RiskAnalysis inSupportofAerodrome Design Rules: Additional Studies Concerning Overrun Accidents Involving SmallerAircraft 

## RiskAnalysis in Support ofAerodrome Design Rules: Additional Studies Concerning Overrun Accidents Involving Smaller Aircraft
1 Introduction

In 2001, AEA Technology completed arisk assessment study on behalf ofthe Norwegian Civil Aviation Authority to support the development ofnational rules for aerodrome physical design that address the requirements identified in ICAO Annex 14. The findings and recommendations arising from that study have led to the development ofproposals for aerodrome physical design by the Norwegian Civil Aviation Authority and these have been subject to review and comment by interested parties during the course ofaconsultation exercise. Comments have been received inresponse to the consultation exercise concerning the validity ofthe overrun risk modelling approach that was used inthe development of recommendations concerning RESA length provisions. Specifically the possibility that the model may not be representative ofthe behaviour of smaller aircraft or ofthe performance ofcommercial carriers (as distinct from general aviation) has been raised. The original studies undertaken by AEA Technology made some initial assessment of the significance ofaircraft size in determining overrun risk and no clear correlation between the two was observed. The modelling approach originally proposed also took some account ofthe better safety performance ofcertain types ofoperation. However, itis recognised that the initial model development did not exhaustively consider all ofthe points that have been raised during the consultation process. To address these concerns some more specific and targeted studies have been undertaken to determine the validity ofthe application ofthe model to the operation of smaller aircraft by commercial carriers.


## 2 

# Model Background

The model for estimating risk isbased on empirical data concerning historical overrun incidents and provides for the quantitative determination of:

• the likelihood ofan overrun accident occurring on either take-off or landing;

• the likely distance travelled inthe event that either atake-off or landing overrun occurs. The modelling approach allows for the use ofdifferent likelihoods ofoccurrence of overruns, according to the nature ofoperations. Different rates ofoccurrence have been 

### EXHIBIT 19December 2003 

# I\

08 AEA TechnologyRisk Analysis in Support ofAerodrome Design Rules: Additional Studies Concerning Overrun Accidents Involving Smaller Aircraft determined for take-off and landing events and, for landing, rates applicable for precision approach and visual/non-precision approach have been identified. Two different models for the likely distance travelled inthe event ofan overrun were developed, the one addressing take-off overruns and the other addressing landing overruns. 

### In assessing the validity ofthe model in describing the types ofoperation ofinterest it will be important to consider these two elements ofthe model, that relate to first the frequency and second the consequence ofan overrun and that together determine the overall risk.


## 3 Revised Analysis
3.1 OVERRUN CONSEQUENCE 3.1.1 Analysis Method For the purposes ofthe model, the consequence element ofrisk is determined according to the distance beyond the runway end that an aircraft travels inthe event ofan overrun. 

### In order to test the validity ofthis element ofthe model, selected data sets corresponding with smaller aircraft and those operated by commercial carriers only were analysed inthe manner employed during the original model development process. 

### Inthe first instance, two data subsets comprising all aircraft with amaximum certified gross weight ofless than 30 tonnes were compiled separately for the available take-off and landing overrun data. The largest aircraft within these selected data sets was found tobe the HS 748, with aweight of46500 lbs, equivalent to 21.1 tonnes. Further selected data sets were then compiled that comprised operations by commercial carriers only. The majority ofthese were identified within the available data set as undertaken in accordance with FAR Part 135. A much smaller number were undertaken in accordance with FAR Part 121. For the non-US operations (from Canada and the United Kingdom) data were included inthe commercial carrier data sub-set where operations were identified as passenger, scheduled passenger, non-scheduled passenger, freight, scheduled freight ornon-scheduled freight. All data relating to general aviation, most ofwhich was subject to FAR Part 91 rules and representing amixture ofbusiness, corporate, personal, positioning, maintenance and training flights was thus removed. A selected data set comprising turboprop aircraft only was also compiled for landing and take-off overruns. The data sets were then analysed by plotting cumulative probability distribution functions describing the probability oftravel to agiven distance orbeyond and exponential fits to the observed distribution functions were determined. The results obtained for the various sub-sets ofdata were then compared to determine whether any significant differences could be identified between them. The forms ofthe distributions

