A DME station is located 1000 feet
above MSL. An aircraft flying at FL 370 in ISA conditions which is 15 NM away
from the DME station, will have a DME reading of:
These are best answered using
Pythagoras' Theorem.
DME Range^2 = Ground Range^2 +
Height^2
Ground Range = 15 NM
Height = 37000 - 1000 (ABOVE MSL) =
36,000 (Divided by 6,080 = ~6 NM) - Accurate enough!
DME^2 = (15 x 15) + (6 x 6)
DME^2 = 225 + 36
DME^2 = 261
DME = SQRT (261)
DME = 16.15 NM