Johns7022
On several occasions, I have been witness to large, really large, planes asked to meet the data, as calculated in that thick book known as "Flight Manual, Appendix 1, Performance Data". In each of those times, said Lockhed product performed exactly as advertised. Sitting in the jump seat at a USN Base Med, giving an eval. At a hair's breadth of V1, the plane gets whacked by birds. Absolutely, no time to discuss, it is a critical field length take-off, the pilot decides to stop. Once, at rest, the plane was on the numbers and we could not see the runway end out the front. An engineer went out to clear the turn around, after letting the brakes cool, which were near fuse plug limits. I cannot remember if any let go. Another time, on ice, at a NE base, landing calcs with RCR 6 (like Canadian friction reading), poor braking, more like poor to nil. Runway length 7000', LGW about 550K, getting evaluated. Calculated landing distance was 5000+ feet, we stopped abeam the 2,000 remaining boards, after standing, and I mean STANDING on the brakes and reversers.
My point in all this, is that the certification numbers are real, they are NOT to cast aside any "margins" or "pads" are not yours to play with. If you are on a field length limited take-off, options are scarce and the ideas being floated here are NOT appropriate for young, inexperienced aviators. I have attended the funerals of the similarly influenced, if not exact copies. Not happily, I assure you.
GF