Many, many years go, when I was a young pilot, there was an incident in where I live, with Airbus A300's. Company was Karair, at that time a charter subsidiary of Finnair, they had two A300's, with highest utilisation of the type then, basically flying non-stop between Finland and the Canary Islands. About 18 hours airborne per day per aircraft, if I recall correctly. At some point, it was discovered that there was a huge chunk of ice floating in the fuel tank of one of the aircraft, as the condenced water never had time to melt, and thus had never been drained from the system between the flights. The aircraft had actually been very close to fuel starvation because of this. Of course, about 20 years have passed, lessons have been learnt, and this could not happen again, couldn't it...?