Landing Distances - EASA CAT.POL.A.230
Thread Starter
Landing Distances - EASA CAT.POL.A.230
I've read all the previous threads on PPRuNe and elsewhere regarding landing distance performance and Performance A factors; yet even the most in depth thread I found on this site is still very subjective as to whether CAT.POL.A.230 f) applies when carrying out an inflight, pre-landing assessment of the destination airfield with the latest weather.
For this question I am referring to commercial operations on a Performance A aircraft. The situation I am referring to is pre-landing performance assessment of the planned destination, under normal circumstances, using the actual conditions. Abnormal, Emergency, or other "RE-planning" diversions are not considered.
Here's the section from IR-OPS Annex IV:
As I have understood all the threads I've found on this subject, some believe the requirements of a) - d) do not need to be applied once enroute to your planned destination and only the relevant AFM landing performance is applicable. I interpret the above regulation to mean that we are required to ensure our landing performance calculation complies with these Performance A factors. I could be entirely wrong.
Our AFM landing performance figures, and our performance calculations created via our briefing software, allow me to calculate operational dispatch planning via a supplement and then AFM landing performance, which is factored as per CAT.POL.A.230 a) 1) and CAT.POL.A.235 a). For my aircraft, the operational dispatch planning figure seem reasonable and the AFM Supplement it is derived from does state it complies with the EASA requirements to land within 60% of the LDA and we can further factor the landing distances for wet runways. (i.e. it complies with CAT.POL.A.230 a) 1) and CAT.POL.A.235 a)) The supplement specifically states that it is a requirement to calculate the landing performance prior to approach, and to use the main AFM landing performance section and the prevailing weather at the destination airfield to calculate this actual landing performance. Using the applicable Performance A factors with the main AFM landing performance figures results in severely restricted landing performance, in particular for wet runways.
The aircraft manufacturer has been very helpful responding to my enquiries seeking clarification. They have advised that the requirement to factor the landing distance to land with 60% of the LDA is not applicable once enroute. (They don't mention CAT.POL.A.230 a) 1) specifically.) In practice, we currently apply these factors via the FMS and crosscheck the FMS performance against our briefing performance with CAT.POL.A.230 a) 1) factor (x1.67), or the CAT.POL.A.235 a) factor (x1.92), applied.
Operational Dispatch Planning does state compliance with these two factors. AFM landing performance section does not state any factor, although clearly one is already applied otherwise there would not be such a large reduction in landing performance when comparing the operational dispatch planning to the AFM landing performance with either the 1.67 or 1.92 factors applied. AFM landing performance without these factors applies is significantly less restrictive than operational dispatch planning figures. It is not stated by what factor the landing performance calculated directly from the AFM is factored by. I presume it has some factor to avoid the risk of runway overrun excursions. Assuming CAT.POL.A.230 a) 1) is applicable, we are therefore unable to show the standard AFM landing performance complies with this.
I know this subject is raised a few times a year, but I haven't seen a decisive consensus in any of the threads I've read regarding the application of CAT.POL.A.230 a) 1) and CAT.POL.A.235 a) during inflight assessment of the planned landing. I intended to set this up as a simple "they apply" or "they don't apply" poll but haven't figured out how to do it here on PPRuNe. I've been pouring over IR-OPS, AFM Sections, AFM Supplements and back and forth with the manufacturer and I'm afraid I'm struggling to see the wood for the trees… Your collective advice is much appreciated!
For this question I am referring to commercial operations on a Performance A aircraft. The situation I am referring to is pre-landing performance assessment of the planned destination, under normal circumstances, using the actual conditions. Abnormal, Emergency, or other "RE-planning" diversions are not considered.
Here's the section from IR-OPS Annex IV:
CAT.POL.A.230 Landing — dry runways
a) The landing mass of the aeroplane determined in accordance with CAT.POL.A.105(a) for the estimated time of landing at the destination aerodrome and at any alternate aerodrome shall allow a full stop landing from 50 ft above the threshold:
1) for turbo-jet powered aeroplanes, within 60 % of the landing distance available (LDA); and
2) for turbo-propeller powered aeroplanes, within 70 % of the LDA.
b) For steep approach operations, the operator shall use the landing distance data factored in accordance with (a), based on a screen height of less than 60 ft, but not less than 35 ft, and shall comply with CAT.POL.A.245.
c) For short landing operations, the operator shall use the landing distance data factored in accordance with (a) and shall comply with CAT.POL.A.250.
d) When determining the landing mass, the operator shall take the following into account:
1) the altitude at the aerodrome;
2) not more than 50% of the headwind component or not less than 150 % of the tailwind component; and
3) the runway slope in the direction of landing if greater than ± 2 %.
e) For dispatching the aeroplane it shall be assumed that:
1) the aeroplane will land on the most favourable runway, in still air; and
2) the aeroplane will land on the runway most likely to be assigned, considering the probable wind speed and direction, the ground handling characteristics of the aeroplane and other conditions such as landing aids and terrain.
f) If the operator is unable to comply with (e)(1) for a destination aerodrome having a single runway where a landing depends upon a specified wind component, the aeroplane may be dispatched if two alternate aerodromes are designated that permit full compliance with (a) to (e). Before commencing an approach to land at the destination aerodrome, the commander shall check that a landing can be made in full compliance with (a) to (d) and CAT.POL.A.225.
g) If the operator is unable to comply with (e)(2) for the destination aerodrome, the aeroplane shall be only dispatched if an alternate aerodrome is designated that allows full compliance with (a) to (e).
