When we are talking about certification performance landing trials we are talking about TP finesse .. which is not the sort of finesse the line pilot might aspire to day in, day out.
Probably the most alarming (if not outright frightening) experience I've had was the first time in the back on such trials. It would have been nice had the boys briefed me beforehand ... c'est la vie.
TPs are not paid to do smooth landings which the little old grey headed grandmother in row 25 will think "that was nice, dear" .. they are paid to get numbers .. good numbers.
Maximum manual braking better believe it.
"positive" touchdown been more than the odd aeroplane broken in half during such touchdowns
no reverse doesn't make a whole lot of difference on a dry runway
runway length limitation is demonstrated CD (certified distance) + 67%"
You and I will NOT achieve the TP's data unless the Gods are smiling broadly on the day and we are VERY lucky.
Not even the TP will achieve his/her own book figures every time.
In the real world, the TP does his/her best to get the shortest distances he/she can. If he/she doesn't like the particular test point result .. read "I really could have done better on that one", he/she scraps that result.
Once the TP has done his/her bit, the aerodynamicists look at the test set and throw out a few more "not quite right" results.
The end data set (considered to be "good") then is put up to the Regulator for assessment.
Unfactored book figures should be viewed as being the absolute shortest distances achievable in the best circumstances with a bit of luck thrown in for good measure... ie a brick wall limiting figure
So, now it's inflight....what to brief?
- actual or
- required ldg distance....
It follows that, on the line, generally you WON'T achieve the book figure. You might not pass that distance (read "go off the end of the runway") at breakneck speed but you can reasonably anticipate going off the end to some extent. It is important to keep in mind that the speed decay characteristic curve under heavy deceleration is quite steep .. so a small distance error translates to a potentially high speed excursion .. high energy .. high damage .. front page in the local newspapers.
If you have an inflight problem impacting on landing distance, that just has to be incorporated into your overall risk assessment when figuring out just how you intend to recover the aircraft.
The level of pilot interest ought to relate to the margin on the day ..
If you have only the one runway available and it's VERY marginal, then tough luck .. you do the best you can on the day. .. and you will be very interesting in briefing the landing (and subsequent emergency services action) on the day
As the margin increases, you can relax progressively.
If you have several runways then, as PART of your flight management risk assessment, you might prioritise the runways on the basis of length. Not suggesting that the only consideration is runway length and anticipated pad factor .. but it is an important one to consider.
The end result, looking at certification and operational rules - you don't use minimum length runways as that would be an unsuccessful career and, potentially, life, strategy.
The factors mandated vary across rule sets but are intended to provide some fat for all the "normal" things which might conspire to bring you unstuck on a particular landing. Distance/0.6 (= distance x 1.67) is the factor normally applied for heavy aeroplanes.
it's 'actual' that you now consider (in the air).
I suggest in terms of the sorts of concerns listed above.
Faa insists on adding 15% to this as a safety margin
If that's all I had on heavy metal, I'd be sweating heavily during the approach ...
I just look for the approach chart and look for the category of my aircraft
The sort of training paradigms to which I was exposed had us knowing what set of available runways were reasonably available for every flight .. preflight. Always seemed to be a sound sort of insurance gameplan to me.
If SWY is larger than the CWY, V1 is increased. If CWY is larger than the SWY, V1 is decreased
Can't say that I can bring to mind any circumstance in which stopway would be longer than clearway .. do you have any examples you can cite ?
Main idea here is that the extra TODA bestowed by the clearway allows you to unbalance the takeoff (a bit more) with a lower V1 to achieve a shorter ASDA and a longer TODR. In practice the statement is just another way of saying we like to optimise the takeoff.
Keep in mind that, just because the airport authority gives you various values for distances .. your particular aircraft will not be able to use all the distance for each measure .. one will end up being limiting for the particular calculation.