Practice Relating to Rule 7. The Principle of Distinction between Civilian Objects and Military Objectives
Section E. Attacks against civilian means of transportation
Germany’s Military Manual (1992) provides that enemy aircraft used exclusively for the transport of civilians may neither be attacked nor seized. Their protection ends
if such [aircraft] do not comply with conditions lawfully imposed upon them, if they abuse their mission or are engaged in any other activity bringing them under the definition of a military objective … Such aircraft may be requested to land on ground or water to be searched.