So I had my first cutaway this weekend, first jump of the morning too! I am a newbie, finished my Aff up this March so I only had 13 jumps prior. Exit and freefall went very smoothly and even my deployment went well. Once under canopy I left my breaks stowed to perform rear riser turns(for the A license proficiency card), one left and one right. After I was at about 4-3.5k and unstowed my breaks, here's when it happened. My right came out fine and left line somehow got jammed and the toggle handle was flapping down by my side near my hip and I could see the cat's eye at the ring where the breakline feeds through. So I immediately went into a downward spiral. I gave two attempts to try and unjam the line and it wouldn't budge, so I looked down, got sight of my handles and pulled accordingly(got some praise for holding onto both cutaway handles). I was shocked at how fast I was under the reserve(had the RSL as well), couldn't have been more than a second or two from pulling the first handle. Definitely got the juices flowing! Flew my landing pattern and came down smoothly. Nice to know the cutaway system works so well! After, I shook it off and did 4 more great jumps to complete the day. Any thoughts on how that break line got jammed? I only had a couple adrenaline filled seconds to analyze it so I really couldn't see if there where any bunches of line that resembles a knot or anything.