Required landing distance available. Does inflight requirement exist?

[Vaneev]

My question to pilots who fly in accordance with JAR–OPS.
Below I quote JAR–OPS requirements (in short)
Please, tell me does this requirements only for dispatch, or they are valid, when pilot in flight make a decision to land or not to land?
If special inflight requirements exist, please quote.

Thank you in advance.

JAR–OPS 1.515 Landing – Dry Runways
(a) An operator shall ensure that the landing mass of the aeroplane... allows a full stop landing from 50 ft above the threshold:
(1) For turbo-jet powered aeroplanes, within 60% of the landing distance available;

JAR–OPS 1.520 Landing – Wet and contaminated runways
(a) An operator shall ensure that... runway... may be wet, the landing distance available is at least 115% of the required landing distance, determined in accordance with JAR–OPS 1.515.
(b) An operator shall ensure that... runway... may be contaminated, the landing distance available must be at least the landing distance determined in accordance with subparagraph (a) above, or at least 115% of the landing distance determined in accordance with approved contaminated landing distance data or equivalent, accepted by the Authority, whichever is greater.

[Denti]

Hmm, as the EU does not fly according to JAR-OPS anymore there are only very few countries that might still use them. Dunno if EU-OPS differs there much to be honest, and come april we gonna have the all new EASA-OPS.

[Vaneev]

I am sorry. I repeat my question regarding to EASA-OPS (content has not changed )

CAT.POL.A.230 Landing — dry runways

(a) The landing mass of the aeroplane ... 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.235 Landing — wet and contaminated runways

(a) When ... the runway ... may be wet, the LDA shall be at least 115 % of the required landing distance, determined in accordance with CAT.POL.A.230.

(b) When ... the runway ... may be contaminated, the LDA shall be at least the landing distance determined in accordance with (a), or at least 115 % of the landing distance determined in accordance with approved contaminated landing distance data or equivalent, whichever is greater.

[safetypee]

In this regard, EU-OPS 1 is sufficiently similar to JAR-OPS 1 for an interpretation to be the same; note ‘interpretation’.

There is little regulatory guidance (EASA) on how the dispatch / pre-landing (in-flight) assessment of landing distance should be equated. However, recent UK CAA advice clearly outlines their interpretation:-

“Before commencing an approach, the commander is required to ensure that a safe approach and landing can be made given the updated meteorological and runway surface condition (see EU-OPS 1.400).
The operator is required to demonstrate that it can ensure safe operations, and by applying the same additional safety margin to the in-flight performance assessment as to the dispatch assessment demonstrates an equivalent level of safety.”

The quote is taken from Appendix 1 of Safety Notice SN–2011/016, Operations on Contaminated Runways. (www.caa.co.uk/docs/33/SafetyNotice2011016.pdf)
Although the document is titled ‘contaminated’ it provides a wide range of information of landing performance issues and safety, with obvious focus on operations on contaminated runway, which are allowed in EU-OPS (and CS-25).

Thus the in-flight decision to land should be based on the same landing distance factors as for dispatch.

[Geardownandlocked]

These requirements are incorporated in the QRH LDR (Landing Distance Required) table. So no need to do the calculations yourself. So we apply these requirements during flight. Only in case of emergency it is allowed to use the 'actual landing distance' tables.

So to answer your question, there is no difference between what dispatch might calculate, and what we use during flight.

I hope this answers your question!

[safetypee]

Geardownandlocked, I would add a caution to your general view.
Perhaps not all aircraft types or operators have factored landing distance available for all airports / runway conditions / landing configuration / mass.
e.g. the Boeing supplied QRH for the B737 only has actual distances. Thus some calculation is required before landing.

Also, there could easily be a difference between what dispatch has calculated and what should be considered before landing.
e.g. for dispatch EU-OPS 1 requires use of the most likely landing runway, and use of current / forecast conditions. Thus before landing the crew must assess the actual conditions for the planned landing; - the wind for the chosen runway, the runway state / braking action, crosswind (effect on braking).
This should not be a quick recheck of landing mass to give a go/no go solution, but an evaluation of the margin between the required and available distances to judge what additional factor is available. This provides a guide to the level of braking required, expected turn-off point, etc; and also guarding against some of the unknowns in landing – touchdown speed, position, actual runway friction, tyre conditions.

