This is part of the navigation log for Joe McCarthy’s aircraft AJ-T, filled in by Flt Sgt Don MacLean during the Dams Raid. It was kindly sent to me by his son, Bill.
Joe McCarthy was due to lead the second wave of five aircraft, tasked with attacking the Sorpe Dam, and should have taken off in Lancaster ED923 which had been given his favourite call sign Q for Queenie, from Scampton at 2127. However this developed a coolant leak, and the crew hurriedly transferred to the only spare available, ED825, call sign AJ-T. This turned out to be missing its all-important compass deviation card, which meant another dash for McCarthy, off to the flight offices. AJ-T finally left the ground at 2201, as you can see from the second picture above. Note in the first picture how MacLean has crossed out ‘Q’ and written ‘T’. He has also misspelt rear gunner Dave Rodger’s name as ‘Ridgers’.
Flying as fast as he could, McCarthy made up 13 or 14 minutes by the time he reached the Sorpe at 0015, to discover that he was the only one of the second wave to reach the target. Barlow and Byers had been shot down, Rice and Munro had returned to base.
The Sorpe Dam was a different construction from the Möhne and Eder Dams, which meant that bouncing the Upkeep mine towards it would not work. So the plan was to attack it by flying very low along its length and then release the mine in the middle. This would roll down the dam’s face and explode below the waterline. AJ-T’s bomb aimer George ‘Johnnie’ Johnson has told the story many times how his colleagues were less than impressed by the fact that it took no fewer than ten dives along the dam to get the line and height right. However, at 0046 he released the mine and it exploded perfectly, but it failed to destroy the dam, although the crew saw some crumbling at the top of the wall.
Their journey back to Scampton saw a certain amount of deviation from the designated route, so in the end they simply backtracked along their outbound course. They landed rather precariously at 0323, as a flat starboard tyre called for a deft bit of piloting by McCarthy.
The whole crew survived the war, and most were regular attenders of various reunions. Below, courtesy of Alex Bateman, is a picture of Don MacLean with two other Dambusters, Tammy Simpson and Danny Walker, taken at a Bomber Command dinner in London in 1987.
Pic: Alex Bateman
Dambusters Blog 
Hi, could you tell me the significance of the AJ. What did it mean?
There is no significance. Each squadron had a two letter code, and the single letter after the dash was allocated to each individual aircraft. So all 617 Squadron aircraft were AJ-, and the individual aircraft were denoted A, B, C, etc.