Presentation on theme: "Managing Threats and Errors during Approach and Landing"— Presentation transcript:
1 Managing Threats and Errors during Approach and Landing This presentation provides an overview of the prevention strategies and personal lines-of-defense related to runway overruns. It is intended to enhance the reader's flight safety awareness but it shall not supersede the applicable regulations or airline's operational documentation; should any deviation appear between this presentation and the airline’s AFM / (M)MEL / FCOM / QRH / FCTM, the latter shall prevail at all times.In the interest of aviation safety, this presentation may be reproduced in whole or in part - in all media - or translated; any use of this presentation shall not modify its contents or alter an excerpt from its original context. Any commercial use is strictly excluded.The authors shall have no liability or responsibility for the use of this presentation the correctness of the duplication, adaptation or translation and for the updating and revision of any duplicated version.How to avoid a runway overrunThis presentation provides an overview of the prevention strategies and personal lines-of-defense related to runway overruns. It is intended to enhance the reader's awareness but it shall not supersede the applicable regulations or airline's operational documentation; should any deviation appear between this presentation and the airline’s AFM / (M)MEL / FCOM / QRH / FCTM, the latter shall prevail at all times.
2 Landing OverrunsThis presentation is primarily for self-study and reviews the threats and errors that could lead to a landing overrun. It provides guidance of how to manage threats and errors, thus how to avoid an overrun accident.A threat is usually a physical aspect that may affect the safety of an operation; an error is normally a consequence of human involvement either in the presence of threats or without any hazard present at all.A wet runway is a threat to a landing operation – more landing distance required.The failure of the crew to understand the need for more landing distance or to adjust the level of braking would be an error related to the threat.FAA - Over 70% of Part 121 landing overrun accidents investigated by the NTSB during the period occurred on wet runways.Australian Transport Safety Bureau Report - Between 1970 and early 1998 there were at least 111 landing overrun accidents worldwide involving ‘western-built jet airline’ aircraft. These accidents included:42 overruns in which the aircraft landed long and/or fast on water affected runways36 overruns in which there was an apparent or assumed normal touchdown on a water affected runway33 overruns in which the landing was long and/or fast on a dry runwayLoughborough University Report “A New Aircraft Overrun Database based on data from “English-speaking world”:Overrun rate has been constant at 2x10-7 ( two times ten to the minus seven) per movement (but higher in the UK)A high proportion of overruns involve near or over maximum weightsThree times as many overruns in landings than aborted takeoffsWet runways, contaminated runways and tailwinds are factors in many overruns, particularly landing long and fastNo statistical evidence that precision approach better than non-precisionApproach and landing phases of flight4% time, 20% fatalities, 40% threats, 53% accidentsExperience is what you learn just after you needed it.Speakers notes provide additional information, they can be selected by clicking the right mouse button, select Screen, select Speakers notes.This presentation can be printed in the notes format to provide a personal reference document.
3 Managing Threats and Errors during Approach and Landing Section 1 - Threats A threat or hazard is any situation, event, or circumstance that may affect the safety of flight:The effects of threats occur in the future – so plan aheadThreats are not errors, but they increase the potential for errorTrapAvoidSafe FlightThreatIdentifyThe process of managing threats involves:Identifying and classifying a threatAvoiding the threat or threat situationsTrapping the threat and resolving or mitigating any effects or consequencesThreat and error management is an active process that involves avoiding the threats or opportunities for error, detecting new threats or errors and mitigating their effects, and finally managing the consequences of any threats and error. Avoid Trap MitigateThreats are external situations that must be managed by the cockpit crew during normal, everyday flights. Such events increase the operational complexity of the flight and pose a safety risk to the flight at some level.Threats may be expected or anticipated; expected threats can be pre briefed. However, as unexpected threats occur suddenly and without any warning, there is no possibility for the crew to brief in advance.ICAO LOSA Manual: AN/761 Doc 9803
4 Landing ThreatsAnalysis of worldwide landing incidents showed that a landing overrun is more likely if:-The approach was fast and landing attempted in excess of Vref +15ktsThe approach was high, exceeding the recommended threshold crossing heightThe aircraft ‘floated’ or is held off the runway for a smooth touchdownThe touchdown point is ‘long’, often beyond the normal landing areaThe runway surface is wet or contaminatedThere is a tailwindAn analysis of recent worldwide landing overrun incidents reveals that an overrun is likely to be characterised by a fast, high approach with a prolonged ‘float’ and long touchdown onto a wet runway. The same study also shows that these incidents were by no means confined to landings onto ‘limiting’ runways. UK CAA AIC 11/98 “LANDING PERFORMANCE OF LARGE TRANSPORT AEROPLANES”TrapAvoidSafe FlightThreatIdentifyThese threats may result in an accident;they can be managed:DetectedAvoidedTrapped
5 Landing overrunA landing overrun occurs when the aircraft landing distance exceeds the distance available. The distance required to land and stop an aircraft is effected by many factors in each of four phases; any single factor or combination can create a threat that may result in an overrun.ApproachFlareControlStoppingThe manufacturers landing distance is based on crossing the threshold at 50 ft, at the landing reference speed, Vref.The runway is dry, with known friction coefficient.Maximum braking is applied after touchdown.Certificated landing distances have additional safety factors to account for operational variability and runway conditions.ControlApproachFlareStopThe minimum landing distance is established with various parameters set at specific values. For example, the height at the runway threshold is 50 ft, the runway is dry, and the reference landing approach speed, Vref. Maximum braking is applied after touchdown. This distance should be regarded as a theoretical minimum, requiring a high level of pilot skill under favourable conditions, and