[de facto]

FAA QRH distances i believe are unfactored,JAA are.
Same as JAA include line up distance for torr,faa uses from brake release point.
Different regulatory bodies,different calculations...
ALWAYS calculate your landing distance,it avoids choosing inapproriate a/b settings,position awareness in low vis,and be confortable if last minute change to a shorter runway or if weather/runway conditions changed since dispatched.
Learn your extra distance based on your every day skills..

[FE Hoppy]

OPS 1.475
General
(a)An operator shall ensure that the mass of the aeroplane:
(1) at the start of the take-off; or, in the event of in-flight replanning
(2) at the point from which the revised operational flight plan applies, is not greater than the mass at which the requirements of the appropriate subpart can be complied with for the flight to be undertaken, allowing for expected reductions in mass as the flight proceeds, and for such fuel jettisoning as is provided for in the particular requirement.

An operator shall ensure that the approved performance data contained in the aeroplane flight manual is used to determine compliance with the requirements of the appropriate subpart, supplemented as necessary with other data acceptable to the Authority as prescribed in the relevant subpart. When applying the factors prescribed in the appro- priate subpart, account may be taken of any operational factors already incorporated in the aeroplane flight manual performance data to avoid double application of factors.
When showing compliance with the requirements of the appropriate subpart, due account shall be taken of aeroplane configuration, environmental conditions and the operation of systems which have an adverse effect on performance.
For performance purposes, a damp runway, other than a grass runway, may be considered to be dry.
An operator shall take account of charting accuracy when assessing compliance with the take-off requirements of the applicable subpart.


Landing — dry runways
(a) An operator shall ensure that the landing mass of the aeroplane determined in accordance with OPS 1.475(a) for the estimated time of landing at the destination aerodrome and at any alternate aerodrome allows a full stop landing from 50 ft above the threshold:
(1) for turbo-jet powered aeroplanes, within 60 % of the landing distance available; or
(2) for turbo-propeller powered aeroplanes, within 70 % of the landing distance available;

[Dream Land]

From a 2007 Boeing seminar:

Landing Distance and Runway Length Required
The landing distance is defined by FAR/JAR 25.125 to be the horizontal distance to come to a complete stop from a point 50 ft above the landing surface, assuming
• Airspeed at the runway threshold is VREF.
• A level, smooth, dry, and hard surfaced runway. • Airport altitude and standard day temperature. • 50% of the headwind or 150% of the tailwind. • Maximum manual braking.
• No reverse thrust.

[safetypee]

Dream Land, you appear to be intermixing certification and operational requirements.

The ‘Landing distance’ for certification is defined in FAR/CS 25; this is usually referred to as the un-factored landing distance. This is the ‘dry’ landing distance which the manufacturer establishes as the baseline for landing performance.

The ‘Required landing distance’ comes from the operational regulations (FAR 121 / EU-OPS) which require the operator to use factored distances depending on aircraft type (jet/prop) and the runway surface condition (dry/wet). In the EU there is a separate category for contaminated operations with different baseline standards and operational assumptions.

The central theme of the thread is if the factored distances required for dispatch also apply to the actual landing requirements. The wording of the operational regulations is not particularly clear, but in the EU it appears to be generally accepted that a factored distance based on actual landing conditions should be used.
A basis of this is the intent to achieve a level of safety for landing which is equivalent to that required for dispatch.

In the US, the certification and dispatch requirements are essentially the same, but the safety aspects and landing distance required in a pre-landing assessment are less clear. The advice in the advisory guidance SAFO 06012 (August 2006), is potentially confusing, but essentially requires:- (A) that operators conduct a pre-landing assessment, and (B) the landing distance required is at least 15% over the ‘actual landing distance’.
The ‘Actual landing distance’ is not necessarily the manufacturer’s un-factored distance or the dispatch distance, but some in-between value representing what best distance might be achievable by line crews, e.g. B 737 QRH 'actual distance'. It is not a fully factored distance, and thus even with 15 % margin this distance is probably less than the dispatch distance, and thus has a smaller safety margin.

A related Boeing presentation is here:- Slippery Runways (http://www.scribd.com/doc/75487636/Slippery-Runways)

[FE Hoppy]

The central theme of the thread is if the factored distances required for dispatch also apply to the actual landing requirements. The wording of the operational regulations is not particularly clear, but in the EU it appears to be generally accepted that a factored distance based on actual landing conditions should be used.

