Speed Question A Plane and a Football

Imagine your on an airplane at 35,000 feet traveling at 300 miles per hour

You and your friend get up from your seats. Your friend goes to the front of the airplane, you to the tail portion of the airplane with a foot ball.

You toss the football and lets say it travels at 5 miles per hour

Does that mean that the ball to an observer on the ground is really traveling at 305mph, but the other passengers only see it moving at 5mph?

if the plane is transparent then yes