CAT.POL.A.235 Landing — wet and contaminated runways
a) When the appropriate weather reports and/or forecasts indicate that the runway at the estimated time of arrival may be wet, the LDA shall be at least 115 % of the required landing distance, determined in accordance with CAT.POL.A.230.
a) The landing mass of the aeroplane determined in accordance with CAT.POL.A.105(a) for the estimated time of landing at the destination aerodrome and at any alternate aerodrome shall allow a full stop landing from 50 ft above the threshold:
1) for turbo-jet powered aeroplanes, within 60 % of the landing distance available (LDA); and
2) for turbo-propeller powered aeroplanes, within 70 % of the LDA.
b) For steep approach operations, the operator shall use the landing distance data factored in accordance with (a), based on a screen height of less than 60 ft, but not less than 35 ft, and shall comply with CAT.POL.A.245.
c) For short landing operations, the operator shall use the landing distance data factored in accordance with (a) and shall comply with CAT.POL.A.250.
d) When determining the landing mass, the operator shall take the following into account:
1) the altitude at the aerodrome;
2) not more than 50% of the headwind component or not less than 150 % of the tailwind component; and
3) the runway slope in the direction of landing if greater than ± 2 %.
e) For dispatching the aeroplane it shall be assumed that:
1) the aeroplane will land on the most favourable runway, in still air; and
2) the aeroplane will land on the runway most likely to be assigned, considering the probable wind speed and direction, the ground handling characteristics of the aeroplane and other conditions such as landing aids and terrain.
f) If the operator is unable to comply with (e)(1) for a destination aerodrome having a single runway where a landing depends upon a specified wind component, the aeroplane may be dispatched if two alternate aerodromes are designated that permit full compliance with (a) to (e). Before commencing an approach to land at the destination aerodrome, the commander shall check that a landing can be made in full compliance with (a) to (d) and CAT.POL.A.225.
g) If the operator is unable to comply with (e)(2) for the destination aerodrome, the aeroplane shall be only dispatched if an alternate aerodrome is designated that allows full compliance with (a) to (e).
CAT.POL.A.235 Landing — wet and contaminated runways
a) When the appropriate weather reports and/or forecasts indicate that the runway at the estimated time of arrival may be wet, the LDA shall be at least 115 % of the required landing distance, determined in accordance with CAT.POL.A.230.
Our AFM landing performance figures, and our performance calculations created via our briefing software, allow me to calculate operational dispatch planning via a supplement and then AFM landing performance, which is factored as per CAT.POL.A.230 a) 1) and CAT.POL.A.235 a). For my aircraft, the operational dispatch planning figure seem reasonable and the AFM Supplement it is derived from does state it complies with the EASA requirements to land within 60% of the LDA and we can further factor the landing distances for wet runways. (i.e. it complies with CAT.POL.A.230 a) 1) and CAT.POL.A.235 a)) The supplement specifically states that it is a requirement to calculate the landing performance prior to approach, and to use the main AFM landing performance section and the prevailing weather at the destination airfield to calculate this actual landing performance. Using the applicable Performance A factors with the main AFM landing performance figures results in severely restricted landing performance, in particular for wet runways.
The aircraft manufacturer has been very helpful responding to my enquiries seeking clarification. They have advised that the requirement to factor the landing distance to land with 60% of the LDA is not applicable once enroute. (They don't mention CAT.POL.A.230 a) 1) specifically.) In practice, we currently apply these factors via the FMS and crosscheck the FMS performance against our briefing performance with CAT.POL.A.230 a) 1) factor (x1.67), or the CAT.POL.A.235 a) factor (x1.92), applied.
Operational Dispatch Planning does state compliance with these two factors. AFM landing performance section does not state any factor, although clearly one is already applied otherwise there would not be such a large reduction in landing performance when comparing the operational dispatch planning to the AFM landing performance with either the 1.67 or 1.92 factors applied. AFM landing performance without these factors applies is significantly less restrictive than operational dispatch planning figures. It is not stated by what factor the landing performance calculated directly from the AFM is factored by. I presume it has some factor to avoid the risk of runway overrun excursions. Assuming CAT.POL.A.230 a) 1) is applicable, we are therefore unable to show the standard AFM landing performance complies with this.
I know this subject is raised a few times a year, but I haven't seen a decisive consensus in any of the threads I've read regarding the application of CAT.POL.A.230 a) 1) and CAT.POL.A.235 a) during inflight assessment of the planned landing. I intended to set this up as a simple "they apply" or "they don't apply" poll but haven't figured out how to do it here on PPRuNe. I've been pouring over IR-OPS, AFM Sections, AFM Supplements and back and forth with the manufacturer and I'm afraid I'm struggling to see the wood for the trees… Your collective advice is much appreciated!
