Which mode of flight navigation requires the pilot to use instrumental abilities to fly the aircraft?

Of the railcars listed below, which of the following is considered to be obsolete?

a. Covered hopper car b. Cryogenic liquid tank car c. High pressure tube car d. Nonpressure tank car without an expansion dome.

When coding the phrase "acquired stenosis of right external ear canal secondary to trauma," the main term to reference in the index is _____.

A. acquired B. stenosis C. canal D. trauma