AEA Technology 2 19 December 2003Risk Analysis in Support of Aerodrome Design Rules: Additional Studies Concerning Overrun Accidents Involving Smaller Aircraft functions derived from the empirical data were reviewed to determine the quality ofthe fit and extent to which they might provide areliable basis for the prediction ofthe expected behaviour. Finally, the available narrative describing the event sequences to which the identified data relate was reviewed to determine whether there may be anyjustification for excluding any data points. For take-off overruns, an outlying point relating to atake-off from the wrong runway was eliminated on the basis that this would not be representative ofthe Norwegian cases ofinterest. There may be somejustification also for eliminating asecond outlying point relating to an incident in which an aircraft became airborne before developing aproblem and returning to the runway. Such an incident may be regarded as not being an overrun and hence may be considered to be beyond the scope ofincidents that the RESA provision can be expected to accommodate. 3.1.2 Landing Overrun Analysis Results The data sub-sets compiled for landing overrun are summarised in Appendix 1and the data ispresented graphically inAppendix 2. The available data set includes 67 landing overruns involving smaller aircraft «21.2 tonnes) and 22 ofthese cases involved commercial carriers, the majority ofwhich were subject to FAR Part 135 Rules and were dual pilot operated flights. The different data sets give generally similar results that are consistent with the value originally proposed for the distribution function based on the complete data set, including events that involved larger aircraft in excess of 30 tonnes. There is an indication that landing overruns involving turboprop aircraft result in generally slightly shorter overrun distances than is found for smaller jet and turboprop aircraft as awhole but, due to the presence oftwo outlying points that have a significant influence on the exponential function, this is not reflected in the modelled cumulative probability distribution function. Similarly, landing overruns involving commercial carriers appear to result in slightly shorter overrun distances than is found for smaller aircraft as a whole. There is one significantly outlying point within the commercial carrier data set, with an overrun distance of478 m and review ofthe available narrative reveals that this relates to unusual circumstances. The incident involved apower offforced landing with atouchdown well beyond the threshold. On that basis itmight be argued that itis unrealistic to expect standard RESA provisions to protect against this type ofextreme incident and afurther refined data sub-set with this data point removed has also been analysed. The distribution functions determined for the various data sub-sets are summarised below:

• Original distribution function "best estimate" (all data): M(x) = exp (-0.0081 x)

• Original distribution function "lower bound" (all data): N, (x) =exp (-0.0101 x)

• New small aircraft distribution function: M(x) = exp (-0.0075 x)

• Small turboprop only distribution function: N,(x) = exp (-0.0072 x)

• Small aircraft, commercial carrier distribution function: 

### M(x) = exp (-.00079 x)

ABA Technology 3 19 December 2003RiskAnalysis inSupportofAerodrome Design Rules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft

• Small aircraft, commercial carrier, extreme outlying point removed distribution function: N/(x) =exp (-0.0103 x) Itmay be noted that, when using an exponential function ofthe form exp (-ax) to represent adistribution function, the larger the coefficient athe quicker the function falls offwith distance. The last function, derived from the small aircraft and commercial carrier data set with the outlying point removed is seen to give the most rapid fall offwith distance but isnot seen tobe very greatly different from the distribution functions originally proposed on the basis ofthe full data set. This data provides afunction that is very close to the "lower bound" function used inthe original assessment. Review ofthe data and the extent to it correlates with the exponential distribution functions indicates that the functions that have been determined provide asensible basis for modelling inthe area ofprimary interest, i.e. up to ofthe order of300 metres from the runway end. The log plot for the small aircraft and commercial carrier data set with the outlying point removed gives good linearity throughout the range and there is no indication that the function truncates rapidly before 300 metres: itis concluded that the function should give areasonably reliable basis for extrapolation beyond the immediate limit ofthe empirical data set. The data set is found to include anumber ofpoints inthe region ofmore particular interest inthe current context: i.e. inthe range at orbeyond the 150m limit ofthe ICAO standard distance ofrunway end strip plus RESA for aCode 3 &4 instrument runway. Six out of22points (27%) are found to lie inthis region, the furthest being an overrun of260 metres (with 2points ofthese located at 152metres) and the empirical data therefore demonstrates that anon-trivial proportion of smaller aircraft operated by commercial carriers can be expected to travel adistance of 150 metres or more during a landing overrun. The best fit exponential distribution function indicates 21.3% of landing overruns travelling to this distance ormore. The original model predicts a slightly higher proportion of29.7% oflanding overruns travelling to 150metres or more. 

