An aircraft receives a response from a DME station, 1236 microseconds after transmitting the interrogation. What is the slant range to the station?
- 104 nautical miles
- 100 nautical miles
- 96 nautical miles
Explanation
DME measures the round-trip time of the interrogation/reply pulse pair, then subtracts the fixed 50 microsecond ground transponder reply delay before converting to distance. Radio energy covers about one nautical mile of slant range in 12.36 microseconds round trip, so (1236 - 50) divided by 12.36 gives roughly 96 NM. The figure is slant range, not ground range, because it follows the direct line to the station.
huly asking:
My math says 100NM. Am I wrong?
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