“To stay airborne for more than 30 minutes after the fire was first noticed is a pretty long time” says Georg Fongern with astonishment, himself an Airbus pilot with Lufthansa and representative of the international airline pilot's association IFALPA.
After the crash of Swissair flight 111 in September 1998 which has been caused by cockpit fire, pilot procedures regarding fire and smoke in the cockpit had been fundamentally changed. “If there was a landing opportunity, which the UPS pilots had, then one doesn't care about the cause of the fire, but lands the plane as soon as possible” according to Fongern.
"It must be stressed that for smoke that continues or a fire that cannot be positively confirmed to be completely extinguished, the earliest possible descent, landing, and EVAC must be done.
If a smoke, fire or fumes situation becomes uncontrollable, the flight crew should consider an immediate landing. Immediate landing implies immediate diversion to a runway. However, in a severe situation, the flight crew should consider an overweight landing, a tailwind landing, an off-airport landing, or a ditching."
..I have copied it out of the 744 QRH section C/L intro.
this is how airplane manufacturer wants as to act in case of Smoke, Fire or Fume
the crew of UPS 6 made a possible earliest descent, indeed, but was not able to make a landing dew to smoke in the cockpit, ... I feel a respect to decisions they have made and as a pilot realizing they were on the most safe plan of action.
Only investigation will tell as of other factors affected their flight
all other speculations seems to me to be pointless and only investigation can reveal that amount of Human Factor involved not any other of the aviators in the whole world.