This is unfortunately not the case from attempting to use this feature. It works as described for every vehicle EXCEPT helicopters (and i am told by others all pilots).
whilst the command you posted DOES turn the light on, the AI pilot turns it off after 0.2 seconds.
The only current solution is to turn it on every 0.01 seconds via a sleep loop, which is not appropriate!
It does not matter what behavior your set it to, even in careless helicopters still turn off the search light (but leave the collisions on).
setting the unit, or yourself as captive makes no difference either (or both!).