Mansfield, thanks for the additional explanation.
I agree with your interpretations of the data, but it might be worth checking with Boeing for TALPA confirmation.
Re non effect of reverse; there may be an explanation on slide 31 of the Boeing presentation – ‘reverse may be additive’; or without rev, auto brake 2, and low braking action, then because the decal target cannot be achieved the distance will be longer, but with better braking action, this is not so.
Your earlier question
“how to implement the new FAA landing distance assessment requirements” is the critical aspect in the discussion.
I am ‘old school’ UK, where landing data was interpreted as requiring factors as per dispatch (equivalent safety), and that ‘safety margin’ was considered as in #16. The background docs are below.
In more recent times, the focus has changed towards ‘actual’ landing performance (FAA always has?) and the risks on contaminated runways. It appears that the requirement for landing within 60% of the runway has been reinterpreted (see #16 regulatory precedence EASA?) or alternative applications (FAA?).
Europe, specifically the UK, promotes a ‘clear runway’ policy and additional risk management for unavoidable contamination. Although the risks may be higher, less safety margin, they could be ‘acceptable’ providing the frequency of operation is minimal and the landing accuracy is improved - there is no acceptable ‘landing zone’. Both of these require operator/pilot judgement which may be eroded with time; wet/contamination landings (data) become the norm because of commercial, airspace, runway usage pressures. The EASA certification requirements are in AMC CS 25.1591, which provides ‘chilling’ operational advice – apparently without any need for operators to heed the CS 25 warnings – or even read them (~page 864).
For thought:- If FAA had required fully factored landings, then why issue SFO 06012?
Similarly for EASA; or if the full factors are a landing requirement then why does the industry need FOLD?
“… we have shifted from a large margin, average risk approach to a narrow margin, specific risk approach’.
Yes; previously some authorities implied a large landing margin, the FAA less so. Now regulators place greater responsibility for assessing and managing the risk on operators, and particular the crew.
For this they require greater knowledge and better regulatory guidance, including regulatory interpretation, which is sadly lacking or at best confusing/conflicting. E.g. certification landing performance is based on air distance with little margin, on which actual distance is based; but operational regulation only recommends a small factor yet discusses a much greater landing zone.
Thus
“how to implement the new FAA landing distance assessment requirements”; we should always add more than the minimum 15% margin, and for any wet or contaminated runway use the next lower reported braking action
SAFO 15009 and review the
Boeing tech bulletin; landing on slippery runways , MD 80 similar.
Review the policy and wording of advice and requirements on ‘landing zone’.
Refs
Old School, but may be current.
AIC 14/2006 LANDING PERFORMANCE OF LARGE TRANSPORT AEROPLANES
AIC 86/2007 RISKS AND FACTORS ASSOCIATED WITH OPERATIONS ON RUNWAYS AFFECTED BY SNOW, SLUSH OR WATER
Operations on Contaminated Runways Safety Notice 2011 016
Current EASA
Review of aeroplane performance requirements for CAT operations
CS 25 Certification Specifications and Acceptable Means of Compliance for Large Aeroplanes (~page 864)
Airbus view of TALPA 2010
and
Workshop Runway Friction and Aircraft Braking | EASA