A LR25 CREW EXPERIENCED HYPOXIA AT FL300 AFTER FAILING TO OPEN THE ENG BLEED VALVES BEFORE TKOF; NOT IDENTIFYING THE CABIN ALT WARNING HORN; AND NOT DONNING OXYGEN MASKS.

Narrative

DURING THE BEFORE TKOF CHKLIST; I OMITTED TURNING THE AIR BLEED SWITCH ON IN AN EFFORT TO COOL THE COCKPIT. WE DID NOT HAVE AN OPERABLE FAN IN THE COCKPIT. ON THE AFTER TKOF CHKLIST THE SWITCH WAS SOMEHOW OVERLOOKED BY BOTH CREW MEMBERS. AURAL WARNING MISIDENTED AS OVERSPEED WARNING. I DO NOT REMEMBER HEARING THE HORN BELOW 18000 FT. THE LAST FLT WE HAD IN THIS SAME ACFT A FEW DAYS BEFORE DID HAVE A FALSE AURAL TRIM IN MOTION WARNING. MY INITIAL THOUGHT WAS THAT WE AGAIN HAD A FALSE ALARM. FINALLY THE SIC DISCOVERED THE PROB AND TURNED ON THE AIR BLEED SWITCH. I DO NOT REMEMBER FLYING ABOVE 18000 FT; HOWEVER WE DID CLB TO APPROX 30000 FT BEFORE PROB IDENTED. AS I WAS HAVING DIFFICULTY CTLING THE ACFT; I DECLARED AN EMER AND WE WERE ASSIGNED A LOWER ALT. DURING THIS PROCESS WE HAD DIFFICULTY CTLING THE CABIN ALT IN EITHER AUTO OR MANUAL MODE WITH CHERRY PICKER. MY FIRST LOOK AT THE CABIN ALT SHOWN THE CABIN AT 10000 FT. THAT CANNOT BE TRUE AS ALL MASKS HAD DEPLOYED. MY NEXT RECOLLECTION IS FLYING AT 8000 FT AND HAVING A HEIGHTENED SENSE OF AWARENESS. I WAS UNABLE TO PERCEIVE THE SYMPTOMS OF HYPOXIA AT ANY TIME DURING THE FLT. MY LACK OF ACTION IN DONNING THE OXYGEN MASK COULD HAVE EASILY RESULTED IN CATASTROPHE. SOME OF THE CONTRIBUTING FACTORS WERE AN XA00 AM WAKE UP IN ZZZ1. HIGH HEAT AND HUMIDITY IN ZZZ AND ZZZ2.