Last edited by Journey Man; 21st Dec 2014 at 08:05. Reason: A - D instead of A - E
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The first sentence refers you to CAT.POL.105, which says that all these requirements apply at the start of the takeoff run. Therefore once you are airborne only the actual landing distances need to be considered.
As with all these things, what is legal may not be sensible!
As with all these things, what is legal may not be sensible!
Thread Starter
Whilst I agree that CAT.POL.A.105 a) 1) does state "at the start of the take-off; or" I'm unconvinced that this caveat is an exemption from further performance restrictions as CAT.POL.A.105 a) 1) is a general regulation and it could equally be argued that CAT.POL.A.100 a) is applicable as it states, "The aeroplane shall be operated in accordance with the applicable performance class requirements." One of which is CAT.POL.A.230 f) stating "Before commencing an approach to land at the destination aerodrome, the commander shall check that a landing can be made in full compliance with (a) to (d) and CAT.POL.A.225."
The part that does interest me from CAT.POL.A.105 is
So maybe this does support what you're saying i.e. that the regulations are mindful of double application of factors and hence the AFM is sufficient.
So far:
No factor: 1
Factor: 0
The part that does interest me from CAT.POL.A.105 is
CAT.POL.A.105 b)
(b) The approved performance data contained in the AFM shall be used to determine compliance with the requirements of the appropriate chapter, supplemented as necessary with other data as prescribed in the relevant chapter. The operator shall specify other data in the operations manual. When applying the factors prescribed in the appropriate chapter, account may be taken of any operational factors already incorporated in the AFM performance data to avoid double application of factors.
(b) The approved performance data contained in the AFM shall be used to determine compliance with the requirements of the appropriate chapter, supplemented as necessary with other data as prescribed in the relevant chapter. The operator shall specify other data in the operations manual. When applying the factors prescribed in the appropriate chapter, account may be taken of any operational factors already incorporated in the AFM performance data to avoid double application of factors.
So far:
No factor: 1
Factor: 0
Only half a speed-brake
Hi,
The way I read it:
If you cannot meet the requirements of (e1), you may still dispatch with two alternates and then, before comitting to original destination, the dispatch conditions needs to be satisfied even when airborne.
It seems to make a lot of sense. If you cannot meet the dispatch criteria before flight, you are still allowed to depart, provided the dispatch criteria will be satisfied before commencing the approach.
The way I read it:
If you cannot meet the requirements of (e1), you may still dispatch with two alternates and then, before comitting to original destination, the dispatch conditions needs to be satisfied even when airborne.
It seems to make a lot of sense. If you cannot meet the dispatch criteria before flight, you are still allowed to depart, provided the dispatch criteria will be satisfied before commencing the approach.
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Simply put:
BEFORE departure, despatch landing performance (planning performance) is to be taken into account, to ensure the flight can be completed to its destination, OR if unable two alternates (eg a new destination plus diversion to an alternate) must be valid before dispatch with associated fuel requirements.
AFTER departure, enroute landing performance (inflight actual performance data) is taken into account, to ensure the flight can be landed at intended destination.
Intended destination in the latter paragraph may well be the original destination if actual conditions are better than forecast conditions which prohibited its planning use to be suitable.
For instance:
Due WIP in GDN a reduced runway length exists and forecast weather conditions are SN with runway state reported at planning stage to be braking action medium.
The above reduces you planned maximum landing weight to conditions which prevail and the safety margins built in to them, thus well reducing your payload capability.
Operational experience has shown the runway will most likely be treated by the time you arrive, but no guarantees, thus you cannot assume this and dispatch performance is thus defining a payload reduction.
Your flight will now need to be using a second alternate with no restrictions for planning performance calculations, so all payload booked can be taken.
Once departed and approaching destination, the crew can access actual conditions in GDN and establish if Inflight Performance is suitable to make an approach at the scheduled destination, win for all parties involved, passengers at destination, aircraft in place for return trip, no diversion requirement.
BEFORE departure, despatch landing performance (planning performance) is to be taken into account, to ensure the flight can be completed to its destination, OR if unable two alternates (eg a new destination plus diversion to an alternate) must be valid before dispatch with associated fuel requirements.
AFTER departure, enroute landing performance (inflight actual performance data) is taken into account, to ensure the flight can be landed at intended destination.
Intended destination in the latter paragraph may well be the original destination if actual conditions are better than forecast conditions which prohibited its planning use to be suitable.
For instance:
Due WIP in GDN a reduced runway length exists and forecast weather conditions are SN with runway state reported at planning stage to be braking action medium.
The above reduces you planned maximum landing weight to conditions which prevail and the safety margins built in to them, thus well reducing your payload capability.
Operational experience has shown the runway will most likely be treated by the time you arrive, but no guarantees, thus you cannot assume this and dispatch performance is thus defining a payload reduction.
Your flight will now need to be using a second alternate with no restrictions for planning performance calculations, so all payload booked can be taken.
Once departed and approaching destination, the crew can access actual conditions in GDN and establish if Inflight Performance is suitable to make an approach at the scheduled destination, win for all parties involved, passengers at destination, aircraft in place for return trip, no diversion requirement.
