Doupovec, Miroslav,
                                
                                Vondra, Alexandr    
                
                
                
                        
                            
            Given a fibered manifold , a 2-connection on  means a section . The authors determine all first order natural operators transforming a 2-connection on  and a classical linear connection on  into a connection on . (The proof implies that there is no first order natural operator transforming 2-connections on  into connections on .) Using this result, the authors deduce several properties of characterizable connections on .