I think it's pretty clear isn't it. If you re-plan in flight you need it. If you don't re-plan you already have it. The only time it isn't required is when abnormal or emergency factors are used.

[safetypee]

FE Hoppy, :ok:
Unfortunately, discussions and experience has identified that several operators and many pilots do not interpret “or, in the event of in-flight replanning” as being applicable to planning an approach, as in requiring a reassessment of the conditions for landing – ‘it only applies to diversion’.
The above could also infer that many of these operators/crews did not consider reassessment being necessary either, - a quick check of the landing mass would be OK ! :sad:

[mutt]

I would read "Re-planning" to also cover re-release or redispatch, so you cannot use this procedure to get around the landing runway requirements, however if you have an inflight emergency, you can dump the aircraft on a non-factored runway length.

It was interesting to note that following the Swissair MD11, aircraft manufacturers started providing non-factored landing distances in their QRH's (FAA). that would lead me to believe that they dont want to take the legal responsibility of giving you a landing distance requirement greater than certification requirements.

[9.G]

New FAA TALPA concept addresses so-called operational landing distances. It's more realistic concept based on average piloting skills taking into account actual aircraft, weather and airdrome conditions. It's actual landing distance with a regulatory margins applied. It'll be manifested mid 2012. :ok:

[Geardownandlocked]

@safetypee

I was assuming that the table named QRH 'LDR' (note the 'R' - Required) implies that it is already factored, and this would be clear to anybody. Especially since there is also a table for the 'actual' landing distances. I see no reason to be cautious here. But I'm only familiar with my own company procedures.
You mention that the Boeing supplied QRH only mentions 'actual' landing distances. I suppose this would be because Boeing doesn't want to be between the regulatory organ and the airlines flying their planes. They just have the test results, which are used to calculate the 'actual' landing distances. Am I wrong to assume that all airlines would supply their pilots with a 'required' landing distance table? Because it would be a pain to calculate this every time before landing.

And ofcourse the circumstances under which dispatch, and the pilots before landing, would be different, resulting in a different calculated RLD, but I thought we were speaking about fundamental differences between the way dispatch calculates, and the way pilots calculate. To my best knowledge, there is no difference.

[safetypee]

Geardownandlocked, my caution was aimed at the industry wide issues, not your specific documents.

I don’t know why manufacturers don’t supply factored distances; perhaps due to the apparent differences in use between FAA and EU requirements.
To add to any confusion, the Boeing ‘actual’ distances which I referred to (B737 QRH) are not the same values as the certificated actual landing distances (AFM), this is because Boeing include reverse thrust and recommend the use of a different (but still short) airborne distance.

Re differences in dispatch and airborne calculations:
In the EU there should not be any difference in the method, and with the same data, nor in the result; but note that dispatch is usually on forecast conditions, whereas the crew must use actual conditions. Also some dispatch options can use still air.
In the US it is unlikely that the methods/distances will be the same, the in-flight calculated distances being shorter (ref SAFO 06012), but I am not sufficiently experienced with their system to be sure of the increased risk.

[safetypee]

9.G, my understanding of Operational Landing Distances (OLD) is that only a 15% margin (FAA) is applied; this is not equivalent to the factored landing distances discussed previously, instead more like the shorter Boeing ‘actual’ distances.
Although TALPA has been led by the FAA and US operators, EASA is taking an interest in the reporting matrix.

TALPA background - FAA conference 2006 - Runway Condition Determination, Reporting, and Report Dissemination Workshop (http://www.faa.gov/news/conferences_events/runway_cond/)

A more recent update - EASA conference 2010 - Workshop on Runway Friction and Aircraft Braking (www.easa.europa.eu/events/events.php?startdate=11-03-2010&page=Workshop_Runway_Friction_and_Aircraft_Braking)

Boeing and Airbus views are presented; Airbus provides good comparisons with EU OPS and FARs and a realistic view of operational landing distances (OLD).
Although Airbus support OLD, the concluding slides (23/25) notes many problems, not least introducing (more) risk.
Also, if the 15% margin were retained by the FAA and the full factored distance by EASA, then there would not be a level playing field for the manufacturers amongst EU vs FAA operators. FAR operations could claim a shorter distance from an in-flight reassessment, but EU operators could not.
This also raises the issue that although OLD with 15% margin might be shown to be equivalent to current EU requirements for landing distance, it may not be equivalent in safety as OLD uses reverse thrust (generally not considered in certification).
With the current poor overrun safety statistics it might be foolhardy to increase the risks during landing operations.