### 3.1.3 Take-off Overrun Analysis Results The data sub-sets compiled for take-off overrun are summarised in Appendix 3 and the data ispresented graphically in Appendix 4. The available data set includes 21 take-off overruns involving smaller aircraft «21.2 tonnes) and 10ofthese cases involved commercial carriers, the majority ofwhich were subject to FAR Part 135 Rules. As was found for the landing overruns, the different subsets ofdata exhibit comparable distributions and are generally consistent with the model previously proposed on the basis ofthe complete data set including larger aircraft. Again, having regard to the available narrative, adata sub-set excluding the most extreme point was analysed, this point corresponding with an incident in which an aircraft became airborne before developing aproblem and returning to the runway. The distribution functions determined for the various data sub-sets are summarised below:

• Original distribution function "best estimate" (all data): Nt (x) =exp (-0.0058 x)

AEA Technology 4 19December 2003Risk Analysis in Support ofAerodrome Design Rules: Additional Studies Concerning Overrun Accidents Involving Smaller Aircraft

• New small aircraft distribution function: Nt (x) = exp (-0.0051 x)

• Small turboprop only distribution function: Nt (x) = exp (-0.0042 x)

• Small aircraft, commercial carrier distribution function: N,(x) = exp (-0.0039 x)

• Small aircraft, commercial carrier, extreme outlying point removed distribution function: N,(x)

### = exp (-.00051 x) The starting data set is somewhat smaller for take-off overruns than landing overruns, take-off overruns being generally less frequent events. The selected data sub-sets are therefore somewhat small and the cumulative probability functions derived from them are correspondingly subject to some statistical uncertainty. Itmay be noted that the distribution function derived from the small aircraft and commercial carrier data sub-set indicates agenerally higher probability ofoverrun to greater distances than the function derived previously on the basis ofall data including larger aircraft. Four out of9points (44.4%) in the data set for small aircraft operated by commercial carriers with the extreme outlying point removed are found to liebeyond 150m and the empirical data therefore demonstrates that anon-trivial proportion of smaller aircraft operated by commercial carriers can be expected to travel adistance of 150metres ormore during a take-off overrun. The original model based on the full data set indicated 41.9% oftakeoffoverruns travelling to this distance ormore and the new model based on smaller aircraft operated by commercial carriers indicates aslightly higher proportion of46.5% travelling to this distance. 

### 3.1.4 Conclusions Our overall conclusion is that the model developed forpredicting the distance travelled inthe event ofeither atake-off oralanding overrun using the complete data set that included larger as well as smaller aircraft provides agenerally good representation of the behaviour of smaller aircraft «21.2 tonnes) operated by commercial carriers. Similar behaviour, within the general limits ofthe statistical uncertainty ofthe data sets, was observed whichever way the data was divided. That is to say that, as far as the distance travelled during an overrun is concerned, smaller and larger aircraft exhibit similar behaviour, turboprop andjet aircraft exhibit similar behaviour and aircraft operated by commercial carriers and general aviation exhibit similar behaviour. In the case oflanding overruns, anew model, based on smaller aircraft data alone predicts slighter shorter overrun distances whereas inthe case oftake-off overruns such amodel predicts slighter longer overrun distances. The models based on the restricted data sets, inparticular that for take-off, are subject to some uncertainty due to the limited number ofdata points available and the observed differences in the predictions ofthe various models may not be significant. 

