Certified Flight Instructor - Flight Instructor Airplane Practice Exam

What DME indication should be expected when directly over a VORTAC site at approximately 6,000 feet AGL?

1. 0

2. 1

3. 1.3

4. 4.5

The correct answer is: 1

When an aircraft is directly over a VORTAC at approximately 6,000 feet above ground level (AGL), the Distance Measuring Equipment (DME) reading is expected to indicate a distance from the VORTAC that is proportionate to the altitude above ground level. The DME calculates the slant range distance to the VORTAC, taking into account the altitude of the aircraft. At 6,000 feet AGL, the aircraft's altitude directly contributes to the DME reading. The geometric relationship involves both vertical and horizontal distances, resulting in the DME reading reflecting a distance that may be less than the actual altitude due to the descending path towards the VORTAC. Considering that the typical DME range at 6,000 feet is about 1 nautical mile for every 1,000 feet of altitude, the expected reading of approximately 1 mile is logical. This aligns with the understanding of the DME functions, where the indicated distance typically reveals a simplified calculation based on altitude, showing 1 as the most accurate figure when factoring the slant range. This understanding helps pilots anticipate the DME readings as they approach or cross directly over a VORTAC, ensuring they can accurately navigate and maintain situational awareness.