[9.G]

as everything else the factored Required LD is only applicable at dispatch unless overruled by operators OM. In flight only actual LD matters which, as pointed out, conform with the current legislation doesn't reflect the reality. Operational landing distance concept is much more than just a mere 15% factor. It's a fundamentally new approach to actual landing performance assessment not only on the line but during certification as well, in particular on contaminated RWY. Moreover it finally binds the operator to implement realistic assessments online on daily basis. As for reversers, well there're there to be used and if they do shorten the landing distance then I don't see any reason why it shouldn't be accounted for. :ok:

[safetypee]

9.G, I believe that your first two sentences relate mainly to FAR operations.

The exact components of Operational Landing Distances (OLD) are not entirely clear, nor are the applications. There are indications of differences between Boeing and Airbus, FAA and EASA.

AFAIK there is no intent to change the basis of the certificated landing performance (manufacturer’s actual distances). Thus OLD is only an operational issue, but to add to the confusion Airbus also refers to an 'operationally’ factored OLD (FOLD !) which appears to use a 15% margin. :confused:
Furthermore Airbus hints of an undisclosed ‘factored’ equivalent of OLD which could be used for dispatch. :confused: :confused: :confused:

‘As for reverse’: reverse thrust is not used to determine certificated landing distances unless the manufacturer can demonstrate a consistent high level of reliability – Midway and other accidents indicate why. The EU has a caveat for contaminated operations where reverse can be considered; the additional risk is mitigated by infrequent exposure to those operations. There are similar alleviations in AC121-195 for FAR wet runway operations with restrictions, but applications are few if any.

Whilst most operations use reverse, there is a tendency to rely on it, particularly in deteriorating conditions. Also, contaminated operations are increasingly being considered as ‘the norm’ without any other risk mitigation.

[Sir George Cayley]

Now the CAA are doing something

IN-2011/120: Winter Operations 2011/2012 Runway Contamination Assessment Trial | Publications | CAA (http://www.caa.co.uk/application.aspx?catid=33&pagetype=65&appid=11&mode=detail&id=4755)

[9.G]

safetypee, I'm afraid its applicable to both FAA and EASA In-flight assessment operational rules Current FAA and EASA rules make a generic statement regarding the need to assess landing performance in flight: “The commander must satisfy himself/herself that, according to the information available to him/her, the weather at the aerodrome and the condition of the runway intended to be used should not prevent a safe approach and landing”. No guidance is given on the criteria and factors to be taken into account for the determination of a safe landing distance. One needs to immerse into materia in order to comprehend the full picture. It's a whole topic with airbus consisting of a whole ebook. If someone wishes to deepen the knowledge that's the way to go. All I wanna say is OLD is a realistic assessment of the landing performance on particular day, runway, aircraft status and landing method. What's the use of some unrealistic figures on a sunny day in TOU, if you're in the grass covered with snow in MAN? Whereas OLD gives you a good idea of where you'll end on that occasion. It's REALISTIC and that's all it matters. :ok:

[safetypee]

Re ‘… its applicable to both FAA and EASA.’ I disagree.
The latest quoted text appears to be taken from the Airbus ‘Safety First’ magazine (Issue 10).
IMHO this does not represent the general view in Europe, and now that the UK CAA has provided leadership with the concept of equivalent safety (link @ #4), it may be difficult for any European Country, Operator, or Captain to choose otherwise. This is the central aspect of this thread.

Reading the two Airbus articles, it is possible that the chosen interpretation is biased towards an ‘engineering’ view of a future requirement to provide operational data. An engineering view is ideal for certification, which deals with actual landing distances, but the industry’s problem with in-flight landing distance assessment is very much an operational issue involving many aspects such as judgement of a poorly reported or unknown runway condition, the variability of the atmosphere, and ever-present weaknesses in human performance.

The concept of OLD is excellent, but the implementation, as with other aspects of TALPA, requires considerable thought.
Where the definition of OLD involves “… the maximum landing performance realistically achievable by a line pilot adhering to standard techniques”, it questions what standard of piloting performance will be acceptable for the tests, and how might this be repeated in operation. Similarly what are ‘standard techniques’; will operators always follow manufacturers’ SOPs.
Add to this the need to improve the accuracy of reported runway braking action or to measure the runway contaminants in order to determine the required landing distance, then there are opportunities for considerable deviation in the objective of achieving a safe landing.