using a level of braking that would normally be considered excessive from the passenger comfort point of view.The minimum landing distance is factored – increased to obtain the flight manual landing distances. This factor accounts for the normal operational variability that can be expected in day-to-day service, (predominantly wet runway conditions and excess approach speed), such that the chances of a landing overrun are remote. This distance depends on:The landing weight;The altitude at the aerodrome;The temperature at the aerodrome;The slope of the runwayThe forecast wind componentUK CAA AIC 11/98,The distance is published in the AFM as the “AFM Landing Distance”Landing field length (landing distance factor) requirements are introduced in the operational regulations as dispatch limitationsFor turbojet powered aircraft on a dry runway, the required landing field length is 1/0.6 (1.67) times the landing distance, for both destination and alternate airports. The required distance for destination is further increased by 15% for a wet runway (1.67 * 1.15 = 1.92), but remains 1.67 for alternate airport.FAA FAR / JAR 25Thresholdheight
6 First – Plan AheadCarefully review the expected landing performance during the approach briefing. The pre-planned data uses forecasts and predictions made at the time of dispatch. Recheck these and consider:-Choice of runway – available length, surface condition, dry / wet / contaminated * Similar runway surfaces may not have the same level of frictionWind - a downwind landing can significantly increase landing distance. Factors of 150% are applied to the landing distanceMaximum landing weight allowed - note the considerable differences in allowable landing weight between into-wind and downwind landingsCheck how close (%) the actual landing weight is to the allowed landing weight; adjust the planned braking level accordinglyConsider any effects of non normal operations (MEL)Carefully recheck the pre-planned performance when landing at alternate or diversion airportsIn-flight re-check of Landing Performance An aeroplane’s suitability to land at the intended destination is predicted upon forecasts at the time of dispatch.If the flight has proceeded to the intended destination as planned, then it is unlikely that normal operational variability (eg reduced headwind components) will have significantly affected the fuel burn to the extent that a delayed landing (to achieve to forecast landing weight) becomes necessary to satisfy the landing performance requirements. However, any significant departure from the flight plan, such as an unscheduled diversion, would clearly justify a review of the landing performance. If such a diversion was as a result of an emergency condition which necessitated a prompt landing, then clearly this would be justification for contemplating a landing on a runway which, although near, could not fully accommodate the increase in LDR due to the failure condition. Such a decision requires a sound knowledge of the principles involved to make an assessment of the conflicting considerations.UK CAA AIC 11/98* Attempts to land on contaminated runways involve considerable risk and should be avoided whenever possible.
7 It's OK to Go Around Approach threats The most significant threats during the approach are:Fast approach airspeeds - in excess of the planned valueHigh groundspeeds – not appreciating wind effectsHigh and / or steep approach above the desired flight pathHigh energy is the combination of these conditions; early control of energy can reduce these threats:Plan and brief the approach; use ‘approach gates’ that define the distance or height where the correct airspeed and height (energy) must be achievedConsider the effect of any speed correction for:- Gusting wind, Windshear, and Icing conditions, recheck the landing distance required, adjust the planned braking level according to the ground speedAny wind or icing correction factors are normally added to Vref, not the calm air approach speed … Vref+5If windshear is suspected, consider holding until conditions improve or divert.Thinking about approach threats :i) level of threat to the safety of flight,ii) level of situational uncertainty,iii) availability of decision relevant information,iv) level of tension andv) level of time pressure.Pettitt (1995) five characteristics of a crisis.Seven important skills for threat management:1. identify problems or potential problems;2. recognise the need for actions;3. attempt to determine cause of discrepant information before proceeding;4. provide information in advance;5. note deviations;6. demonstrate ongoing awareness of mission status;7. demonstrate awareness of task before performance of self.Prince and Salas (1993)It's OK to Go Around
8 Approach managementA stabilised approach provides a basis for a good landing, it provides the crew with the optimum conditions to flare, land, and stop the aircraftAn approach must be stabilised by 1,000 ft in IMC and by 500 ft in VMC1. The aircraft must be on the correct flight pathOnly small changes in heading and pitch are required to maintain the correct flight pathThe aircraft speed is < Vref+20 kts, < Vref + 15 kts at the thresholdThe aircraft is in the landing configurationSink rate < 1,000 feet per minutePower setting appropriate for configurationAll briefings and checklists have been performedInstrument landing system (ILS) approaches - must be flown within the equivalent of one dot of the glideslope or localizerVisual approaches - wings must be level on final before 500 ftCircling approaches - wings must be level on final before 300 ftFSF ALAR Tool KitFlight Safety Foundation ALAR Tool Kit
9 It's OK to Go Around Landing Flare A fast approach and / or excess height at the threshold are significant threats to a safe landing:The speed element of energy is the most important threatEnergy ~ Mass x Speed 2 ( Energy is proportional to Mass x Speed x Speed )An extended flare leads to a long ‘deep’ touchdown, lengthening the landing and roll out distancesDe crabbing the aircraft in a crosswind uses up landing distanceAccurate speed and flight path control provides the optimum conditions for a flare. Aim to touchdown within the relevant fixed distance markers.Aircraft decelerate quicker on the ground than in the air.E=0.5*M*V*VIt's OK to Go Around
10 Flare managementCorrect airspeed gives consistent aircraft feel for all landingsAim for the ideal touchdown point on every landingAim for a ‘safe’ landing; not always a ‘soft’ landingDownhill slopes may give a long touchdownThreshold: less than Vref + 15, Height 50 ftNext - touchdown point and speed (7 kt loss)Touchdown within the relevant fixed distance makersFSF ALAR Tool Kit Chapter 8 Landing techniquesAirbus 1Getting to grips with performance1Amber threats - avoidFor every 10 ft excess height at the threshold, an additional 200 ft of runway is required.
