DME Range Accuracy RNAV

The accuracy requirements for the two types of DMEDME —Distance Measuring Equipment are exam facts. For a DME(P), the newer (precision) type of DMEDME —Distance Measuring Equipment, the requirement is simple: no more than 0.2 miles out from the correct range. For the older type of DMEDME —Distance Measuring Equipment — confusingly, called DME(N) — multiply the range you are at by 0.0125 (or take 1.25% of the range) and then add 0.25 nm. So for example, at 100 nm the accuracy for a DME(N) would be $0.0125 \times 100 = 1.25 + 0.25 = 1.5 \text{nm}$.