You have understood the the article correctly.
Unfortunately, Mary's helicopter lost the contact with its GSP during the flight. If this happens, the procedure says that the helicopter then, as soon as possible, has to make an emergency landing. It happened in the middle of the desert, but the landing went thankfully fine.
The special atmospheric conditions in the area meant that the pilot hadn't any contact with the ground. For this reason, he couldn't tell anybody about their problems and no one knew what was happening to Mary and why she didn't show up.
After the helicopter was landed it succeeded to restore the contact to the GPS, and Frederik and those who accompanied him, finally got a message about what there were happened. Then, the pilot could fly to the Gaby mine, which turned out to be only 20 km away.
It hasn't been fun, but it seems that everything went very well and undramatic. I think it has been a lot more worrying for Frederik and his companions in the time when they didn't knew anything about why they didn't show up and why they couldn't get any contact with them