If while in level flight, it becomes necessary to use an alternate source of static pressure vented inside the airplane, which of the following variations in instrument indications should the pilot expect?

Explanation

Air pressure inside the cabin is normally slightly lower than outside static pressure because of the venturi effect of air flowing past the fuselage. Using a cabin static source therefore makes the altimeter read higher, the airspeed indicator read greater, and the VSI momentarily show a climb as the lower pressure reaches it (IFH Ch. 5). Readings lower than normal or a descent indication would be the opposite of what lower static pressure produces.