11 Respect wet runway crosswind limits Control on the runwayAs soon as the aircraft is safely on the runway, commence the deceleration; brakes, spoiler, thrust reverse. Effective landing distance available may reduced due to:-Delayed nose-wheel loweringLate application of brakes or reverseFailed or late application of lift dump / spoilersThe ‘control’ phase of a landing is often overlooked, but when the aircraft is at its highest ground speed, any delay in deceleration uses significant landing distanceGraphic credit; AirbusRef Boeing Aero No.18 Apr 2002Respect wet runway crosswind limits100 kts uses 169 ft of runway every second
12 Manage deceleration threats Do not delay lowering the nosewheel. Braking depends on ground reaction, this requires all wheels on the runway.Automatic spoiler / brake may depend on ‘weight’ switchesMake a firm touchdown especially on a wet or contaminated runwayBe prepared for aquaplaning with ground speeds above9 x tyre pressureAnticipate increased rudder input to control any crosswind effectsCheck spoiler / thrust reverse deployment"Viscous hydroplaning can occur at any speed on a wet runway." Reference "January 1978 Boeing Airliner, Landing on Slippery Runways"Amber threats - avoidFor every 1 kt excess speed above Vref, an additional 2% of runway is required.
13 Stopping the aircraftThe main threats to stopping the aircraft is the lack of braking effectiveness; this depends on:-Level of brakingPlan and use of the required level of braking for the conditionsCommence braking at high speed, dissipate energy earlyUse full braking when required; safety before comfortRunway frictionWet runways have much lower friction levels than a dry runwayThe friction depends on the runway surface, materials, and conditionContamination (water, slush, snow, or ice) reduces friction to very low levelsPassenger comfort and brake wear considerations generally induce a reluctance to utilise the aeroplanes full braking potential. This is acceptable where other factors affecting stopping performance are favourable, for example when the braking action is good, and when the landing distance available is clearly not limiting. However, reduced braking will result in the reduction of the safety factors built into the scheduled landing distances and is not appropriate where the margin has been eroded for other reasons.Landing on Contaminated Runways A runway should be considered as being contaminated when it is covered with ice, snow, slush, or more than 3 mm of standing water. Attempts to land on contaminated runways involve considerable risk and should be avoided whenever possible. Ideally, if the destination aerodrome is subject to these conditions the departure should be delayed until conditions improve, or an alternate used. Advisory data in the Flight Manual or Operations Manual concerning landing weights and techniques on slippery or contaminated runways should be used to determine whether there is an adequate distance margin over and above the normal Landing Distance Required. Operators should ensure that runways which are promulgated as being ‘slippery when wet’ are annotated as such in their operations manual and that appropriate guidance (such as landing technique, maximum weight, maximum crosswind, minimum headwind) is given to pilots having to land in these conditions.UK CAA AIC 11/98Level of brakingBrake for safety not for comfortDo not leave braking until the end
14 Manage all threats - every landing Fast; above Vref+15High at the thresholdWet RunwayLong landingManagement:Plan - self briefing, crew briefingStabilised approach - through the gatesAdjust braking levels - wet runways, tailwind“A good landing Captain”Photo credit, AirbusOperation on runways contaminated with water, slush, snow, ice or other contaminants implies uncertainties with regard to runway friction and contaminant drag and therefore to the achievable performance and control of the aeroplane during take-off, since the actual conditions may not completely match the assumptions on which the performance information is based. Where possible, every effort should be made to ensure that the runway surface is cleared of any significant contamination.The performance information assumes any runway contaminant to be of uniform depth and density.The provision of performance information for contaminated runways should not be taken as implying that ground handling characteristics on these surfaces will be as good as can be achieved on dry or wet runways, in particular following engine failure, in crosswinds or when using reverse thrust.JAA NPA 14 Operation on Contaminated Runways – JAR / AMC
15 Managing Threats and Errors during Approach and Landing Section 2 - Errors are usually the result of past activities, they are consequences of an action or inactionreduce the margin of safety and increase the probability of accidents or incidentsErrors in situation awareness - not understanding the situation, which leads to a wrong decision; due to poor knowledge, time management, or lack of attentionDecision errors - choosing the wrong course of action; due to failures of discipline, memory, or training, or by violating rules and procedures, or giving in to peer pressurePhoto credit. AirbusErrors - are the result of past activities, they are consequences not causes. We have to acknowledge that humans make errors and that everything does not always proceed as expected.Crew error is defined as an action or inaction by the crew that leads to deviations from organizational or flight crew intentions or expectations. Errors in the operational context tend to reduce the margin of safety and increase the probability of accidents or incidents. Errors may be in non-compliance with regulations, Standard Operating Procedures (SOPs) and policies, or unexpected deviation from crew, company or ATC expectations. ICAO LOSA ManualThere are two major ways in which error may arise. People may:(a) develop a wrong interpretation of the problem, which leads to a wrong decision because they are solving the wrong problem—a situation awareness error, or(b) establish an accurate picture of the situation, but choose the wrong course of action—a course of action error. OrasanuHuman error is defined as action or inaction that leads to deviation from crew intentions or situational requirements such as policies, regulations, and standard operating procedures. Errors may lead to inadvertent violations of rules and are an inevitable result of human limitations. On the other hand, wilful violation of rules and procedures is not error and cannot be tolerated by any organization. How an organization deals with error and violations is a critical element of its culture. Thus, the success of a program is dependent on whether or not it is congruent with the organizational culture. This is why developers need to have an accurate understanding of the organizational culture while developing programs. Errors in the operational context tend to reduce the margin of safety and increase the probability of accidents of incidents (Helmreich, Merritt, & Wilhelm).