The overall objective of TALPA is to improve all of these aspects, particularly for FAA operators who may not select the same pre-landing safety margins as in Europe.
It would be difficult to argue that Europe should lower its safety standard just to align with the FAA, particularly when FAR operators appear to have an extremely variable interpretation and application of apparently lower standards (SAFO).

The simplistic merits of OLD reduce the safety margin compared with factored distances; this may be justifiable in engineering terms – the technical aspects of landing distance. However, many if not the majority of the landing safety issues are human – operational issues which requires a considerable safety margin.
The operational issues could be further divided into the soft and hard skills; variability in the hard ones is partly offset by the existing distance factors (1.67, 1.92); “This factor accounts for the normal operational variability that can be expected in day to day service such that the chances of a landing overrun are remote.” (AIC 14/2006)
It is more difficult to quantify a safety margin for the soft skills which include assessment, judgement, and decision making; thus the industry continues its safety efforts with CRM, TEM, and ALAR Tool Kit.

If the industry accepts a safety reduction in one area then how is the safety balance to be maintained? It’s very difficult to change the human, but you can improve the conditions of work. Fully factored landing distances provide additional ‘working space’; safe and realistic.
Thus the need to maintain current safety margins, the landing distance factors, and pre-landing assessment.

Safety First 10 (page 8) http://www.ukfsc.co.uk/files/Safety%20Briefings%20_%20Presentations/Airbus%20Safety%20First%20Mag%20-%20August%202010.pdf

Safety First 12 (page 5) Safety First 12 (http://www.scribd.com/doc/62707861/Safety-First-12)

AIC 14/2006 Large Transport Aeroplanes - Landing Performance NATS | AIS - Home (http://www.nats-uk.ead-it.com/public/index.php%3Foption=com_content&task=blogcategory&id=161&Itemid=58.html)

[9.G]

safetypee, there's numerous explanatory material about landing performance and I don't intent to play a teacher here. However fact is RLD is applicable to dispatch ONLY whereas ALD is for in flight assessment. UK doesn't differ a bit from EU OPS all it says for contaminated RWY at the planning stage RLD is never lower than ALD wet. Application of additional safety margin, typically 15%, is recommended. If you ever used EFB you'd have seen 2 sections for landing performance one is for dispatch stating RLD and the other one for in flight showing ALD and they're shorter by bout 40%. I'll state it again there's NO EU OPS requirement to apply RLD in flight. TALPA rectifies that situation by creating guide line of a realistic ALD assessment thus increasing safety.:ok:

[safetypee]

9.G, again we appear to be a cross purposes, or at least are intermixing our views.
I may have assumed that it would be self-evident that the use of equivalent safety for contaminated operations would apply equally to normal operations; apologies for the double jump.

Thus why shouldn’t the view promoted by the CAA under the title Operations on Contaminated Runways relate to all normal landing operations?
The CAA’s guidance applies the principles of safety management, which if used more widely could reduce ambiguity in interpreting the need for a pre-landing assessment and the magnitude of the landing distance safety margin.
IMHO this will be a significant benefit to safety in an operational area littered with accidents and close calls.

I have not used an EFB, neither do I know what standard of performance such a system is based on, nor any assumptions in use. However, adding a 15% margin to EU contaminated data (perhaps calculated in a manner envisaged by OLD) is not the same level of safety as 15% added to the AFM actual distance in normal operations.

I agree that the UK guidance does not contradict any rule, but it does provide clarity in the use of RLD (in-flight) as a means of establishing a safe approach (1.450). The wording of EU OPS neither prohibits nor promotes RLD as a possible means of maintaining safety; there are no rules for this, but neither is TALPA a rule making concern.

Based on current understandings:-
For contaminated operations FOLD may not improve safety over existing EU OPS, but in the US there will be benefit (after rule-making). Both EU and US operations are likely to continue with the current elevated level of risk, but the EU mitigates this with infrequent exposure, the US currently does not.
For normal operations, FOLD may simplify the pre-landing assessment in EU OPS; similarly in the US, but until the FAA mandates a pre-landing assessment and the use of FOLD, then their normal operations could be exposed to a higher level of risk than in the EU, and even with FOLD the safety margin may be less than the factored distance.

