Rapid innovation has been made understanding and digitizing air traffic control instructions. However, to date, little has been done to harmonize work and understand differences across the globe. DLR and NASA present a scientific paper at the 44th Digital Avionics Systems Conference in Montréal, Canada, in which they compare two ontologies – from US and Europe – for interpretation of semantics of controller and pilot radio telephony transcriptions. Overall, more than 2000 ground control transmissions are evaluated from both sides of the Atlantic. Half of the transmissions, from the US side, are transformed into semantic concepts with the European ontology. These concepts contain the information, which the ontology claims as relevant. The concepts are transformed into sequences of words, which are then transformed back to semantic concepts by the US ontology, i.e., the US implementation of what information is relevant. Comparing the US concepts generated through this process against the original US concepts defines the European loss. The process is then executed the other way around on the second half of transmissions stemming from the European side, resulting in the US loss. The European command type loss is currently 2.6% absolute, whereas the US loss is 1.2%, i.e., the extraction rate of commands decreases by these losses over the Atlantic Ocean. In addition to loss comparison, the main contribution of this work is that the generalized approach enables comparison and evaluation of different ontologies and especially different implementations of the ontologies.