16 Error ManagementIt is human nature to make errors, thus error management is a vital safety device; the process is similar to threat management:Identify situations that could lead to errorsAvoid these situations and circumstances that promote errorsIdentify an error, trap the error, take corrective action, and check effectivenessERRORTrapAvoidSafe FlightIdentifyMost flying activities follow this process, many of the actions are subconsciousWe learn from errors, from our own and from other peopleError management requires conscious thought to provide awareness and understanding. Rules enable us to avoid hazards; procedures trap residual errorsJames Reason (1997) defines error management at the organizational level as having two components, error reduction and error containment. Error reduction consists of measures taken to limit the occurrence of errors while error containment consists of the measures taken to limit adverse consequences.Error management at the crew level is defined as actions taken either to reduce the probability of errors occurring (error avoidance) or to deal with errors committed either by detecting and correcting them before they have operational impact (error trapping) or to contain and reduce the severity of those that become consequential (error mitigation).It is also possible for crew actions to exacerbate the consequences of error.A task requiring a high degree of conscious thought, it cannot be performed concurrently with other tasks without risking error.1. Intentional non-compliance error: Willful deviation from regulations and/or operator procedures;2. Procedural error: Deviation in the execution of regulations and/or operator procedures. The intention is correct but the execution is flawed. This category also includes errors where a crew forgot to do something;3. Communication error: Miscommunication, mis-interpretation, or failure to communicate pertinent information among the flight crew or between the flight crew and an external agent (for example, ATC or ground operations personnel);4. Proficiency error: Lack of knowledge or psychomotor (“stick and rudder”) skills; and5. Operational decision error: Decision-making error that is not standardized by regulations or operator procedures and that unnecessarily compromises safety. In order to be categorized as an operational decision error, at least one of three conditions must have existed:• The crew must have had more conservative options within operational reason and decided not to take them;• The decision was not verbalized and, therefore, was not shared among crew members; or• The crew must have had time but did not use it effectively to evaluate the decision.
17 Not understanding the situation Pilots may fail to recognise an uncommon or deteriorating situation; there are many reasons for this:The visual scene is ambiguous – illusions, poor weather, not scanning instrumentsUnaware of runway conditions – landing risks mis-assessed or underestimatedWarning signs ignored - complacency, bad habit, lack of knowledgeLack of time – time available underestimated, rushed decision, “ press–on-itis ”No pilot intentionally chooses failureConservative errorFailureGo Around without needRecognise a common situationSuccessLand when you shouldRecognise an uncommon situationGo Around when you shouldFailure to recognise the situationHazardous ErrorLand when you should notWhat we think the situation is:Common UncommonThe actual situation:Common UncommonMany air line Captains have not experienced a significant error in their judgment. While the particular conditions of each flight segment change, the flight path, the choices, and the mission goals remain virtually constant. The experienced airline pilot develops a very high confidence in his or her ability to adapt to the changing conditions and achieve a consistent, successful goal. Over time, this becomes the standard that measures the quality of an airline pilot’s judgment. Consistent flight accomplishment is the task that airline pilots are experts at completing.On the other hand, because they are so rarely exposed to failure, many very experienced air carrier pilots are actually novices at detecting and rejecting failed decision paths. Perhaps, they possessed these skills earlier in their careers, but over the years, they lost them.Good judgment becomes a pilot’s ability to adapt to changing conditions and to achieve a consistent successful goal, not his or her ability to detect and respond to a failing decision path.It is precisely this inexperience, combined with confidence in their judgment which triggers the Recognition Trap. SwaugerFailure to recognise deteriorating situations.Swauger ‘The recognition trap’
18 Expecting ‘a situation’ No two landings are the same!The smallest change in conditions may overcome the planBecause one ‘marginal’ landing was successful does not mean that the next attempt will beAvoid complacency, you may not be able to land and stop: Yes an accident can happen to youDo not tolerate SOP deviation: Avoid short cuts or thinking that you know betterResist peer pressure:It is OK to Go AroundExpectation can reduce awareness. The downside of anticipation is that it can bias your hearing or seeing what is really there.Things that take longer are less likely to get done right. If you're doing something that takes a long time, it is less likely to get done correctly.Reliable systems aren't always reliable.It's hard to detect something that isn't there.Distractions come in many forms.Sheryl L. Chappell - NASA Aviation Safety Reporting SystemDiscipline attention controlSituation awarenessKnowledgeSkill sensing scanERRORTrapAvoidSafe FlightIdentifyFirst be aware of your errors, then other people’s errorsMonitor the environment, the aircraft and crew for changes or errors in the planAvoid hazardous error provoking situations
