A B777 Captain reported that the use of UQ108 in Colombia is inconsistent with the aircraft's emergency descent procedure over high terrain in that there is a mountain peak; El Cucoy; that rises to an altitude some 871 FT higher than the procedure's temporary level off altitude of 17;000 FT.

Narrative

I am concerned about the use of UQ108 due to high terrain between waypoints ILVIR and GEKAR. There is a mountain peak (El Cocuy) in Colombia that is 5;428 meters or 17;841 FT high within 2 NM of the airway centerline (N0627.5 W07222.1). The B777 has an emergency descent profile for decompression that reads; 'When descending in vicinity of high terrain - level off at 17;000 FT for 10 minutes from the time the passenger oxygen was deployed.' My fear is that in the middle of the night under duress of a rapid decompression event; a crew would follow the emergency descent procedure and end up almost 1;000 FT below the terrain while on the airway. When I have been routed on UQ108 airway in the past I have discussed the issue with Dispatch; the B777 Fleet Manager and NavData/Terrain. All of these entities have told me they would look into the issue and get back to me. I am still waiting.There are other viable alternate airways in Colombia to use such as UL417 located 40 NM west which does not pose as high a risk for terrain as UQ108. I am hoping that Dispatch will block the use of UQ108 between ILVIR and GEKAR.