To all,
I thought I would add a couple of points which I have not seen in the preceding discussion (forgive me if I have overlooked them).
The point has been established that the factoring of the actual landing distance is a dispatch requirement, i.e., a 6000 foot actual landing distance requires a 10000 foot runway under dry conditions. Further we have established that under wet conditions, an additional fifteen percent mist be added, thus requiring 11500 feet.
We have discussed whether this remains a requirement after dispatch. The conventional wisdom is no, it is not a requirement following dispatch. It is a planning requirement only.
In the US, a lesser known requirement resides in Operations Specification C054. This addresses the lower-than-standard minimums case (standard meaning RVR 4000 or 3/4 mile). The relevant text is:
(2) A pilot-in-command of a turbojet airplane shall not begin an instrument approach procedure when the visibility conditions are reported to be less than ¾ statute mile or RVR 4000, unless the following
conditions exist:
(a) Fifteen percent additional runway length is available over the landing field length specified for the destination airport by the appropriate Sections of the CFR.
Note that this is an operational, inflight requirement. The PIC
shall not begin an instrument approach, etc. It turns out that the "appropriate" section of the CFR is 121.195(b), making this requirement identical to that in 121.195(d), which is the 115% requirement. So the requirement is the same, but the threshold criteria and the point in the flight where it is invoked are different.
This would seem to suggest that there is an argument to made supporting the use of the dispatch landing distance requirements while in flight.
I was curious to see whether the JARs contained a similar requirement. Perusing through JAR-OPS Part 1, I could not see any such requirement...which, given my lack of familiarity with JAR, isn't saying much. However, I did note the following requirements regarding landing distance in JAR-OPS 1, Subpart G, Paragraph 1.515:
(d) If an operator is unable to comply with subparagraph
(c)(1) above for a destination aerodrome
having a single runway where a landing depends
upon a specified wind component, an aeroplane may
be despatched if 2 alternate aerodromes are
designated which permit full compliance with subparagraphs
(a), (b) and (c). Before commencing an
approach to land at the destination aerodrome the
commander must satisfy himself that a landing can
be made in full compliance with JAR–OPS 1.510
and sub-paragraphs (a) and (b) above.
Again the language requires the PIC to make an assessment, before commencing the approach, that the dispatch requirement can be met.
These seem to be two instances which are not consistent with the interpretation that the dispatch requirement goes away after takeoff. Neither directly apply to Haroon's initial scenario, but these things have a way of laying the foundation for the arguments during the hearing. All of which leads us back to John Tullamarine's point that you really need to justify non-compliance with the landing weight by declaring an emergency. Thus, you need justification beyond commercial purposes.
That said, I'll add my two cents regarding the real thing. Based on my very nearly disastrous experience with an overweight 767-300 returning to the departure field, I can state that non-precision approaches at night are probably not the best time to abandon the factoring criteria. Although we had the factored distance for our weight, the maneuvering required after breaking out at five hundred feet and 170 knot Vref put us well past the touchdown zone at an radio altitude of zero (based on the DFDR later reviewed). This necessitated a go-around, which was followed by an immediate failure of the flight directors, which was then followed by a 2000 foot ATC-instructed level off, which directly led to a flap overspeed. Having gotten that sorted out, the ensuing landing, in the touchdown zone this time, led to three of eight main tires failing.
All three of us (I was the non-flying FO) made a remarkably complimentary series of errors that night, which very nearly used up all of the margin that we had. Overweight landings need not be disasters...I've made others that were far less dramatic...but they open the door up to margin-absorbing non-routine irregularities. Although you can and should plan thoroughly and comprehensively, you retain the margins whenever possible because you will never, ever, see the one coming that gets you.