19 Do not judge the situation on just one parameter Situation AwarenessAvoiding situation assessment errors:Situation cues provide a mental model of what is happening; cues have to be sought out and understoodSee to understand; deliberately scan the situation to gain information, compare this with the expected or the normal parametersKnow what to see and when to see it; be aware of distractions, focus attention on landing threats and opportunities for error‘See to understand’Know what to see andwhen to see itGraphic credit, AirbusSituation assessment errors can be of several types: situation cues may be misinterpreted, misdiagnosed, or ignored, resulting in a wrong picture; risk (threat or danger) levels may be misassessed (Orasanu, Dismukes & Fischer, 1993); or the amount of available time may be misjudged (Orasanu & Strauch, 1993).Checklist:-What are the plane, path and people doing now?What is likely to be the state of each later?Finally, consider all the 'what if possibilities for each.Focus attention on details while keeping the big picture;Anticipate, stay ahead of the airplane consider contingencies, have a plan for the 'what if situations’;Predetermine who will watch what in busy times;Have a plan for handling distractions, especially malfunctions;Use all your team members for awareness;Create reminders.MANAGING SITUATION AWARENESS ON THE FLIGHT DECK or THE NEXT BEST THING TO A CRYSTAL BALLSheryl L. Chappell - NASA Aviation Safety Reporting SystemAirspeed, AltitudeRunway lengthSurface conditionsWind, WetDo not judge the situation on just one parameter
20 Acquiring Situation Awareness Important situation cues for landing are:The aircraft’s actual approach path and airspeed in comparison with the ideal flight path and the target air speedThe runway conditions, friction, and the required level of brakingThe landing distance available for the ambient conditions, the aircraft weight and configurationTailwindMaintain an accurate picture of the situation, check and recheck:-Stable approachOn speed & heightRunway conditionsLanding distance availableMonitor, humans have limits to how much we can see and hear at the same time. Be aware of what you need - ignore everything else.Evaluate, evaluate the status of the plane/path/people, comprehending what you see and hear; make an assessment of the status of each. This leads to an understanding of what the situation is now, this gives you situation awareness for the current state.Anticipate, a key to maintaining situation awareness is to anticipate; stay ahead of the airplane, project what is going to happen later.Consider Contingencies. Sometimes things happen that cannot be anticipated.ControlApproachFlareStop
21 Maintaining Situation Awareness Planning and think aheadCreate the plan in the landing briefing;Aircraft weight – speed – landing distance requiredSurface conditions – landing distance requiredWind – landing distance requiredReadjust the plan if conditions changeChange the course of actionBe aware that apparently familiar situations hide changeplanmonitorcompareCompare with the SOPLanding gates, stabilised approach, speed / ht over thresholdAnticipate the next part of the planGo Around if unstable, if missing a gate, or fast at the thresholdBeware of bad habits – do not deviate from the plan or SOPsChange the course of action if a rule is violatedPlan. The plan is comprised of the current and future states of the plane, the path, and the people. This plan is the foundation all crew members are building their situation awareness upon. The plan is constantly being updated based on the awareness activities. As a crew monitors, evaluates, anticipates, and considers contingencies they continuously modify the plan. Ensuring the entire crew has the same shared plan will ensure that they have a shared situation awareness.Focus on the right information at the right time. Keeping the priorities straight isa constant challenge, as this report describes.If something doesn't look or feel right, it probably isn't. There are many cues from our surroundings for which we cannot always identify the origin. These cues are very real. Don't ignore them, even when they only manifest themselves in a feeling of uneasiness.Watch out when you're busy or bored. We are less likely to detect something when we're busy attending to something else. We will also be less likely to detect something when we're bored. During times of low and high workload be more vigilant.Habits are hard to break. Highly trained flight crews have developed very complex habit structures. These enable you to perform all the tasks required to skillfully fly your aircraft. There are times when these habits can get in the way of safety. The best way to combat this natural tendency is to create a barrier (a checklist / approach gate/ reminder), so that you prevent or at least are aware of what you are doing.Situation AwarenessPlanMonitorCompare
22 Decisions – a course of action A course of action is the result of a decision. Errors occur due to failures of discipline, biased memory, or a weakness in trainingIn routine or time critical events, actions may become automatic; avoid bad habits - landing fast or long, be aware of tailwind, wet runway, low braking levelsMost flight activity uses a mixture of assessment and action; these are the basis of standard operating procedures (SOPs) – follow all SOPsComplex or unusual situations requires more thought; it is essential to have good situation awareness and knowledge, and ‘make time’ to thinkContinuing an approach after missing a stabilized approach criteria is not the correct course of action.Errors in choosing a course of action may be of several types. In rule-based decisions, the appropriate response may not be retrieved from memory and applied, either because it was not known or because some contextual factor mitigated against it. In choice decisions, options also may not be retrieved from memory, or only one may be retrieved when in fact multiple options