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The altitude indicated in the messages sent from the Explore app (Android) is wrong (approx. 50 m higher). The altitude in messages sent from inReach are correct

Alberto
over 1 year ago

As I mentioned in the Explore forum, the altitude indicated by the app is wrong. It is the Ellipsoidal altitude and not the Orthometric altitude. The difference is very important: approximately 50 meters more or less in Spain, varying according to the area of the earth.

Today I have seen that when a message is sent from that app, the transmitted altitude is wrong.

However, the altitude reported by the inReach M2 in Navigation and attached to a message sent from that device is correct.

The difference is big and can cause a rescue team to be looking for someone at a different altitude. You can check it by sending a message from the app and from inReach, in a clear place

  • 0 over 1 year ago

    In this image, the deviation between the Ellipsoidal altitude and the Orthometric (or Geodetic) altitude is much better seen. According to the area of the earth it is different. The GPS (actually GNSS) make an internal correction and show the Orthometric altitude, which is universally indicated on all maps and the reference altitude.

    The inReach device, the vast majority of GNSS and map apps (which support ellipsoid correction, which is the majority) show the correct altitude, but the Explore app and messages sent from it do not. In some areas of the earth both altitudes coincide (area between green and yellow); in others, like almost all of Europe and in Chile, there is a difference of 50 meters. In Indonesia it is much more

  • 0 over 1 year ago

    I mean that it is possible that the problem is with the mobile and not with the Explore app. I don't know, but on my mobile, the other mountain navigation apps I have (OsmAnd and Oruxmaps) have the option (activated) to show the Orthometric altitude instead of the Ellipsoidal one. In the Explore app it does not have that option and, at least on my mobile, it only shows the Ellipsoidal altitude (in all of Europe it is +50 meters, approximately).

    As the WGS84 geoid was created in the USA, there is no deviation between the ellipsoid and the geoid (green-yellow área) and therefore both altitudes coincide quite approximately. We have the problem in Europe, Indonesia and Chile (approximately). I already said that maybe it is a problem only with my mobile and that is why I ask it in the forum. I have tried on another mobile with the same result.