Norma relacionada
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 10. Civilian Objects’ Loss of Protection from Attack
Section B. Situations of doubt as to the character of an object
The UK LOAC Manual (2004) states: “In cases of doubt, objects are to be considered as civilian.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 5.24.3.
In its chapter on air operations, the manual states: “In case of doubt whether a vessel or aircraft exempt from attack is being used to make an effective contribution to military action, it shall be presumed not to be so used.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 12.33.