their aisles again.

Furthermore, she resents the no-win choices they offer: Carry your own luggage aboard and compete for storage space, or check it and sacrifice both time and peace of mind; sit up awkwardly or lounge back into the scant space of the person behind you; eschew minor comforts or pay for them outrageously.

Nevertheless, there is a reason that Miss Manners and most other passengers do not have to be restrained by force. Civilized people are supposed to recognize that discomfort and other provocation are not an excuse for being rude. They are conditions that demand more attention to politeness, not less.

Without that principle, one could find an excuse for being rude on even the most luxurious of voyages. Which, come to think of it, is probably what is next: Cruise rage.

Dear Miss Manners: I just discovered a credit on my credit-card statement -- a person I thought was a friend had returned the item that I sent to her as a gift.

She didn't bother to call first to express her desire to return the gift. She didn't even send a note. I'm appalled and consider her behavior rude. It wasn't the return of the gift that hurt me, it was finding out via my credit-card bill.

Gentle Reader: How did you want to find out? Through a note that said "Thanks for trying, but I hate what you picked"?

It's not that Miss Manners disagrees about there being a problem here. People who are generous enough to select and give presents should not find out that they have failed. She only disagrees with your solution, which was aimed in exactly the wrong direction.

Your friend should have disposed of the present without your ever finding out about it. After thanking you without reservation, she could have given it away, exchanged it or accepted the return credit herself. Miss Manners prefers to think that she thought she was doing so when the company mistakenly credited you, and she advises you to believe the same.

Judith Martin is the author of "Miss Manners Rescues Civilization" (Crown). Judith Martin, Dist. by United Feature Syndicate Inc.