Thread Starter
FlightDetent, I agree with the requirement for two alternates in the case of (e) (1). If the requirements for (e) (1) were met before departure, what's your interpretation on the 60% requirement?
Just to throw in an argument against the use of CAT.POL.A.105 (a)(1) to act as a caveat to exempt the airborne, enroute situation… CAT.POL.A.105 (a) (1) is a General Requirement, and there is CAT.POL.A.100 which states
So I understand this to mean that CAT.POL.A.105 is secondary to the Performance Class Requirements stated in CAT.POL.A.230 (f). I've sought clarification from the regulator regarding this query and am awaiting their response.
Just to throw in an argument against the use of CAT.POL.A.105 (a)(1) to act as a caveat to exempt the airborne, enroute situation… CAT.POL.A.105 (a) (1) is a General Requirement, and there is CAT.POL.A.100 which states
CAT.POL.A.100
(a) The aeroplane shall be operated in accordance with the applicable performance class requirements.
(a) The aeroplane shall be operated in accordance with the applicable performance class requirements.
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Journey Man, dispatch performance has the 60% safety built in, which is a planning factor. Do not confuse inflight/en-route planning with dispatch planning requirements.
Once dispatched, the planning has been completed preflight, thus does not apply further, and inflight performance takes over which is more detailed and generally more forgiving, with its own factors applied, thus the 60% need not be applied any more.
Once dispatched, the planning has been completed preflight, thus does not apply further, and inflight performance takes over which is more detailed and generally more forgiving, with its own factors applied, thus the 60% need not be applied any more.
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I spoke about this matter with many colleagues, and still was not able to find an agreed solution.
Our flight operation manager tends to apply the more restrictive interpretation, using the planning minima even after lift off, at least when it comes to destination airports.
Let's make an example, which actually occurred to me recently.
Destination was Cannes, and in order to comply with the planning minima a headwind of at least 10 knots was required in order to land rwy 17.
The wind required was present in the forecast, and two alternates were selected. All the dispatch requirements were met.
During the descent to destination we checked the wind, which had decreased, falling below the minimum component necessary for us in the planning phase.
What were we supposed to do? It is actual phase now, and WITHOUT the 60% factorization we are able to take any runway, but WITH the factorization we shouldn't be landing.
Our flight operation manager tends to apply the more restrictive interpretation, using the planning minima even after lift off, at least when it comes to destination airports.
Let's make an example, which actually occurred to me recently.
Destination was Cannes, and in order to comply with the planning minima a headwind of at least 10 knots was required in order to land rwy 17.
The wind required was present in the forecast, and two alternates were selected. All the dispatch requirements were met.
During the descent to destination we checked the wind, which had decreased, falling below the minimum component necessary for us in the planning phase.
What were we supposed to do? It is actual phase now, and WITHOUT the 60% factorization we are able to take any runway, but WITH the factorization we shouldn't be landing.
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Dirk85, in your scenario you have been despatched legally, you are now indeed requiring inflight planning from that point onwards.
Generally inflight planning is more forgiving as it is not factored by 60%, but it IS taking the more actual conditions into account (not so at planning stage hence the factor is applied). Thus you do not need the 60% required at planning anymore, you are to apply inflight performance and thus can land in your scenario on any runway where inflight performance enables you to land on.
Generally inflight planning is more forgiving as it is not factored by 60%, but it IS taking the more actual conditions into account (not so at planning stage hence the factor is applied). Thus you do not need the 60% required at planning anymore, you are to apply inflight performance and thus can land in your scenario on any runway where inflight performance enables you to land on.
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Skyjob, what about the paragraph that states... Before commencing an approach to land at the destination aerodrome, the commander shall check that a landing can be made in full compliance with (a) to (d) and CAT.POL.A.225.
Point (a) clearly refers to the 60% factorization, clearly introducing in the inflight re-planning phase all the rules typical of the dispatch phase.
Point (a) clearly refers to the 60% factorization, clearly introducing in the inflight re-planning phase all the rules typical of the dispatch phase.
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See the GM1 for CAT.POL.A.230, clear indicating the reference to planning by using words such as determining, planned and expected.
Actual conditions are used inflight, not planned ones...
GM1 CAT.POL.A.230 Landing — dry runways
LANDING MASS
CAT.POL.A.230 establishes two considerations in determining the maximum permissible landing mass at the destination and alternate aerodromes:
(a) Firstly, the aeroplane mass will be such that on arrival the aeroplane can be landed within 60 % or 70 % (as applicable) of the landing distance available (LDA) on the most favourable (normally the longest) runway in still air. Regardless of the wind conditions, the maximum landing mass for an aerodrome/aeroplane configuration at a particular aerodrome cannot be exceeded.
(b) Secondly, consideration should be given to anticipated conditions and circumstances. The expected wind, or ATC and noise abatement procedures, may indicate the use of a different runway. These factors may result in a lower landing mass than that permitted under (a), in which case dispatch should be based on this lesser mass.
(c) The expected wind referred to in (b) is the wind expected to exist at the time of arrival.
