Because to break an arm requires either a considerable amount of force or asharp impact. A typical airliner cruising at altitude is doing 400kts. You would not be able to hold your arm perpendicular to the airstream but it would not break. After a short period your arm would become frozen and your skin would start to break off.
Sounds like it could be a problem with your brake light switch mounted on the arm of your brake pedal under the dash.
Follow the brake pedal up behind the dash. The pedal arm ususally operates a button that turns on the lights when the pedal is pushed. The button could be stuck.
stick it up
brake her arm
stick
yes, of course it does i just broke my arm today
Check the sensor on the brake pedal arm.
It's attached to the brake pedal arm.
yes
bad or out of adjustment brake switch on the brake pedal arm
It's on the arm of the brake pedal.
On the brake pedal arm.