GPS vs. DME Distances - puzzle

[guzziguy]

I have both a IFR GPS and a DME.
Everyone knows that the DME measures SLANT range and the GPS measures point to point distance.

This means that, all things being equal, the slant range will always be greater than the GPS distance to varying degrees.

An interesting thing happened on the way to the forum the other day...

The SLANT range measured LESS THAN the GPS range.

Any thoughts on this? It's only happened once (that I noticed). Does a DME need to be calibrated???

Tks

 

[Canuck]

 

[guzziguy]

 

[kgreen]

 

[kshaw]

 

[kju1pitt]

 

[Canuck]

 

[Reece]

 

[kju1pitt]

 

[guzziguy]