LANDING MASS
CAT.POL.A.230 establishes two considerations in determining the maximum permissible landing mass at the destination and alternate aerodromes:
(a) Firstly, the aeroplane mass will be such that on arrival the aeroplane can be landed within 60 % or 70 % (as applicable) of the landing distance available (LDA) on the most favourable (normally the longest) runway in still air. Regardless of the wind conditions, the maximum landing mass for an aerodrome/aeroplane configuration at a particular aerodrome cannot be exceeded.
(b) Secondly, consideration should be given to anticipated conditions and circumstances. The expected wind, or ATC and noise abatement procedures, may indicate the use of a different runway. These factors may result in a lower landing mass than that permitted under (a), in which case dispatch should be based on this lesser mass.
(c) The expected wind referred to in (b) is the wind expected to exist at the time of arrival.
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I would totally agree with you, and I think that planning phase should be separated from actual phase, but you did not answer the question.
That paragraph that I quoted you clearly talks about factorization, making reference to full compliance with CAT.POL.A.230 from point (a) to (d), which includes the 60% factor, and before commencing the approach, which indicates without a doubt an in-flight situation.
To be noted that this seems to apply only when a particular wind component is necessary in order to meet the above requirements (i.e. you comply with (e)(2) but not (e)(1)), and is coherent with the example of Cannes I made before.
Different would be if the plane does not meet point (e)(2) in planning phase, but comply with (e)(1): in that case once in-flight you are not required to meet any dispatch minima and you can use the unfactorized values from the AFM.
That paragraph that I quoted you clearly talks about factorization, making reference to full compliance with CAT.POL.A.230 from point (a) to (d), which includes the 60% factor, and before commencing the approach, which indicates without a doubt an in-flight situation.
To be noted that this seems to apply only when a particular wind component is necessary in order to meet the above requirements (i.e. you comply with (e)(2) but not (e)(1)), and is coherent with the example of Cannes I made before.
Different would be if the plane does not meet point (e)(2) in planning phase, but comply with (e)(1): in that case once in-flight you are not required to meet any dispatch minima and you can use the unfactorized values from the AFM.
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This is fascinating stuff. I've read earlier threads on this subject and must admit I'd always assumed there was nothing in it.
I think the question here though is: what evidence is there that the interpretation made by dirk85's Ops Manager is wrong?
It's not clear to me where the distinction between pre-dispatch planning and inflight planning comes from?
Why does anyone think operators don't need to use the factored totals after dispatch?
I think the question here though is: what evidence is there that the interpretation made by dirk85's Ops Manager is wrong?
Originally Posted by dirk85
I spoke about this matter with many colleagues, and still was not able to find an agreed solution.
Our flight operation manager tends to apply the more restrictive interpretation, using the planning minima even after lift off, at least when it comes to destination airports.
Our flight operation manager tends to apply the more restrictive interpretation, using the planning minima even after lift off, at least when it comes to destination airports.
It's not clear to me where the distinction between pre-dispatch planning and inflight planning comes from?
Why does anyone think operators don't need to use the factored totals after dispatch?
Last edited by JonDyer; 22nd Dec 2014 at 14:59. Reason: lack of clarity
This issue is a grey area in regulation (deliberately?) and is open to interpretation.
The operator (Captain) is responsible for safe operation, there is a reminder of this in the OPS section – before landing assessment. There may also be other assumptions in the regulations (including CS25), but the final judgement is that of the Captain before landing.
Providing you can justify the choice of action as being safe then all is well, but if the chosen data is less than the established safety margin based on the dispatch data, then with hindsight after an incident, the decision could be debatable. The debate would be about the equivalent level of safety, and thus that there should not be a gap between dispatch and pre landing.
Many manufactures provide ‘actual’ data which requires considerable knowledge of what the data implies and then requires assessments, additions, or adjustment in correctly recognising contributing factors. If assessed correctly, and appropriate safety margins are added, then the pre landing check using ‘actual’ distances should be close to the dispatch case.
Airbus, for one, now publishes Operational Landing Distances (OLD), more often with a Factor (FOLD) – check what the factor is - which provide more realistic and achievable landing distance for the conditions. There are still provisions such as the reported runway conditions are reasonably accurate (Captain decision again).
In many situations (most?), FOLD should closely agree with the dispatch data, thus the pre landing FOLD data could be deemed ‘safe’.
But then the crew still has to fly the aircraft according to the assumptions in the data.
The operator (Captain) is responsible for safe operation, there is a reminder of this in the OPS section – before landing assessment. There may also be other assumptions in the regulations (including CS25), but the final judgement is that of the Captain before landing.
Providing you can justify the choice of action as being safe then all is well, but if the chosen data is less than the established safety margin based on the dispatch data, then with hindsight after an incident, the decision could be debatable. The debate would be about the equivalent level of safety, and thus that there should not be a gap between dispatch and pre landing.
Many manufactures provide ‘actual’ data which requires considerable knowledge of what the data implies and then requires assessments, additions, or adjustment in correctly recognising contributing factors. If assessed correctly, and appropriate safety margins are added, then the pre landing check using ‘actual’ distances should be close to the dispatch case.