### 3.2 OVERRUN FREQUENCY The original analysis ofoverrun frequency undertaken by AEA Technology specifically sought to derive avalue that is appropriate to commercial carriers. Specific data on the numbers ofoverruns and movements for commercial carriers from which to derive an overrun rate for commercial carriers was not readily available but data on the rate of overruns for commercial carriers involving atotal loss ofthe aircraft was available.

AEA Technology 5 19December 2003RiskAnalysis inSupport ofAerodrome DesignRules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft Using information on the proportion ofoverruns that result in atotal loss, an overrun rate for commercial aircraft was derived. The value obtained should therefore not be influenced by ahigh rate ofoverruns for general aviation. The basic accident rate that served as the basis for the model was based on "first world operations". It specifically excluded all business jet aircraft and identified rates for turboprop aircraft and largerjet aircraft separately, thereby ensuring that any higher rate ofaccident in certain types of operation (e.g. commuter /air taxi operations in the US that are undertaken in accordance with FAR Part 135requirements rather than the more stringent FAR Part 121 requirements) not applicable to the current case could be accounted for, assuming that the observed largejet accident rate is generally representative ofthe highest standard ofoperation. Consideration was given to the dependence ofoverrun rate during landing on the availability ofprecision approach landing aids. Available data indicates that the precision approach landing overrun rate is significantly lower than the rate encountered during non-precision and visual approach operations. The "best estimate" overrun rates determined in the previous studies are as follows:

• Take-off overrun rate: 0.33 per million movement movements;
• Average landing overrun rate: 1per million movements;
• Precision approach overrun rate: 0.6 per million movements;
• Non-precision/visual approach overrun rate: 4.68 per million movements. Some uncertainty inthe method for determining these rates was noted in the original report and "lower bound" rates that are half the above values were also proposed. A further factor investigated inthe previous study was the dependence ofoverrun rate on the amount ofrunway available in excess ofthe identified landing distance required for the operation concerned. The analysis performed indicated that the overrun rate where no excess runway is available is ofthe order often times higher than the average rates indicated above. Where the amount ofexcess runway ismore than the order of 750 m, the overrun rate is found to be very much lower than the above average values. Itmay be noted that half ofthe identified smaller aircraft take-off overrun incidents involved non-commercial carrier (general aviation) operations and two thirds ofthe smaller aircraft landing overrun incidents involved non-commercial carriers. These are, however, very much the minority ofincidents as awhole. General aviation accounted for 36 out of 118 landing incidents for which overrun distances are available and for 7 out of39 take-off incidents for which overrun distances are available. On that basis it may be concluded that, even ifthe attempts to exclude non-commercial carrier overruns from the data upon which the incident frequencies were based were not to have been successful the impact on the estimated commercial carrier rate would be limited (less than a 30% overestimate ofthe landing overrun rate and less than a20% overestimate of the take-off overrun rate). The same general argument applies to the possible influence ofhigher rates ofcertain types ofcommercial carrier operation (e.g air taxi /commuter operations). The numbers ofoverruns within the database relating to different types ofnon-general aviation operations is summarised below in Tables 1 &2, for take-off and landing operations respectively.

AEATechnology 6 19December 2003RiskAnalysis inSupportofAerodrome Design Rules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft Table 1: Take-off Overrun: Categories ofNon-GA Operations Type ofOperation Number ofIncidents Part 121 16 Part 129 1 Part 135 8 Other /Non-US 6
Table 2: Landing Overrun: Categories ofNon-GA Operations Type ofOperation Number ofIncidents Part 121 24 Part 129 2 Part 135 16 Other /Non-US 22 The largest single contribution to the total number ofincidents ismade by Part 121 operations and these comprise the majority ofUS operations. (A significant contribution to the total is made by non-US operations (UK, Canada, Australia) and these operations cannot be split in accordance with US operating rules.) Itis to be emphasised that the incident rate employed inthe risk assessment isbased on the historical accident rates determined for different aircraft types (commercial jets, turboprop and executive jets). The majority ofthe Part 135 accidents are found to relate to executive jet operations and will therefore not have been counted inthe estimation of incident rates. On that basis itis concluded that any higher rate ofincidents for certain types ofPart 135 operations will have anegligible impact on the overall incident rates employed inthe modelling exercise. The possible influence of such ahigher rate can be accommodated by use ofa "lower bound" value for the incident rate when determining the overall risk, as described inthe following section. 