A regulatory complication is the quest for EASA/FAA harmonization. The EU has cert and ops rules for contaminated and normal operations, but not so in the US (only normal ops). It would be unwise to change the EU requirements to accommodate a new US rule (incorporating OLD) if the resultant safety margins are reduced. Also, noting that the current FAA regulatory hold may be commercially driven.

[9.G]

The title of this thread is plain and clear to me. Required landing distance available. Does inflight requirement exist? The poster wants to now if such legally binding requirement exists? The answer is NO, there's NO such requirement in the EU OPS. However operator might elect to include such as a requirement in it's relevant documentation. Think logically of it. Why would EASA or FAA bother with TALPA spending time, manpower and money if there was a requirement for RLD in flight? In that case all one needs to do is simply check if RLD is less than LDA and that's it. Why to bother with ALD? In this case we wouldn't be able to complete the landing on quite a number of occasions. RLD is used in the assessment of suitability of airdrome for dispatch purposes at the planning stage and regulator applied their a safety margin for unforeseen circumstances. ALD is relevant after airborne to be able to assess a real landing performance. How else do you wanna know if you'll be able to stop within LDA on a diversion conducting overweight landing for medical emergency with dying pax in the back? Are you not gonna divert coz your RLD isn't equal to LDA but more than ALD? The only problem is, as we're well aware of, it's basically inadequate. To make it somewhat adequate FAA applies 15% margin. However fundamental problem lies with the determination method of ALD. It's nothing but a test pilot landing and doesn't reflect daily business. That's the conclusion, after several overruns, FAA and EASA came to and started to work on a new concept TALPA. Well, nuff of academical BS. I don't disagree with your common sense but regulations are clear. It's also very much a commander's decision regardless of applied margins regs or anything else. If I'm not happy bout the way the situation unfolds it's a no go, no matter what the numbers are saying. Experience sometimes overrules.:ok:

[safetypee]

Legality was the question, and as explained above the ‘legality’ is with the interpretation of the rules, particularly 1.450.
The UK CAA has provided an interpretation such that any other Authority, Operator, or Commander might be challenged to justify an alternative so that in the event of an accident, the lawyers would not be knocking at their door; now that is ‘legality’.

I prefer to think that the guidance material provides a basis for a Commander to judge a safety margin for landing and thus be comfortable with his/her responsibilities within the rule – but s/he still has to complete the ‘plan’, and that activity also requires experience.

[9.G]

EASA isn't UK CAA to start with and certainly UK CAA won't preach anything contrary to the common understanding of legal foundation in the industry. Do you really think airbus and Boeing would release the EFB with those modules and let the pilots assess landing performance with ALD if it wasn't legal? Come on mate, reading something into context and understanding it are different things.
Let's see a practical example:
you are flying to a RWY limited field landing performance wise. The forecast is for dry RWY conditions. RLD is 1670 M for dry conditions. LDA is 1700 M. Now you're getting ATIS and it's says RA thus RWY is wet. Your ALD as per QRH or EFB is 1150 M including the margin of 15% for wet and RLD logically would be 1930 m My only question is are you gonna land or divert? :ok:

[safetypee]

EASA isn’t UK CAA, or the other way round, but each EU State has responsibility for safety oversight and promotion. EU makes the law; EASA generates rules / specs, etc; EASA / State National Authorities implement the safety activities.

Most aircraft manufacturers publish ‘actual’ landing distance; there are several views of what ‘actual’ includes. The AFM certification distances are the theoretical ‘unachievable’ minimum. Boeing provides their version of ‘actual’ in the QRH which makes many assumptions, adjustments, and additions, this distance probably is the absolute minimum that a pilot could achieve, but for some operators the QRH includes a further 15% margin. The FAA refers to something similar in SAFO. I am not familiar with what Airbus publishes.

The numerical example is a classic ‘can we do this’ question, as opposed the primary, and overriding safety question, “should we be doing this”.
The answer depends on the situation; in abnormal / emergency situations some additional risk can be tolerated – you have to know what the risk is and what the acceptable limits are.
In normal operation, the risks of landing should be minimized with good planning and practice – the process of safety; the UK CAA guidance provides an acceptable method of achieving that objective, which can be applied to a range of landing operations.

