Every frequent flyer knows this feeling. The seat starts moving behind you and that steady thudding becomes harder to ignore with every passing minute. Flight attendants see this happen on almost every flight and they have figured out what actually works. Their approach tends to resolve things much faster than what most passengers try on their own.
Start With a Friendly Look Back

Flight attendants suggest turning around with a warm smile and making gentle eye contact with the child first. Kids often have no idea they are bothering anyone. A friendly look from the person in front is usually enough to stop things immediately without any words needed at all.
Talk Directly to the Child

Most people address the parent first but flight attendants consistently recommend speaking to the child directly in a calm and friendly tone. Kids respond well to being spoken to genuinely. A simple observation that the seat is connected tends to work faster than most people expect.
Approach the Parent Calmly

If things continue a brief relaxed conversation with the parent is the natural next step. Keeping the tone light and honestly enjoyable makes all the difference here. Most parents had no idea what was happening and were able to write immediately once they found out.
Ask the Crew for Help

There is no reason to handle this alone when flight attendants are right there. They deal with passenger situations constantly and carry a natural authority that makes their involvement effective. A quiet word to a crew member gets things resolved without anything becoming personal between passengers.
Try Reclining the Seat

Reclining slightly reduces the impact noticeably. Not a complete fix but it helps manage the physical sensation while a conversation is being had about it with the relevant people nearby.
Put on Noise Cancelling Headphones

Most flight attendants travel with them on every single flight. They remove the sound component of the experience which takes away a significant part of what makes the whole thing feel so irritating in the first place.
Ask About Moving Seats

When the flight is not completely full there is often another option available. A quick sentence to the crew probably has the effect of a general quick solution of technology that completely eliminates the problem for the comfort of the voyage.
Choose an Aisle or Window Seat Strategically

Booking a seat at the very back row removes the possibility of anyone sitting behind entirely. Flight attendants who travel frequently often choose seats this way on purpose when they want a quieter journey.
Use a Lumbar Pillow as a Buffer

A small travel pillow placed between the lower back and the seat absorbs some of the impact from kicking noticeably. Many frequent flyers carry one anyway for comfort and it doubles as a practical buffer in exactly this kind of situation.
