I took off from YBMK behind one with only the length of the runway between us,
If I am not mistaken the 400 series is a Medium wake turb above 25,000kg - unlike the 300 series and below.
If this is the case I hope that you requested a wake turb waiver from ATC as this sounds like a break down of departure wake turb. Light behind Medium you gotta have 2 mins or 5 nm