[9.G]

I take it you've never been to DTM with LDA 1300 m in normal operation and yet there're numerous flights on both airbus and Boeing daily. Go figure! Nice rethoric on your side alas far fetched from reality! :ok:

[PEI_3721]

I like the ‘should we be doing this’ as opposed to ‘can we do this’ attitude.
The limited field landing example appears to be a simple question of comparing RLD and RLA, then agree / disagree with the discussions above.
The exact content of the RLD may not be known. Does it depend on reverse, max brake, accurate threshold crossing height / speed / touchdown position? What airborne distance is assumed? Are all of these aspects achievable, all at the same time?
If the details are not known then at least 15% margin is required, possibly more.

There are other important aspects required for a decision – what is the wind, how wet is the runway (reporting accuracies); is the runway grooved, are there rubber deposits; is there an overrun area?

For a safety assessment before landing, all of these are aspects must be known. If there is variability, or areas of inaccuracy, then additional safety margins should be added, these could very quickly add up to the same factors as used for dispatch, thus this might be a good minimum if a more accurate pre-landing assessment cannot be made.

I suppose that the simple answer is if the aircraft was scheduled to operate to this airport, and if the legal dispatch requirements were met with full factored distances, then a landing at the planned landing weight would have a good safety factor – at or near full dispatch factors plus/minus wind, and the advantage of thrust reverse. So why in the example is the ALD / RLD ‘so tight”?

[Denti]

It appears to be legal. However company regulations differ greatly between companies and some take a more conservative approach to that. For example we can not use any inflight calculated landing distance that is less than the dispatch landing distance in my outfit. Our operational factor is 20% (or greater on commanders discretion) instead of 15% and it is on top of any factor that might be used within the OEM data.

[FE Hoppy]

Hello,

I'm just checking my 737-800 information and here comes a strange conclusion:

-'Dispatch' required landing distance for a landing weight of 65T, F40, 0 ft pressure altitude, dry runway is: 1625m.

-QRH Performance Inflight advisory information 65T, dry runway, F40, sea level, no slope, no tailwind, no isa deviation, 5kts above Vref, 2 reversers max manual braking: 950m, to be multiplied by 1,15 (Thats what we are required to factor in in my company, I'm not sure if this is a general legal requirement?), so its 1093m.

So if I understand correctly, the current interpretation of the rules say that if I'm in flight, I can happily land a B737-800 on a 1100m runway because the 'Dipatch required landing distance does not apply in flight'?

I think you better have a very good reason to make an attempt on such a short runway (uncontained fire/smoke...). But according to my company, that should be ok!!!

Any thoughts on this?

Best regards,

Alpagueur

My question would be this:

If you dispatched to a runway which was 1.67 times your unfactored landing distance why are you now considering landing somewhere else?

If you have re-planned in flight you need the dispatch requirements at the time of re-planning. If you have a abnormality or emergency that requires immediate landing you will be applying the appropriate abnormal landing factor.

The only reason you would have a reduced margin in normal ops would be poor planning. Either an unexpected rain shower made the dry runway wet or incorrect fuel planning (could be due to winds or routing) makes you arrive heavier than planned. You aren’t suddenly going to lose all your margin without a reason.

[Pitch Up Authority]

It is extremely simple. If the legal margins required for dispatch did not exist 80% of the flights would end up in the grass. Same reasoning for in flight. Boeing QRH gives you the actual distance no factoring except 15% in case of slippery. You use it to plan where you ill leave the RWY for taxi AND you have to factor yourself.

In case of a non normal it’s a different story

[9.G]

imagine some of us do fly LAHSO ops which is pretty much standard at busy airports over in the US. You can have 13000 ft RWY it's irrelevant coz in LAHSO you ought to stop within declared LDA for LAHSO. Guess what, it's ALD you go with not RLD to assess your suitability for LAHSO. Sorry I forgot we shouldn't be doing all that non sense in commercial aviation. :ok:

[safetypee]

Most of this thread has been about the legal aspects, and many pilots appear to have a need to hide behind a legal statement.
For dispatch, the ‘law’ is explicit – an operator “shall” – as per Hoppy #8. This applies to destination and alternate aerodrome, and at the point from which the revised operational flight plan applies, i.e. between those two it includes the other runway.

Before landing, a commander “must” satisfy … ... will be safe (EU-OPS 400); again the ‘law’ is explicit. The only judgement is in what is safe; for views of that, read the ICAO Safety Management Manual, and then look for the legal trail to the State law re flying safely.