Airbus, for one, now publishes Operational Landing Distances (OLD), more often with a Factor (FOLD) – check what the factor is - which provide more realistic and achievable landing distance for the conditions. There are still provisions such as the reported runway conditions are reasonably accurate (Captain decision again).
In many situations (most?), FOLD should closely agree with the dispatch data, thus the pre landing FOLD data could be deemed ‘safe’.
But then the crew still has to fly the aircraft according to the assumptions in the data.
Thread Starter
Why does the 60% of LDA apply in only one instance?
Dirk85 has raised a great example.
CAT.POL.A.230 (f) is clearly relevant in this case. Putting everything into plain English: if there is only one runway, and you need a specific headwind component to land on it because in still winds your ODP performance shows it to be too short, you have to ensure that your landing performance allows you to comply with the requirements of CAT.POL.A.230 Landing (a) - (d) before commencing the approach.
Why only this one case? If you're airborne, and in every other case we can supposedly disregard the requirements of (a) - (d), what is the benefit of applying those requirements in this one case? Why would the requirements of (a) - (d) apply to only that one, specific situation?
My understanding remains that Performance Class requirements takes precedence over CAT.POL.A.105 (a)(1), and the requirements of CAT.POL.A.230 Landing (a) - (d) are applicable. In the case outlined in (f) I believe that this is merely reinforcing the requirements as in that specific situation a given wind component is required in order to ensure the necessary commercial safety factors; and these factors, most pertinently the 50% HW component, are applicable.
I've not seen a convincing argument against how I've comprehended this part of IR-OPS, but I'll add the caveat that I have made being wrong into an art form...
CAT.POL.A.230 (f) is clearly relevant in this case. Putting everything into plain English: if there is only one runway, and you need a specific headwind component to land on it because in still winds your ODP performance shows it to be too short, you have to ensure that your landing performance allows you to comply with the requirements of CAT.POL.A.230 Landing (a) - (d) before commencing the approach.
Why only this one case? If you're airborne, and in every other case we can supposedly disregard the requirements of (a) - (d), what is the benefit of applying those requirements in this one case? Why would the requirements of (a) - (d) apply to only that one, specific situation?
My understanding remains that Performance Class requirements takes precedence over CAT.POL.A.105 (a)(1), and the requirements of CAT.POL.A.230 Landing (a) - (d) are applicable. In the case outlined in (f) I believe that this is merely reinforcing the requirements as in that specific situation a given wind component is required in order to ensure the necessary commercial safety factors; and these factors, most pertinently the 50% HW component, are applicable.
I've not seen a convincing argument against how I've comprehended this part of IR-OPS, but I'll add the caveat that I have made being wrong into an art form...
Only half a speed-brake
Hello again everyone,
I read your posts carefully, yet still I see no trouble, please help me understand where the percieved dilemma comes from.
Typically (think of alternate aerodrome planning minima..), there are dispatch conditions, which are more restrictive than what is in fact operationally required to land. Then:
You can land safely if ALD (actual landing distance) is less than LDA - in flight calculation requirement. To put some margin in, the regulations require us to use ALD*1,6 coefficient in the dispatch phase. Thus: a) on purpose we dramatically reduce the statistical probability of really needing to land at ALD=LDA; b) if WX/MX/ conditions change unpredictably whilst airborne, the pilots are still allowed to use the full certified capabilities of the A/C without the 1,6 margin restraining them.
The NORMAL situation
1) big margins needs to be applied to dispatch
2) once in flight, as long as ALD < LDA, you may land "WHATEVER".
(statistical approach to hazards and risks)
I understand (f1) correctly, it provides - for a specific set of conditions - a waiver to the principle above:
So the ALTERNATIVE situation
1) the big margins normally in force (dispatch requirements) can be circumnavigated
(2 alternates et al.)
2) but only if you promise to adhere to them before starting the approach. Which is not normally the case required.
To summarize:
A) The regulators ask us to use a hazard filter (ALD*1,6 at dispatch), and then allow us to operate all the way to the limits (in-flight: ALD <= LDA) if the situation requires so.
B) The regulators via (f1) allow us to depart with special provisions (two alternates) without the 1,6 "hazard filter" applied yet, but we still need to show compliance before commecing to land.
I read your posts carefully, yet still I see no trouble, please help me understand where the percieved dilemma comes from.
Typically (think of alternate aerodrome planning minima..), there are dispatch conditions, which are more restrictive than what is in fact operationally required to land. Then:
You can land safely if ALD (actual landing distance) is less than LDA - in flight calculation requirement. To put some margin in, the regulations require us to use ALD*1,6 coefficient in the dispatch phase. Thus: a) on purpose we dramatically reduce the statistical probability of really needing to land at ALD=LDA; b) if WX/MX/ conditions change unpredictably whilst airborne, the pilots are still allowed to use the full certified capabilities of the A/C without the 1,6 margin restraining them.
The NORMAL situation
1) big margins needs to be applied to dispatch
2) once in flight, as long as ALD < LDA, you may land "WHATEVER".
