obstacle clearance en-route
 

hi there.

for planning obstacle clearance en-route, do you consider:
use of anti-ice, engine failure, or both.

thanks

If I am not mistaken, "drift down" at the most critical point does figure into the picture for enroute situations. Can't remember if anti-ice figures into that.

Engine failure MUST be considered,

Anti-Ice use MUST be considered IF icing conditions exist,

Both of these pale into insignificance (usually) when depressurisation on passenger carrying aircraft is considered for flight over high terrain. The Net ceiling for most RPT Jet aircraft with engine inop and Anti-Ice ON is usually well above altitudes tolerable after depressurisation. Freighters may have a different point of view.