Last week someone took a TTN node up into the air north of Utrecht. You can see all the nice green dots of his measurement on http://pade.nl/lora/. This is a nice experiment because when you plot the data using lines to the gateway ( http://ttnmapper.org/?pade=1 if you have a fast computer), you can see the node was received by many gateways across the country. The range of LoRa when you have line of sight is incredible. We are talking about distances up to 100km.
Using the data from airborne experiments to build a coverage map is however not a good idea. I therefore would like to recommend not adding your data to these maps when going airborne. Stick to walking, bicycle or car while mapping.
In the next few days I will implement new functionality to the TTNmapper Android app which will allow you to execute an experiment. When using this mode, the data that is uploaded to ttnmapper.org will be tagged as an experiment, not contributing to the global map. You will however have a dedicated map for your experiment.
If you have a node that contributes to http://pade.nl/lora/ it is maybe a good idea to change your device address before doing your (airborne) experiment.
Please don't make this post stop you from measuring the coverage you get with LoRa. If you are using TTNmapper to do experiments at the moment, please continue. I can always filter rogue data afterwards. 
PS: If you are the person doing the airborne experiments close to Utrecht last week, please let us know. I'd love to hear what you were using and especially how high you were flying. 100km is not easily done, so I assume quite high.