(statistical approach to hazards and risks)
I understand (f1) correctly, it provides - for a specific set of conditions - a waiver to the principle above:
If the operator is unable to comply with (e)(1) for a destination aerodrome having a single runway where a landing depends upon a specified wind component, the aeroplane may be dispatched
1) the big margins normally in force (dispatch requirements) can be circumnavigated
(2 alternates et al.)2) but only if you promise to adhere to them before starting the approach. Which is not normally the case required.
To summarize:
A) The regulators ask us to use a hazard filter (ALD*1,6 at dispatch), and then allow us to operate all the way to the limits (in-flight: ALD <= LDA) if the situation requires so.
B) The regulators via (f1) allow us to depart with special provisions (two alternates) without the 1,6 "hazard filter" applied yet, but we still need to show compliance before commecing to land.
Last edited by FlightDetent; 22nd Dec 2014 at 19:37. Reason: Grammar help from a friend
It is not grey but it is not obvious, the rule needs to be correctly interpreted and note that the CAT.POL.A.230 directs that the landing mass refers to CAT.POL.A.105A, is at the start of the takeoff or an inflight re-plan. That is it is a planning function.
CAT.POL.A.230 Landing — dry runways
a) The landing mass of the aeroplane determined in accordance with CAT.POL.A.105(a) for the estimated time of landing at the destination aerodrome and at any alternate aerodrome shall allow a full stop landing from 50 ft above the threshold:
1) for turbo-jet powered aeroplanes, within 60 % of the landing distance available (LDA);
a) The landing mass of the aeroplane determined in accordance with CAT.POL.A.105(a) for the estimated time of landing at the destination aerodrome and at any alternate aerodrome shall allow a full stop landing from 50 ft above the threshold:
1) for turbo-jet powered aeroplanes, within 60 % of the landing distance available (LDA);
CAT.POL.A.105 General
(a) The mass of the aeroplane:
(1) at the start of the take-off; or
(2) in the event of in-flight replanning, at the point from which the revised operational flight plan applies, etc
(a) The mass of the aeroplane:
(1) at the start of the take-off; or
(2) in the event of in-flight replanning, at the point from which the revised operational flight plan applies, etc
Last edited by c100driver; 22nd Dec 2014 at 19:52. Reason: reword to beter englash
Moderator
This one crops up regularly and one can only have empathy with those endeavouring to find black and white answers floating somewhere in the grey porridge.
Consider -
(a) the Certification Standards (ie what the AFM says) have stood a reasonable test of time under fire so, as a first approximation, they represent a reasonably good risk approach for the general case.
(b) in an emergency situation of one kind or another - which impacts on landing performance - the normal standards may, or may not, be feasible and the commander has to come up with a recovery plan for the situation. He/she is expected to use all available resources and information in determining what the gameplan is to be ..
(c) if the result at the end of the day is less than desirable the operator and crew (commander in particular) can expect censure of some sort according to jurisdiction
(d) all the relevant players, presuming survival for the crew, can expect to be quizzed aggressively as to their decisions and actions .. food for thought ?
(e) if you don't have a really good story .. you may find yourself in a state of unpleasantness. The Sydney collision mishap in the early 70s, while not directly relevant to the landing problem, illustrates the detailed Monday morning quarterbacking to which the parties may be subject and strikes me as a salutary lesson in after-the-event activities. Although the memory is fading on the specifics of this one, my recollection is that the subsequent damages action resulted in an approximate three-way damages split for the relevant parties .. which included the B727 commander.
(f) what to do ? - my suggestion, regardless of rules and however you may choose to interpret the State protocols, is
(i) if you CAN recover in compliance with the Standards, why would you place yourself and your passengers at jeopardy by accepting a more critical requirement ? After the subsequent mishap (which may not be related directly to the decision) what will be your story in Court ? You can bet your superannuation and house on opposing counsel's endeavouring to assign much importance to that decision ..
(ii) if no compliant recovery solution be available, one needs to have done (within the time constraints on the day) relevant and defensible risk assessments to arrive at the apparently best solution. Again, expect to be quizzed mercilessly if things don't go according to plan.
(iii) if there is no sensibly desirable strategy available the folk on the spot just have to do their best .. sometimes the outcome appears to be miraculous (eg Sioux City and the Hudson River) while, with others, the crew is largely taken out of the loop (eg O'Hare and various midair collisions).
In all cases there will be all the time in the world for the subsequent witch hunt to explore the minutiae of the history.
That the commander may only have had seconds just reflects the basic unfairness of life at times ..
once in flight, as long as ALD < LDA, you may land "WHATEVER".
That's a very brave outlook on risk management. In my view the result is a near foregone conclusion which the crew may reflect upon while sitting in the weeds (or worse) somewhere in the overrun or beyond ... If emergency considerations provide no feasibly preferred option, so be it, but one had best have that decision process neatly tied up in bows for the Inquiry.
Consider -
(a) the Certification Standards (ie what the AFM says) have stood a reasonable test of time under fire so, as a first approximation, they represent a reasonably good risk approach for the general case.
