The short answer
Here is the clear answer.
Santa's reindeer fly through a mix of practice, teamwork, star navigation, and North Pole magic carried in their Christmas Eve harnesses.
Flying begins with practice.
The reindeer train throughout the year. They learn to take off together, turn smoothly, land softly, and keep the sleigh steady in changing weather.
Each reindeer has a place on the team. They listen to one another and to Santa, because a magical flight still needs excellent teamwork.
The harness carries North Pole magic.
On Christmas Eve, silver bells and a specially fitted harness connect the reindeer to the sleigh. The harness helps share the pull across the team and lets Christmas magic travel from the North Pole into every leap.
The northern lights and bright winter stars help the reindeer find their way across oceans and clouds.
Rudolph helps when the sky is difficult.
When fog or snow makes the route hard to see, Rudolph's bright red nose gives the team a clear point to follow. Every reindeer contributes something important to the flight.
Quick North Pole answers
A few more things curious hearts ask
Do Santa's reindeer practice flying?
Yes. They train together all year at the North Pole.
Does the sleigh help them fly?
Yes. The sleigh and magical harness are designed to work with the reindeer as one team.
Why does Rudolph lead?
Rudolph's glowing nose helps the team follow the route when clouds, fog, or snow make it hard to see.