### 3.3 REVISED RISK ESTIMATION Using the modelling approach used previously, risk estimates have again been derived for various lengths ofrunway end strip and RESA. On the basis ofthe foregoing analysis, we identify the following model parameters as the most optimistic values that might bejustified:

• Take-off overrun "lower bound": 0.167 per million movements;
• Landing overrun "lower bound" precision: 0.3 per million movements;
• Take-off overrun distance, original "lower bound" function: N, (x)

### = exp (-0.0065 x)

• Landing overrun, revised smaller aircraft function: N, (x) =exp (-0.0103 x) Risk estimates based on these values for various runway end strip and RESA distances have been calculated and are presented below in Table 3. The total risk mitigation benefit associated with RESA provision also includes an element associated with undershoot and this is included inthe data in the table.

AEA Technology 7 19December 2003RiskAnalysis inSupportofAerodrome Design Rules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft Table 3 Residual Risk Estimates according to RESA/strip length Distance/m Overrun Risk

Take-off Landing Mean Undershoot Total risk 10 0.15649 0.270638 0.213564 b.125782 0.276455 20 0.146642 0.24415 0.195396 0.107921 0.249356 30 0.137413 0.220254 0.178834 0.095382 0.226525 40 0.128766 0.198697 0.163731 0.085661 0.206562 50 0.120662 0.17925 0.149956 0.077744 0.188828 60 0.113068 0.161706 0.137387 0.0711 0.172938 70 0.105953 0.14588 0.125916 0.065409 0.158621 80 0.099285 0.131602 0.115443 0.060458 0.145672 90 0.093037 0.118722 0.105879 0.056101 0.13393 100 0.087182 0.107102 0.097142 0.052231 0.123257 110 0.081695 0.09662 0.089157 0.048767 0.113541 120 0.076554 0.087163 0.081859 0.045647 0.104682 130 0.071736 0.078632 0.075184 0.042821 0.096594 140 0.067222 0.070936 0.069079 0.040249 0.089203 150 0.062991 0.063994 0.063492 0.037898 0.082442 160 0.059027 0.05773 0.058379 0.035743 0.07625 170 0.055312 0.05208 0.053696 0.03376 0.070576 180 0.051831 0.046983 0.049407 0.03193 0.065372 190 0.048569 0.042384 0.045477 0.030237 0.060595 200 0.045513 0.038236 0.041875 0.028666 0.056208 210 0.042649 0.034494 0.038571 0.027207 0.052175 220 0.039965 0.031118 0.035541 0.025848 0.048465 230 0.03745 0.028072 0.032761 0.024579 0.045051 240 0.035093 0.025325 0.030209 0.023394 0.041906 250 0.032884 0.022846 0.027865 0.022284 0.039007 260 0.030815 0.02061 0.025712 0.021244 0.036334 270 0.028876 0.018593 0.023734 0.020267 0.033868 280 0.027058 0.016773 0.021916 0.019349 0.03159 290 0.025355 0.015132 0.020244 0.018485 0.029486 300 0.02376 0.013651 0.018705 0.01767 0.02754 We conclude that, on the basis ofthe most optimistic assumptions concerning overrun rates and distributions, aRESA extending to 300 m from the runway end (the ICAO recommendation for aCode 3 &4 runway and aCode 1 &2 instrument runway ofa 60m strip plus 240 m RESA) provides risk mitigation atthe TLS level of 10'8per movement that has been identified as abasic target to be achieved where practicable. A RESA extending to 150m from the runway end (the ICAO standard for aCode 3 &4 runway and aCode 1 &2 instrument runway ofa 60m strip ..plUS 90 m RESA) provides risk mitigation to the "benchmark" quantitative target of 10' per movement that represents the identified normal minimum recommended risk limit.

