WebMD says that
Parents have relied on pacifiers for ages to calm crying infants.
However, pretty much every time I fly in an airplane, there is one child screaming (and screaming) a few seats away. I've never heard children starting to scream and stopping (or toning it down) after a minute or two, as if the guardian(s) used a pacifier. Do pacifiers not work on planes? Do the parents just not care (hard to believe)? Do they not know about pacifiers?
Pacifiers aren't magic. If something else is bothering a baby, a pacifier only calms them for a short while. This is useful, for example, if you need a baby to calm down for a few minutes while you fix a bottle, but you have to address the underlying need in short order or the baby just spits the pacifier out and gets madder than ever.
On plane trips, there are a lot of things out of the control of both parent and child. It's loud, it's bright, your schedule is all off, there are lots of new people around, you can't get out of your seat at certain times to change a diaper or whatever, you can't sit or lie in your most comfortable positions, and even with sucking, your ears hurt from the pressurization. Pacifiers only help if all the other conditions happen to be just right.
I fly a lot, and have done for the last 40 years, and while there is the occasional inconsolable baby, most flights are relatively peaceful. Even crying babies are often soothed, but they usually want cuddles rather than a pacifier, and cuddles can be tricky at takeoff and landing.
When my kids were young we found a pacifier or a bottle did help a lot, but if they had sore ears (during descent babies don't know how to equalise pressure) or had their sleep routine thrown off because of many hours of travel what they really wanted was to be held and rocked. So we'd use a pacifier and distraction techniques to get them through the worst bit, so as not to annoy other passengers, and it really did work well. A couple of minutes of loud crying at most, and generally able to be calmed down into mild grumbling.
Not every baby takes a pacifier. While they may be magical devices for the little ones who will, some simply refuse them. My son has never liked them - he'd take it for less than ten seconds and then kick it out.
Additionally, some parents avoid them for their own reasons. Some of these reasons are backed in science, others are not. In general, there are some limitations on pacifiers -
There is more info on the site linked above if you care to see.
I'm sorry that your flight was unpleasant but, unfortunately, a spare pacifier in your pocket probably isn't a solution. If the baby takes a pacifier, the parent probably already has one and uses it and if they don't take it or their parents don't allow them, the one you have on you is unlikely to convince the baby that they're great or the parent to use it.
No, pacifiers don't always work.
Using the pacifier too many times when the baby clearly doesn't want it and you will actually increase the crying.
It's usually obvious when the baby doesn't want the pacifier. The baby will open his mouth to drop the pacifier. The baby will wriggle his head out of the way of the pacifier when you try to give it to him a second time. The baby will cry like it's about to be murdered when it sees the pacifier (this will usually happen on your third or fourth attempt). And in some cases if the baby has enough dexterity, the baby may even take out the pacifier and throw it on the floor, and then give you an evil stare -- all the while continuing to cry its little lungs out .
Usually, a mother will know what's bothering the baby depending on the actual cry of the baby. If the mother doesn't know, she can just try different things until the baby stops crying, or until the baby cries itself to sleep.
In the case of an airplane, the crying is usually triggered by the change in pressure which causes pain to the baby. And here is the official advice given for that:
http://kidshealth.org/en/parents/flying-ears.html#
But even implementing that advice (which includes using a pacifier and other tips) from the second page doesn't guarantee that it will always work.
To paraphrase the question:
The answer:
The assumption 1. is wrong.