exist. Constraints or factors that determine the adequacy of various options may not be retrieved or used in evaluating the options. Finally, the consequences of various options may not be considered. The decision maker may fail to mentally simulate the possible outcomes of each considered option. Creative decisions may be the most difficult because they involve the least support from the environment. The absence of available options means candidate solutions must be invented to fit the goals and existing conditions.”OrasanuThis one time (landing overrun), however, conditions are different. This time, the Good Pilots miss indications that they are in a failing situation (heavy weight, hot day, tailwind, etc.). They continue to believe that this approach is safe and manageable. The corrections that have worked hundreds of times in the past now fail to solve their problem. Sometimes, they will take extraordinary steps to make the approach look normal and familiar, even though the parameters are well out of tolerance. Instead of discarding the plan, they begin questioning their judgment. It is no longer an exercise of completing a familiar task. It has become personal. These Good Pilots view the situation as an impeachment of their aviation skills and professional reputation. Instead of ACCEPTING that the plan is not working, they question WHY it is not working and WHY they judged it so poorly. Their judgment and verification always worked in the past, so it shouldn’t be wrong now.SwaugerDecisions, judgmentKnowledgeDisciplineTrapAvoidSafe FlightERRORIdentifyIt's OK to Go Around
23 Know the Risks Risk = Threat or Error x Vulnerability x Consequence Landing risks may be mis-assessed which may bias judgment:Low awareness of personal vulnerability to error makingNot considering the consequencesLanding risks are bounded by knowledge:High energy approaches are high risk manoeuvresRespect boundaries of speed and height– Approach GatesRespect cross wind and tailwind limits– Company SOPsWet runways require more landing distanceAdjust braking levels to suit surface conditions– Personal SOPsDo not copy or repeat bad habits– Personal risk managementPilots who do not perceive the risks are more likely to engage in higher risk activities. Pilots with a low perception of risk tended to be involved in more hazardous events. This seems to agree with the finding that pilots with low risk perception are more tolerant of risks.Higher levels of experience and qualifications were associated with lower levels of perceived risk.It is far better to have a problem caused by pilot skill deficiencies than to have a problem caused by pilot personality traits, because the former are far easier to change than the latter. Deficiencies in pilot skill may be addressed through a variety of training interventions, and the mechanisms for developing and delivering these interventions are well established and understood. Further, pilots are generally receptive to initiatives aimed at improving their skill levels.Changing risk perception is not a straightforward undertaking, however, since the factors that influence risk perception are complex and confounded. It is probably not appropriate simply to raise everyone’s perception of risk. Rather, risk perceptions must be made more valid.Consider the interaction between a pilot’s perception of self and their perception of the world and the resulting decision – “Yes, I can do this,” or “No, I cannot do this.”attempts to change risk tolerance (a potentially massive undertaking) would be far less effective in reducing accidents than training pilots in risk recognition skillsAccidents may be prevented by improved pilot education regarding risk identification and management.FAA considerations for training researchKnowledgeProficiency in assessmentDiscipline attitudesPhoto credit, BAESYSTEMSConsequences?
24 Consider the Consequences Possible fatalities or severe injuriesProbable collateral damageProbable aircraft ‘hull loss’Certain disruption, delayConsequential costDented prideJAR Ops Contaminant DefinitionsDry Runway - A dry runway is one which is neither wet or contaminated, and includes those paved runways which have been specially prepared with grooves or porous pavement and maintained to retain “effectively dry” braking action even when moisture is present. !!!!!!Runway contaminated by standing water, slush or loose snow – A runway is considered to be contaminated when more than 25% of the runway surface area (whether isolated or not) within the required length and width being used, is covered by surface water, more than 3mm deep, or by slush, or loose snow, equivalent to more than 3mm of waterATC rely on runway friction devices and reports from other crews: Both can provide incorrect or confusing informationRunway Friction Measurement Devices: No International standard for Friction devices. Accuracy of friction devices depends on contaminant type and design of device. No correlation to Certification friction levels or IATA terminologyCrew Reports: Level of “friction” is based on retardation and is therefore aircraft typeSpecific: This data should provide information to allow the crew to make real time decisions based on:• current runway condition• effect of tailwind if permitted• effect of incremental speeds on Vref• margin to limiting weights.! How does this compare against ATC braking action or friction information• What does good mean >0.5? Good contaminated or dry runway• How do you correlate this subjective term to actual predicted performanceYOUR PERFORMANCE DATA REQUIRES YOU TO KNOW.Most overruns are accidents; fatalities, injury, damageThink about, and lower the risk factors before you have an accident
