Landing Performance on a sloping Runway
cos, et al, the dispatch requirements provide a margin in dry and perhaps a lesser extent in wet conditions, but it is important to understand what these involve – EU OPS 1.515 / 520. Note the assumptions, including slope, which is one reason why a prelanding check (calculation) is required (1.400).
The dispatch calculation for wet/contaminated, and contaminated runways do not have the same margins as above; they may be significantly less, thus the required level of safety has to be balanced by infrequent use and/or additional training/procedure CS 25 AMC 1591 para 8.8.1:-
“Operation on runways contaminated with water, slush, snow, ice or other contaminants implies uncertainties with regard to runway friction and contaminant drag and therefore to the achievable performance and control of the aeroplane during take-off, since the actual conditions may not completely match the assumptions on which the performance information is based. Where possible, every effort should be made to ensure that the runway surface is cleared of any significant contamination.”
i.e. clear the runway or avoid contamination wherever possible.
Actual landing distances are ‘tight’; I agree, also that many of the actual landing distances published even with +15% are unrealistic and may not provide sufficient safety margin for a range of conditions including THC / runway slope
TCH is referred to in 1.410, but does not give any values – only safety. Thus the issue is to assess the many parameters (as in this thread) to define what is acceptably safe – something which the crew has to judge at the time, but hopefully with published operational advice / guidance.
Re the OP (and some discussions), 50ft is the reference for establishing certificated performance, but it's not 'a limit' in operation, EU OPS provides guidance how this is to be applied, thus on an upsloping runway the landing should consider factors which will maintain the required level of safety, e.g. a maximum for the higher TCH, more restrictive TCH airspeed, wind limits – particularly tailwind, a limit of acceptable touchdown zone adjusted for runway condition, braking to be used, and for the operator the condition of the overrun area.
The OP ‘Captains’ view could have been expressed as an issue for learning/discussion, but if it was “I am right your are wrong”, then it would be better to jointly explore the details of landing performance, particularly the assumptions and judgements required by the lack of hard numbers which we all like to rely on.
The dispatch calculation for wet/contaminated, and contaminated runways do not have the same margins as above; they may be significantly less, thus the required level of safety has to be balanced by infrequent use and/or additional training/procedure CS 25 AMC 1591 para 8.8.1:-
“Operation on runways contaminated with water, slush, snow, ice or other contaminants implies uncertainties with regard to runway friction and contaminant drag and therefore to the achievable performance and control of the aeroplane during take-off, since the actual conditions may not completely match the assumptions on which the performance information is based. Where possible, every effort should be made to ensure that the runway surface is cleared of any significant contamination.”
i.e. clear the runway or avoid contamination wherever possible.
Actual landing distances are ‘tight’; I agree, also that many of the actual landing distances published even with +15% are unrealistic and may not provide sufficient safety margin for a range of conditions including THC / runway slope
TCH is referred to in 1.410, but does not give any values – only safety. Thus the issue is to assess the many parameters (as in this thread) to define what is acceptably safe – something which the crew has to judge at the time, but hopefully with published operational advice / guidance.
Re the OP (and some discussions), 50ft is the reference for establishing certificated performance, but it's not 'a limit' in operation, EU OPS provides guidance how this is to be applied, thus on an upsloping runway the landing should consider factors which will maintain the required level of safety, e.g. a maximum for the higher TCH, more restrictive TCH airspeed, wind limits – particularly tailwind, a limit of acceptable touchdown zone adjusted for runway condition, braking to be used, and for the operator the condition of the overrun area.
The OP ‘Captains’ view could have been expressed as an issue for learning/discussion, but if it was “I am right your are wrong”, then it would be better to jointly explore the details of landing performance, particularly the assumptions and judgements required by the lack of hard numbers which we all like to rely on.
