Originally Posted by
Capn Bloggs
With respect to landing distance.....
if you float another 500m, you still have room up your sleeve (3500-1800-500). Not that I condone regularly landing 500m past the performance TDP!
Bloggs, respectfully. While you are correct with the geometry, there are couple of points missing once we shift focus from the math onto day-to-day recurring airline operations and quality assurance.
Firstly the terminology. Having calculated the exact same value of 450m independently before for my small Airbus, that is not the TDZ as the word is understood. Nominal distance-to-touchdown for sure, why not say 350-550 m is a 'valid touchdown range' where the landing performance figures are not invalidated. That is to say, the inherent margins from the calculation will cover ~100 m loss. (if the attempt was legally justified to begin with, unlike
MK1602).
TDZ is commonly understood as either
a) 900 m or 1/3 of the runway whichever comes shorter (various ALAR toolkits)
b) the first part that is painted with TDZ zone markings.
now, A) above is an utterly useless concept that is a repeated pain to unlearn on all the performance and landing safety courses we would attend, design, teach or audit.
but B) has good merit. Since there are rules (ugly exceptions such as Burbank 9 notwithstanding), if the touchdown is not happening before the markings end the pilots can read that and need to understand beyond those all of the performance margins could be long eaten up. Thus pushing or allowing one's self to complete the landing becomes a stunt, similar to flying on 4 red PAPIs. One cannot evaluate any more how bad it is and there is no protection or recognition pattern to judge if it is becoming suicidal. Not that there are many tools left once REVs get deployed anyhow-
Real men don't touch beyond the painted zone, no matter the runway length. It is a display of professionalism, resolve and upholding of standards expected from the PIC authority.
While you may have retired successfully and I still have only 15 yrs to go, there are bright colleagues starting their careers as we type. They will need to do better than both of us when 4th stripe arrives.