During a descent from 6,000 feet MSL, after passing a 5,000-foot MSL checkpoint verified by GPS, the altimeter reads approximately 5,600 feet, the VSI indicates a 200 fpm descent, and the airspeed indicator shows 10 knots higher than normal. All other instruments appear normal. What is the most likely cause?

While climbing from 4,000 feet MSL, you observe that the altimeter remains fixed at approximately 4,000 feet, the vertical speed indicator shows zero, and the indicated airspeed is lower than normal for the power setting and pitch attitude. The most likely cause of this indication is