Alf I typed PI (eye) not P1. Performance in flight in boeing qrh.
The distances derived are unfactored. Or they have wasted ink typing that specific phrase. Jar 1.51 does not REQUIRE any further factoring, when using these charts to determine landing distance DURING a flight.. These are actual distances achievable. The non normal charts have different distances for different problems. The emergy effect is allowed for but they are still unfactored vis a vis LDR.
I have tried to make two points.
1 There is no requirement to factor under jar after the flight is dipatched.Factoring is a function of perf A probablity, not actual on the day.
2 Factoring of PI data is an operational option not a requirement.
To assume that operators that choose to use actual data in these circumstances are dangerous is unfair. The data doesnt support that and the achievable results on line and in the sim demonstrate that factoring is an academic safety proceedure to achieve the probabilty that perf a is based on.
If you factored the ldr for an urgent heavy 763 problem with no fuel dump you would be looking a long time for a runway long enough to land.
An average long runway in this case being 3000m would require a PI Base distance of approx 1550 meteres. So lets say the PI unfactored distance (from the PI non normal charts) was 1900 metres and its wet. LDR then becomes 1900x1.67x1.15=3648m ldr.
It starts to get silly distances very quickly. Mlud the defence rests