25 More knowledge - lower risk, better decisions Relative Landing Distances:Be aware of additive values:-Fast + 20%Tailwind + 20%Long flare + 30%High + 30%Wet + 40 %Manufacture’s minimum distance:Vref , 50 ft, dry, max brake.Certificationsafety factor+ 10kt fast+ 10kt tailLong flare or + 100ft at thresholdMax brake stop requires 115% of minimum dry distance, a reduced safety margin.A fast landing also reduces the safety margin, and in a tailwind, there may be none!The manufacturers minimum landing distance (the reference distance) is normally established from the runway threshold at 50 ft and from the reference landing speed, Vref.The landing is on a dry runway of known surface quality and friction coefficient.Maximum braking is applied after touchdown.Certificated landing distances have increased factors to account for operational variability and runway conditions.These factors vary with certification authority; 1.67 on a dry runway, 1.92 on a wet runway. Manufacturers publish or advise the use increased factors when operating on contaminated runways such as standing water, flooded, snow and slush. Attempts to land on contaminated runways involve considerable risk and should be avoided whenever possible. Recent research (DOT Canada) suggest that factors ranging from 2.2 to 2.5 are required on contaminated runways to ensure the equivalent level of safety when landing on a dry runaway.Experience has shown that the presence of such contaminants may under certain conditions adversely affect the accuracy of the friction values obtained by any of the currently available friction-measuring devices, be they of the CFME or the DEC variety. Since the credibility and accuracy of friction measurement is of paramount importance to the safety of aircraft operations, when contaminants exceed certain specified limits, or when they are present atall, friction measurements are not taken, eliminating the possibility of erroneous friction values.The following are conditions under which friction measurements may not relate to aircraft braking performance:* When the water on a pavement surface exceeds .04 inch (1 mm);* When water is present on top of an ice layer on the pavement surface, and its depth exceeds .04 inch (1 mm);* When there is presence of slush on the pavement exceeding 1/8 inch (3 mm);* When there is slush or wet snow on ice or compacted snow exceeding 1/8 inch (3 mm); or* When the depth of dry snow on the pavement surface exceeds 1 inch (2.5 cm).As long as friction measurements are taken under conditions that do not violate the above criteria, the results are accurate and credible and truly reflect the surface friction characteristics.An Evaluation of Winter Operational Runway Friction Measurement Equipment, Procedures, and Research submitted by the WINTER RUNWAY FRICTION MEASUREMENT AND REPORTING WORKING GROUP, FAA, DOT Canada January 25, 1995Wet runwayWet + Fast + TailwindWet + High + LongIce / slippery runway
26 More knowledge - lower risk, better decisions Friction coefficient of runway surfaces:Type of surface, condition of surface (rubber deposits) , dry, wet, contaminated0.20.40.60.81Dry, smoothWet, groovedWet, smooth50KIASRunway Friction Mu100Certification terminology Crew / ATC reportDRY _ _ _ _ _ _ _ _ _DAMP _ _ _ _ _ _ _ _ _WET _ _ _ _ _ _ _ _ _CONTAMINATEDWater Patches _ _Flooded _ _ _ _ICAO code_ _ _Good 5Med - good 4Med - fair 3Poor 2Nil 1Unreliable 9At low speed the braking friction varies with speed; at higher speed the friction is dominated by the runway surface and condition. The friction level of a Concrete runway is not as good as ‘black top’ Tarmac, which is not as good as ‘high friction course’ Tarmac. Beware of rubber deposits on all surfaces particularly on wet runways.The ICAO ‘ATC’ runway friction report codes relate to the surface conditions i.e ‘good’ on a wet runway relates wet stopping performance which is already degraded with respect to dry runway operations.NORMAL - Maximum energy stops possible with little deterioration in certified (dry) stopping distance.GOOD - More braking is available than will be used in an average airline type deceleration. If a maximum energy stop were attempted (wet), some distance in excess of certified stopping distance would be expected.FAIR - Sufficient braking and cornering force is available for a well-flown approach and landing using light braking. However, excess speed or long touchdown would result in an extremely low safety factor depending on runway length and crosswind component. Careful planning and good judgment are required.POOR - Very careful planning, judgment, and execution are absolutely essential. Crosswind becomes a "priority one" consideration. While a safe and successful approach, landing, and stop can be accomplished if all factors are favorable, there is little room for error. Care must be exercised in every aspect of the operation and a very careful evaluation of all conditions is necessary.Note: "Unreliable" will be reported when surface conditions do not permit a meaningful action value to be determined (i.e., standing water, slush, wet snow [potential hydroplaning]).“If the surface is affected by snow or ice and the braking action is reported as “good”, pilots should not expect to find conditions as good as on clean dry runway (where the available friction may well be greater than that needed in any case). The value “good” is a comparative value and is intended to mean that aeroplanes should not experience directional control or braking difficulties, especially when landing.” JAA WP061Refs: FAANASA B 737 Aircraft test results from 1996 joint winter runway friction measurement program. T Yeager, NASA LangleyDoT Canada Procedures for Accounting for Runway Friction on Landing TC 14082EDoT Canada Falcon 20 Aircraft Braking Performance on Wet Concrete Runway Surfaces No. TP 14273EFAR / JAR JAR-OPS1Braking Action Measurements, A Scott BAESYSTEMS, ERA Icing Workshop 21st Nov. 2002“Flight Safety Aerodynamics”, Aage RoedICAO Codes are relative to the runway conditions, thus good is only good for a wet runway, which may already have a reduced safety marginGrey areas: There is no overall accepted certification / operational correlation between mu meters and airplanesWater, Slush, Wet Snow, Dry Snow, Compacted Snow, Ice