AEA Technology 8 19December 2003Risk Analysis in Support of Aerodrome Design Rules: Additional Studies Concerning Overrun Accidents Involving Smaller Aircraft The strip lengths of 30 m and 60 m, representing the ICAO standards for Code I and Code 2 non-instrument runways, are identified as insufficient to meet the 10-7 per movement risk level.


## 4 Other Issues

In addition to the comments concerning the general validity ofthe risk model that have been considered inthe previous section, anumber of specific questions have been raised that merit comment, as set out below. 4.1.1 Runway Length Of 104 landing overruns where the runway length is identified 7 took place at Code 1 runways (:s 800 metres) and 10took place at Code 2runways (> 800 m and

## s 1200 m). A further 40 took place on Code 3runways but 12ofthese are found to have occurred at relatively short Code 3 runways (:s 1400 m). The remaining 47 took place at Code 4 runways (> 1800 m), the longest ofwhich was 3382 metres inlength. Six ofthe 7 Code 1incidents involved commercial carriers, 5 ofthe 10Code 2 incidents involved commercial carriers and 5 ofthe 12incidents on shorter Code 3runways involved commercial carriers. For take-off overruns, ofthe 39 incidents for which runway length information is available, no incidents took place on Code 1runways, 4 took place on Code 2runways, 7 took place on Code 3runways and the remaining 28 incidents took place at Code 4 runways, the longest ofwhich was 4442 metres. Ofthese incidents, 2 Code 2runway events involved commercial carriers and 4 Code 3 runway events involved commercial carriers. Itmay be concluded on the basis ofthis information that a significant number of overrun incidents do take place at shorter runways and that a significant fraction of these involve commercial carriers. In the absence of specific information onthe number ofmovements that took place at runways ofidentified length itisnot possible to make any specific conclusions concerning the relative rates per movement ofoverruns at shorter or longer runways. As was determined inthe original analysis, there is clear evidence that the overrun rate is dependent on the amount ofrunway available in excess ofthe identified landing distance required for the operation concerned. This basic conclusion is expected to apply to larger and smaller aircraft alike. A certain proportion ofoperations of smaller aircraft can be expected to take place atrelatively long runways. For example, hub and spoke type operations between larger and smaller airports involving smaller aircraft would be expected to involve at least lout ofevery two movements at arelatively long runway. In addition, point-to-point operations for certain routes between two larger airports where there is limited demand may involve smaller aircraft movements at long runways only. On that basis itwould be expected that the historical rate ofoverruns for

AEA Technology 9 19 December 2003Risk Analysis in Support ofAerodrome Design Rules: Additional Studies Concerning Overrun Accidents Involving SmalIer Aircraft smaller aircraft may be less than that for larger aircraft. However inthe absence ofthe relevant data itisnot possible tomake any further sensible comment on this issue. 4.1.2 Approach Aid Availability As has been discussed briefly above, previous analysis has indicated that historical incident rates are significantly lower for operations where precision approach aids are available. Inresponse to a specific request, we provide the following specific information concerning the proportion ofincidents within the available data setwhere different approach aids (lLS, VASI, PAPI) were available for different categories of operation (General Aviation, Passenger and Freight). This data ispresented inthe following tables. Table 4: ILS Glide path Operations Flight Aircraft Size category Total Small Large Total 36 10 26 GA 9 7 2 Passenger 25 2 23 Freight 4 2 2 Table 5: Visual with VASI glide path Flight Aircraft Size category Total Small Large Total 10 9 1 GA 6 6 0 Passenger 2 0 2 Freight 3 3 0 Table 6: Visual with PAPI glide path Flight Aircraft Size category Total Small Large Total 6 4 2 GA 2 2 0 Passenger 4 