(b) in an emergency situation of one kind or another - which impacts on landing performance - the normal standards may, or may not, be feasible and the commander has to come up with a recovery plan for the situation. He/she is expected to use all available resources and information in determining what the gameplan is to be ..
(c) if the result at the end of the day is less than desirable the operator and crew (commander in particular) can expect censure of some sort according to jurisdiction
(d) all the relevant players, presuming survival for the crew, can expect to be quizzed aggressively as to their decisions and actions .. food for thought ?
(e) if you don't have a really good story .. you may find yourself in a state of unpleasantness. The Sydney collision mishap in the early 70s, while not directly relevant to the landing problem, illustrates the detailed Monday morning quarterbacking to which the parties may be subject and strikes me as a salutary lesson in after-the-event activities. Although the memory is fading on the specifics of this one, my recollection is that the subsequent damages action resulted in an approximate three-way damages split for the relevant parties .. which included the B727 commander.
(f) what to do ? - my suggestion, regardless of rules and however you may choose to interpret the State protocols, is
(i) if you CAN recover in compliance with the Standards, why would you place yourself and your passengers at jeopardy by accepting a more critical requirement ? After the subsequent mishap (which may not be related directly to the decision) what will be your story in Court ? You can bet your superannuation and house on opposing counsel's endeavouring to assign much importance to that decision ..
(ii) if no compliant recovery solution be available, one needs to have done (within the time constraints on the day) relevant and defensible risk assessments to arrive at the apparently best solution. Again, expect to be quizzed mercilessly if things don't go according to plan.
(iii) if there is no sensibly desirable strategy available the folk on the spot just have to do their best .. sometimes the outcome appears to be miraculous (eg Sioux City and the Hudson River) while, with others, the crew is largely taken out of the loop (eg O'Hare and various midair collisions).
In all cases there will be all the time in the world for the subsequent witch hunt to explore the minutiae of the history.
That the commander may only have had seconds just reflects the basic unfairness of life at times ..
once in flight, as long as ALD < LDA, you may land "WHATEVER".
That's a very brave outlook on risk management. In my view the result is a near foregone conclusion which the crew may reflect upon while sitting in the weeds (or worse) somewhere in the overrun or beyond ... If emergency considerations provide no feasibly preferred option, so be it, but one had best have that decision process neatly tied up in bows for the Inquiry.
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I buy FlightDetent's explanation.... ONE runway being with only one landing direction available. Hence, very special circumstances and to prevent the operation to routinely circumvent the dispatch requirement, by selecting 2 alternates, to an airport that basically can never be used according to the dispatch criteria.
What is practical is another discussion (one landing direction or not). Our performance software naturally calculates dispatch and inflight distances. However, if the dispatch requirement can't be met, it outputs "Landing weight too high for LDA", and doesn't calculate inflight either.
So what to do?? Flying into e.g. a 1700 meter runway, in a 738, fully loaded and with wet runway: Dispatch requirement is 1900 meters, ALD is 1300 (approx. values from the top of my head, don't beat me up if the percentages don't add up).
Software refuses to make any calculations! Solution is to chose another airport, with a longer runway and with similar pressure altitude and slope. I presented this problem to my Director of Flight Ops, and his reply was: "if it is wet, when you arrive, I recommend you divert!". If he doesn't want to take the chance, why should I?
400 meter margin may sound like a lot, but is it? Those ALD performance figures are not real, they were never demonstrated properly. The aircraft manufacturer is allowed to combine the best segments from different flights: Best flare, best touch down, best braking - and add each up a combined ALD. The PERFECT (unachievable) landing, made by a test pilot, with no regard for pax comfort and probably with little fear of making a hard landing and damage to the aircraft. Probably they had perfect tires and brakes installed as well.
Do you really want to try replicate than?
Personally, I do not need to sh!t my pant, and max effort braking coming to a halt with the nose hanging over the opposite approach lights.
What is practical is another discussion (one landing direction or not). Our performance software naturally calculates dispatch and inflight distances. However, if the dispatch requirement can't be met, it outputs "Landing weight too high for LDA", and doesn't calculate inflight either.
So what to do?? Flying into e.g. a 1700 meter runway, in a 738, fully loaded and with wet runway: Dispatch requirement is 1900 meters, ALD is 1300 (approx. values from the top of my head, don't beat me up if the percentages don't add up).
Software refuses to make any calculations! Solution is to chose another airport, with a longer runway and with similar pressure altitude and slope. I presented this problem to my Director of Flight Ops, and his reply was: "if it is wet, when you arrive, I recommend you divert!". If he doesn't want to take the chance, why should I?
400 meter margin may sound like a lot, but is it? Those ALD performance figures are not real, they were never demonstrated properly. The aircraft manufacturer is allowed to combine the best segments from different flights: Best flare, best touch down, best braking - and add each up a combined ALD. The PERFECT (unachievable) landing, made by a test pilot, with no regard for pax comfort and probably with little fear of making a hard landing and damage to the aircraft. Probably they had perfect tires and brakes installed as well.
Do you really want to try replicate than?
Personally, I do not need to sh!t my pant, and max effort braking coming to a halt with the nose hanging over the opposite approach lights.