Impossibility through inadequacy arises where the crime itself is perfectly feasible, but the defendants adopt, or seek to adopt, a method that cannot work, e.g. 'poisoning' someone with a substance that, unknown to them his harmless, or trying to open a bombproof safe with explosives which cannot blow it open. Logic clearly shows that such an argument cannot succeed in any situation: a defendant who sets out to kill should not get off simply because they choose a method that is doomed to fail. Such a defendant will be convicted of an appropriate inchoate offence. However, this type of factual impossibility may provide a defence in extreme cases, such as where D tries to bring down a passenger jet by firing at it with a child's water pistol, because this type of act could not be regarded as ever preparation, let alone an act that has gone beyond preparation.