### 1 3 Freight 

### 1 1 0 Table 7: Visual/no glide path indicator Flight Aircraft Size category Total Small Large Total 6 6 0 GA 2 2 0 Passenger 1 1 0 Freight 3 3 0

AEA Technology 10 19December 2003RiskAnalysis inSupport ofAerodrome DesignRules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft Table 8: No information provided Flight Aircraft Size category Total Small Large Total 77 54 23 GA 34 32 2 Passenger 34 15 19 Freight 9* 7 1 *no aircraft type identified for one incident Again, inthe absence ofspecific information concerning the number ofmovements within each ofthe above types ofoperation itis not possible to draw any firm conclusions concerning relative incident rates. A significant proportion ofincidents take place where ILS glide path indication is available and the majority ofthese involve larger aircraft. The relative proportion ofincidents involving larger and smaller aircraft is generally consistent with the relative numbers ofthe two types ofaircraft in the international fleet and their relative numbers ofmovements. A larger proportion ofincidents where VASI and PAPI glide path indication isprovided to visual approaches involve smaller aircraft. This would be generally consistent with the expectation that more movements ofsmaller aircraft take place at smaller airports with limited facilities. All the events where no glide path indication is identified involved smaller aircraft, in line with the above comments. For those cases where no information isprovided, the majority involved smaller aircraft. We may speculate that a good proportion ofthese incidents took place at airports with relatively limited approach aid facilities. In total, 83 incidents involved smaller aircraft and 52 involved large aircraft. The higher number ofincidents involving smaller aircraft, for which we would expect a slightly lower number ofmovements, indicates ahigher rate ofincidents for smaller aircraft. This observation would be consistent with ahigher rate ofincidents for general aviation and, to some extent, US air taxi and commuter operations.


## 5 Overall Conclusions

On the basis ofthe above analysis we would reaffirm the conclusions and recommendations presented inthe earlier report concerning RESA and runway end strip lengths:

• Combined length ofrunway end strip and RESA not less than the current ICAO Annex 14standard of 150m in any runway case (basic requirement to meet aTLS of 10-7per movement for average risk movements);

• Combined length ofrunway end strip and RESA preferably approaching the current ICAO Annex 14recommendation of300 m inrelation to take-off and landing overrun risk mitigation (objective to achieve aTLS of 10-8per average movement where practicable and aTLS of 10-7per movement forhigher risk movements);

AEATechnology 11 19December 2003RiskAnalysis inSupportofAerodrome DesignRules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft Following re-examination ofthe available data inthe light ofthe points raised, we see no grounds inrelation to the specific characteristics of smaller aircraft operations, operations at shorter runways or characteristics ofcommercial carrier operations not previously taken into account in our original analysis that would change our earlier conclusions. The historical accident record supports the conclusion that overrun accidents are a significant contributor to the overall rate ofserious accidents involving fatalities and total hull loss and that RESA provision, in accordance with the above recommendations, should help toreduce the risk associated with such events. Whichever way the available data on overrun distance is sub-divided, according to the type ofoperation, comparable cumulative probability distributions are found. Smaller and larger aircraft exhibit similar behaviour, turboprop andjet aircraft exhibit similar behaviour and smaller aircraft operated by commercial carriers and general aviation exhibit similar behaviour. On that basis we conclude that the available cumulative distribution functions are generally representative ofthe operations ofinterest. As far as the overrun incident rate element ofthe model is concerned, specific attention was taken during the initial development ofthe model to identify arate that was appropriate for the types ofcommercial operations ofinterest and to ensure that this was not an over-estimate due to the inclusion ofnon-representative higher risk operations in the data set from which the rate was derived.

