While GPS has reduced the use of dead reckoning for aerial navigation , and handheld calculators have taken over many of its functions , the E6B remains widely used as a primary or backup device and the majority of flight schools demand that their students have some degree of its mastery . While GPS has reduced the use of dead reckoning for aerial navigation , and handheld calculators have taken over many of its functions , the E6B remains widely used as a primary or backup device and the majority of flight schools demand that their students have some degree of proficiency in its use .