27 Make the decision, your decision Decisions depend on:Understanding the situation – take a wider view of the situationKnowledge and risk assessment – compare the situation with SOPsIdentifying safe courses of action – don’t focus on just one optionChoose the safest option, and then take action to correct any errorDon’t depend on previous aircraft landing reports;braking effectiveness varies with aircraft type, equipment availability, and use of brakesDon’t have an accident by helping someone else,it is OK to say ‘No’ to ATC– ‘unable to comply’Photo credit, AirbusContributors to decision errors:The situations were not recognized as ones that should trigger a change of course of action, due to the ambiguity of the cues;Risk was underestimated;Goals conflicted (safety vs. productivity, mission completion or social factors);Consequences were not anticipated or evaluated.A runway should be considered as being contaminated when it is covered with ice, snow, slush, or more than 3 mm of standing water. Attempts to land on contaminated runways involve considerable risk and should be avoided whenever possible. Ideally, if the destination aerodrome is subject to these conditions the departure should be delayed until conditions improve, or an alternate used. Advisory data in the Flight Manual or Operations Manual concerning landing weights and techniques on slippery or contaminated runways should be used to determine whether there is an adequate distance margin over and above the normal Landing Distance Required.Operators should ensure that runways which are promulgated as being ‘slippery when wet’ are annotated as such in their operations manual and that appropriate guidance (such as landing technique, maximum weight, maximum crosswind, minimum headwind) is given to pilots having to land in these conditions.UK CAA AIC 11/ 98Your DecisionScan for situation cuesUse knowledge wiselyAssess risksConsider consequencesTake action, do what is right
28 Decision, a problem of choice Deciding involves a choice, the choice of the safest option; choice involves recall of memory and comparison of facts:Memory can be biased to fit the apparent facts – crosscheck and monitor the situation, especially in a rapidly changing situationFalse memories may be recalled from previous ‘bad habit’ operations or inappropriate procedures from other aircraft types – refer to current SOPsPrevious low consequence decisions can develop into high consequence situations that require revised decisions – continually reassess earlier decisionsComplex situations may indicate a failing course of action – reassess, crosscheck, and intervene if an error is detectedMake timeReduce speed early; 180 kts is approx 3 nm/min (900ft/min), whereas 120 kts is 2 nm/min (600 ft/min)Graphic credit, AirbusDuring a 15 nm final approach, the difference between 180 kt with a late deceleration, and 180 kt to 1000 ft, then decelerating to 120 kt (Vref +10), is only 1 min (5 min vs 6 min). Don’t forget (misjudge) the maximum deceleration rate, allow for tailwinds. In most aircraft the maximum deceleration rate is approximately 3 kts / sec using idle thrust and airbrake. 180kts decelerating to 120kts will take at least 20 sec, approx 1.5 nm; longer in tailwinds
29 Summary Avoiding a landing overrun Identify, avoid, and trap threats and errors.Maintain good situation awareness: airspeed, runway frictionHave a plan, give a briefing: compare the situation with the planKnowledge of ‘no-go’ areas: flooded & contaminated runwaysSpeed above Vref+15, long landings, strong tailwindsFollow SOPs: use approach gates, speed / heightDo not tolerate violations, beware of bad habitsResist peer pressureBrake for safety not for comfortManage the consequences of errorRevise the plan - it is OK to go aroundMake timeHave a safe landing before an ‘on time’ landing‘Errors in Aviation Decision Making: A Factor in Accidents and Incidents’Judith Orasanu, Lynne Martin; NASA-Ames Research Center‘HOW GOOD PILOTS MAKE BAD DECISIONS: A MODEL FOR UNDERSTANDING AND TEACHING FAILURE MANAGEMENT TO PILOTS’Steve Swauger; 12th International Symposium on Aviation Psychology April 14-17, 2003, Dayton, OH
30 “A good landing Captain” Every landingEvery landingA Safe LandingA Safe Landing“A good landing Captain”How heavy is the aircraftHow long is the runwayHow fast is the aircraftHow wet is the runwayHead / Tailwind‘On Speed’Respect the stabilized approach criteriaHeight over the thresholdHow much braking to useis a good example for everyonePhoto credit, AirbusRegulatory references:FAR / JAR Performance informationFAR 121 Subpart I. Airplane Performance Operating LimitationsJAR-OPS1 Subpart G. PerformanceFAA AC Operational landing distances for wet runways; transport category airplanesFAA AC Standard operating procedures for flight deck crewmembersUK CAA Aeronautical Information Circular AIC 61/99 Risks and factors associated with operations on runways affected by snow, slush or waterUK CAA Aeronautical Information Circular AIC 11/98 Landing performance of large transport aeroplanesTransport Canada - commercial and business aviation advisory circular No. 014, Notice to Pilots and Air Operators - Low-Energy Hazards/ Balked Landing/Go-AroundFSF References:Decelerating to stop, Digest Mar 93Dollars and sense of risk management, Digest Dec 94Killers in aviation, Digest Nov 98- Feb 99ALAR Tool Kit, Digest Aug-Nov 2000The Human Factors Implications for Flight Safety Of Recent Developments In the Airline Industry, Digest Mar-Apr 2003LOSA Digest Feb 2005Unaware of strong crosswind – Overrun, Accident Prevention Dec 99Business Jet Overruns, Accident Prevention Dec 99Overrun after cancelled go around, Accident Prevention June 2001MD-80 Overruns runway, Accident Prevention Feb 2002Hurry Up Syndrome, HF Oct 93