A QRH contains data and recommendations (no law), these have to be understood and applied – by adding your own justifiable safety margin, as per Pitch Up #36.

There is no hiding behind a legal statement, there’s no need to. Pilots, commanders have to bear responsibility for their decisions; choices of action have to be justified, first to ourselves then everyone else.

[9.G]

talking of legal aspects I should mention RTFQ principle. Bus drivers among us should be familiar with the QRH content of chapter 4 Landing distance without autobrake. I really wonder why airbus puts a little note there saying The above distances are given for use in flight. Before departure refer to FCOM. Damn you airbus how dare you being illegal some of us cry out loud. RTFQ would be airbuses builders reply, I can imagine. Mind you airbus, unlike boeing, is written by lawyers not pilots and not for pilots. A very nice little brochure called getting to grips with performance will shed some light for those interested. :ok:

[Denti]

Mind you airbus, unlike boeing, is written by lawyers not pilots and not for pilots.

Nice try, but wrong of course. It is the same for both and boeing manuals are written by lawyers for quite some now. Added to that the first edition is always produced by those that want the same procedure for the whole fleet without any need for differentiation between very different types.

The relevant QRH chapter is called "inflight performance", at least in our 737 QRH.

[Checkboard]

Imagine an airport with 2 runways... On arrival, the crosswind is out of limits for the main, long runway and instead you are given a shorter, less used, lets say 1000m runway perpendicular to the main one... This is a possible scenario I would think, no? Well I'm not gonna land there with a 737-800 at 65 tons...

Now you are in-flight, making an in-flight decision, you can use the actual conditions. If the main runway is out of limits due crosswind, then the crossing runway will have a 40 knot headwind. :hmm: No problem for your 1000m landing, then. ;)

Fair enough, but what's the abnormal landing factor for a 'low fuel' situation. There is none of course...

.. but with a low fuel situation, you aren't going to be 65 tons any more, are you? ;) You are, of course, now in the regime of using your command authority to ignore ANY rule prudent in an emergency.

as you start the flight/diversion to that (new) airfield, you can "throw away" your Dispatch distance as you only need QRH distance in flight...?? Which defeats the whole idea of having a Dispatch distance!

When you dispatch, in terms of fuel planning, you include a 5% contingency, no? This is a safety margin, and allows for change of winds, inflight weather diversions etc etc. If you use it, you don't divert - you continue and using this safety margin was "planned" for - that's why it's a margin.

The 67% (or 92%) margin for despatch on runway length is exactly the same. If is rains or you are a bit heavier - you aren't required to divert, as this was a despatch safety margin. The fact that it has reduced a bit in flight is what it was there for.

Of course, if that margin has reduced to the point where the commander no longer considers it safe to land (given their inflight calculation of the minimum the aircraft requires, and safety factors the commander thinks prudent due crew experience or whatever) then you don't land. Welcome to the command decision process!

[9.G]

moreover the actual decision to land is made on short final dependable on how situation unfolds. Having said that TALPA will account for RWY conditions, like residual rubber, among others which could be detrimental factor in some places even in light drizzle. I'd rather land in moderate rain in DTM with 1350 M LDA than in BOM in damp conditions coz boy you just go skating on a hydro pillow. How often did one see a airdrome been hammered with snow where ATC still reports BA medium till few minutes later it switches to unreliable. Experience and knowledge of local shortcomings as well as your aircraft influence the decision as much as regulatory aspects. Having said that I concur with the statement from check board: welcome to commander's decision making process. :ok:

[Pitch Up Authority]

I remember the day that we had 40 kts headwind. Besides the wind there are of course the gusts.

Now there are two issues here:

1. Accurate landing: very difficult
2. Passengers comfort: several idiots tried to land and the result was. Two pax suffered a heart attack and a couple wetted their pants.

I never even tried the approach.

From the post above I can only conclude that to be 100% sure, the only way I will board an aircraft when the wx is marginal is when I am flying myself.

Checkboard:Contingency is there to cater for inaccurate planning. You need it before starting the flight. Factoring is there for inaccurate landing, deviations from planned braking action. As with contingency, you need it BEFORE starting the flare.

[Checkboard]

you need it BEFORE starting the flare.
Not under EU or FAA rules.