G200 flight crew experiences COCKPIT DUCT TEMP HI EICAS shortly after lift off with associated high temperatures and smoke. Crew complies with QRH procedures; declared an emergency; and returned for landing. Smoke dissipated and temperature decreased prior to landing.

Narrative

Immediately after liftoff; the red 'Cockpit Duct Temperature High' annunciator illuminated on the EICAS. We noticed the cockpit was getting hot and I saw smoke. I declared an emergency and returned via VMC right traffic 1;500 FT AGL to the departure runway per our pre-departure safety briefing. While returning for landing; Second in Command ran the appropriate Emergency checklist as published in the QRH. Temperature control was switched from Automatic to Manual; per the Emergency checklist. 15-20 seconds later; the annunciator extinguished; the cockpit began to cool off; and the small amount of smoke had dissipated. Checklist called for no further action. Second in Command then ran the Normal Short-Circuit checklist and the Landing checklist. Landing accomplished without further incident. With no further indications of an overheat or a fire; we taxied to the FBO ramp; with ARFF equipment escort. No injuries to the crew or the Part 135 passengers that were onboard. ARFF personnel examined the aircraft; took my statements; and confirmed no fire was present. Second in Command and ramp personnel escorted passenger to FBO lobby. Passenger stated the cabin had gotten very hot; and they had seen smoke as well; but it dissipated quickly before landing. I discussed the events via conference call with Operations; Maintenance; and Gulfstream representative. Aircraft written up; and per Maintenance Control left unlocked; but security taped. Passenger seemed pleased with our performance; but elected to go home and reschedule the flight for another time rather than wait for a recovery aircraft and crew. Suggest a simulator training event during recurrent to cover such an incident where time is very limited for running checklists; coordination with ATC can be difficult (although it was not in this case) and the urgency to land is great. I feel we did an excellent job with this; and our previous training helped; but we really don't get to do this type of time-compression exercise in the simulator; unless we're running ahead of the training schedule; which is rare. Supplemental information from ACN 832242: Just at liftoff; the cockpit began to get very hot. The air conditioning controls were both in 'automatic' position. Both Controllers were then placed in the full cold position. Just before 400 FT AGL the EICAS red message Cockpit Duct Temperature High message appeared. The Captain and I both felt very hot air and smelled and saw smoke in the cockpit. The Captain declared an emergency and directed me to get the QRC and follow the appropriate checklist. I accomplished it and approximately 20 seconds after going to manual on the cockpit temperature controller; the EICAS message went away. The Captain directed and I accomplished the short segment checklist. We made an uneventful landing and the passengers were safely deplaned.