I have extensive experience with VBA in Excel and I am also a military aviator with a Masters in Systems Engineering (Space Systems). I can easily create a VBA subroutine that will comb through your data and identify all of the cycles (as defined above as when the ALT becomes equal to the initial ALT value).
I will assume that you do not want to count a cycle unless the Airframe Hours (column H) has also changed - so as to eliminate any fluctuations due to the inherent errors in the altimeter system. Alternatively, this could be assured by setting a threshold of change in either absolute value of ALT change or a percentage change value.
In order to confirm my understanding of your algorithm, the provided file would have 12 separate cycles if only counting occasions where the ALT actually equals the initial value of 6534 (1: Row 3-473, 2: Row 474-649, 3: Row 650-841, 4: Row 842-996, 5: Row 997-1467, 6: Row 1468-1749, 7: Row 1750-2814, 8: Row 2815-2996, 9: Row 2997-3215, 10: Row 3216-3413, 11: Row 3414-3651, 12: Row 3652-3684). Alternatively, if the condition were less than or equal to the initial ALT value of 6534, this would produce 41 separate cycles.
Should any of what I have written require further explanation, please PM me and I would be happy to discuss.