We have had nearly 3 weeks of constant rain and yesterday blue sky. A friend and myself decided to go for a couple of hours flying. Nil wind , some clouds at 6,000 ft nothing to worry about. Temperature on ground 95deg F ,humidity was 97%. We were in a Cessna 172 [his]. we had 120 liters in tanks . Flight was going to use about 80 liters . We had to push the aircraft about 500 yards to be clear of tarmac repairs from rain . By this time we were panting and covered in sweat. I had a mouth full of water from a 500mls water bottle and he had a can of coke [cold ]. Take off normal and then the sun streaming in through the windscreen. Temperature in cockpit was 116deg F . My T shirt was soaked and my shorts were close to being saturated . The sweat was dripping off my elbows . It was like being in hot oil regardless of the vents . Humidity was at least 97% plus . It was a great flight ,testing out his new toys on his aircraft . We were about 5 miles out and I asked him how much fuel did he think we still had on board . I told him I think we have used 70 liters so how much left ?
He said 15 liters and then i could see the panic in his face . NO ,we started with 120 liters . Out came the phone and he is trying to use the calculator . I am then trying to use the check sheet before landing . I had another couple of mouthfuls of water . Then i realise , things are not right with me . I forgot to make any radio calls . I am on finals and I want to to throw up. We bounced down the runway . Parked the aircraft and raided his fridge in the hangar . He had heaps of cold water in fridge . What I learnt was dehydration creeps up on you and you must make a constant effort to drink water. we both were concentrating too much on the new toys fitted to his aircraft and not our health.
[His toys is a Garmin glass panel and a AoA gauge . It was after a while that I realised the Garmin told us all the fuel used and and remaining .