Date: 201206
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Dash 8-100
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
ATC / advisory: Ground ZZZ
Aircraft component: Air Conditioning Distribution System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Commercial
Human factors: Confusion; Physiological - Other
Anomaly: Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Person Flight Crew
When detected: In-flight
Result: General Physical Injury / Incapacitation; General Work Refused
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: The Captain and I were both sweating profusely and very hot after swapping aircraft for our last leg in a short period of time and in excessive heat. Our new aircraft was extremely hot in the cockpit--as many of our older 100 model airplanes are. The crew that had the airplane previously did not write the airplane up as being too hot for service; so we had no choice but to accept the airplane for our final flight of the day.During our pre-departure duties we were both very hot; but assumed the aircraft would cool after we took off. After we completed all of our checklists and paperwork; we pushed from the gate and departed. Unfortunately; the temperature in the cockpit never cooled off. The Captain and I were discussing how hot the cockpit was and were trying everything we could to cool it off. The Captain put the pressurization system into 'Cab Set' and raised the cabin altitude in an effort to bring in some cooler air. This did not do anything to cool off the cockpit. I put the pack temperature control in manual and selected cold several times; but the duct temp never dropped. It registered approximately 17C the entire time. About halfway through the flight I pulled out my union issued thermometer to check the ambient air temperature of the cockpit. The temperature registered 103F and cooled to about 97F for a short time. The temperature of the air from the recirculation duct registered 97F. Shortly thereafter; the Captain told me to take a break and relax; and that he would assume PM duties for me so that I could just relax for a minute and try to cool off because I was feeling very overheated. By this time; we were just starting our descent from our cruise altitude. In fact; the Captain had gotten permission from ATC to delay starting down as long as possible in hopes that we would be able to get some relief from the lower outside air temperature at our cruise altitude. Shortly before we started down; I began feeling light-headed and a bit nauseous. I was not unable to perform my duties; but I would say that I felt effects very similar to those associated with fatigue. The Captain told me that I was not looking very good and that I was pale. By this time I had stopped sweating even though I was still very hot. Eventually; I began to feel very dizzy; very nauseous; and even confused. By the time we were on the approach I was experiencing difficulty in performing simple tasks such as the before landing flows and checklists. I constantly felt that I was missing something; and I had to re-read the checklist several times to be sure that I did everything that I was supposed to do. I honestly felt a bit disoriented. It took me a while to realize that I didn't even have the correct airport charts out for the approach. Although the Captain had briefed the approach and I had paid attention; I did not catch that I had initially opened up my manual to the charts for another New York airport in error. I realized somewhere around our downwind leg that I had the wrong charts out. Prolonged exposure to the near 100 degree temperature in the cockpit was affecting me physically and degrading my physical and mental performance to the point that I was feeling very concerned. On the approach I noticed that my Captain did not look very healthy either. He had stopped sweating and had turned pale as well. We discussed our situation; and the Captain asked ATC if there were medical personnel available at the airfield. The Tower Controller told him that there was and the Captain requested that medical personnel meet our flight and evaluate us as we felt we were experiencing signs of heat illness. Neither the Captain nor I had ever experienced any of this before; so we wanted to make sure that we were safe to just go to the overnight hotel as long as we got into a cooler environment and got proper rest. After paramedics met with us; they suggested that we go to the hospital for further assistance; but did not insist. They told us that because we had started to sweat again and the color returned to our faces in the cool air-conditioned terminal we were showing rapid signs of improvement. They told us that if our symptoms returned; however; to call them immediately for transport to the hospital for further treatment. They explained that heat illness is cumulative and does not necessarily go away once you get into a cooler environment. After getting to the hotel; I ate dinner and drank plenty of water. I went to bed very early and slept through the night without further incident. The Captain ended up going to the hospital later that evening as he started to feel ill again. The next day as soon as it warmed up outside; I felt my symptoms return and went home sick along with my Captain. I feel like we have gotten so used to our aircraft being hot that it has become very difficult for pilots to draw the line at how hot is too hot. In this particular case; we were in a difficult position because the crew that had the airplane prior to us had not written it up as being too hot. Because we had not flown the airplane yet; we knew that the company would question us if we wrote it up before we had even flown it; going simply on our assumption that it probably WOULD BE hot. So really; our only options were to divert in-flight once we realized it was too hot; or continue to our destination as planned in the miserable conditions. I think that if I ever encounter this situation in the future I will react differently; regardless of what the company might think. My Captain and I saw first-hand how detrimental prolonged exposure to heat can be. I know that our airplanes are old; but more needs to be done to cool these planes down. I have heard that since Maintenance has been re-working some of the known hot 100 model airplanes complaints of hot cockpits are now on the rise; replacing reports of hot cabins. Our options seem to be either a hot cabin where the passengers are at risk for heat illness OR a hot cockpit where the crew is at risk for heat illness. This is a serious problem that needs to be addressed.




Synopsis: A Dash 8 flight crew succumbed to heat illness when they were unable to cool the cockpit and was ultimately unfit to fly the next day's flight when symptoms returned even following a layover.