This first attempt aims to determine the extent of students' covert use of machine translation (MT) in the online assessment of their sight translation, the strategies of such use, and its signs. The study is based on the analysis of target texts (TT) of specialised online sight translation from Ukrainian into English by 13 BA and 10 MA students. The procedure involved the comparison of the students' TTs with their MT counterparts. Signs of covert MT were found in 46% of the BA and 30% of the MA students' translations. The main method of this covert MT use is "simultaneous post-editing", i.e., the immediate oral post-editing of the MT text generated by the students on their screens and hidden from the assessor, while they deliver their supposedly original TTs. Simultaneous post-editing strategies range from replacing individual lexemes with their synonyms, adding and deleting elements, changing the syntactic functions of words or phrases, rearranging sentence fragments, transforming their structure, to applying several of these strategies simultaneously. Other methods of concealment include alternating MT systems in translating the same source text, as well as artificially slowing down the process of reading the TT from the screen, accompanied by pauses in the relevant text fragments to perform certain mental operations. In order to increase objectivity, the author recommends a delayed assessment of students' online interpreting recordings. The research perspective is to study the didactic potential of simultaneous post-editing as a procedure for developing general interpreting skills.