Originally Posted by
nigelh
Ok .. I still see more negatives from backing up than positives so don’t ever do them myself. I get the point that if it’s in the manual you do it ..... just wonder how they came to that conclusion!!!
both procedures have positives and negatives:
The vertical procedure is more easily reproducible - vertical climb to a radalt height using a given vertical speed ensures consistency and works well for elevated pads where going backwards will invalidate a radalt reading. However, there are greater performance constraints due to zero airspeed and it is easier to lose sight of the reject area (also leading to a lower usable TDP).
The Back-up technique allows a higher TDP and brings performance benefits due to being able to acquire airspeed from the higher reject heights. However, there will be greater variability in how it is flown as it relies on a sight picture, and the rate of climb and rearwards speed need judgement rather than fixed parameters. It also introduces the risk of backing into an obstacle if not properly assessed.
I've flown and trained both, and variations on them, including a hideous home-concocted company version for the B212 which was easily mishandled and was not a bunch of fun having to sit along during base checks/OPCs (actually caused more spread skids during training than actual engine failure events!)