AEATechnology 12 19December 2003RiskAnalysis inSupportofAerodrome DesignRules:

Additional Studies Concerning Overrun Accidents Involving SmallerAircraft Appendix 1: Commercial Carrier Operated Smaller Aircraft Landing Overrun Dataset
Date x/m Aircraft Engine type Type of Operation Operator Instrument / Glide Slope Indicator 01/08/81 53DHC-6 Turboprop Canadian Passenger N/A 01/10/82 3HS 748 Turboprop UK Passenger N/A 15/06/83 30Grumman Gulfstream G1159 Turboprop Part 135 Scheduled freight Orion Air Inc. visual - noglide path indicator 10/09/83 76 Beechcraft B-90 Turboprop Part 135 Non-scheduled passenger Mayo Aviation Incorporated visual - no glide path indicator 29/11/83 40 HS 748 Turboprop UK Scheduled passenger visual with PAPI 06/07/84 9HS 748 Turboprop Canadian Passenger Quebecair N/A 15/12/84 152Cessna CE-500 Citation Turbofan Canadian Non-scheduled passenger Austin Airways Ltd. N/A 31/01/85 116Fairchild SA-227 Turboprop Part 135 Scheduled freight Sat -Air Inc. RNAV/ visual, VASI glide path indication 17/11/88 60 Gates Learjet Turbofan Part 135 Non-scheduled passenger Pacific Flight, Inc. visual - no glide path indicator 15/02/89 61 Falcon 20 Turbofan Part 135 Non Scheduled freight Reliant Airlines Inc. ILS-complete and VASI 06/06/90 478 CE 208 Turboprop Part 135 Scheduled freight West Air Industries visual - no glide path indicator 02/07/91 168Gates Learjet Turbofan Part 135 Non Scheduled freight Connie Kalitta Services Inc. visual with VASI glide slope indication 06/10/92 6 Fairchild SA-227 Turboprop Part 135 Scheduled passenger Northeast Express Regional airlines Inc. ILS-complete, including glide path 22/11/92 61 Gates Learjet Turbofan Part 135 Non-scheduled passenger Flight operations Inc. ILS-complete, including glide path indication 29/04/93 209 EMB-120 Turboprop Part 135 Scheduled passenger Continental Express, Inc. N/A 21/07/93 46Convair 580 Turboprop Canadian Non-scheduled passenger Canair visual - noglide path indicator 26/01/96 85 Falcon 20 Turbofan Part 135 Non Scheduled freight Yip Group Inc. N/A 13/08/96 96 Gates Learjet Turbofan UK Non-scheduled passenger MAC Aviation Sociedad Anonima PAR 19/08/97 260 Fairchild SA-226 Turbofan Part 135 Non Scheduled freight Superior Aviation Inc. ILS-Iocaliser only, VASI glide path indication 18/02/98 72 Falcon Turbofan Canadian freight Reliant Airlines Inc. NDB and PAPI glide slope indication 23/05/98 152Gates Learjet Turbofan Part 135 Non-scheduled passenger Panther Aviation visual - ILS-Iocaliser only 06/08/98 137HS 748 Turboprop Canadian freight Wasaya Airways Ltd. visual

AEA Technology 13 19December 2003RiskAnalysis inSupportofAerodrome DesignRules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft Appendix 2: Graphs ofLanding Overrun Distributions for Smaller Aircraft Figure A2.1 Plot ofall data for smaller aircraft landing overruns and best exponential fit

• All Data

• Turbo prop only Commercial Carriers only --Expon. (All Data)
y = e-O.007SX
200 

### o 400 600

Figure A2.2 Plot ofturboprop data and best exponential fit

AEATechnology 14 19December 2003RiskAnalysis inSupportofAerodrome Design Rules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft Figure A2.3 Plot ofCommercial Carrier only data and best exponential fit

1.2 y

## = e-G·0079X R2 = 0.9297 1 

### 0.8 0.6 0.4 0.2 

## o 

# o 100 500 600

200 300 

### 400

Figure A2.4 Logarithmic Plot of Commercial Carrier only data and line ofbest fit

0.1

0.01

## o 100 200 300 400 500 600

AEA Technology 15 19December 2003RiskAnalysis inSupportofAerodrome DesignRules: Additional Studies Concerning Overrun Accidents Involving SmallerAircraft Figure A2.5 Plot ofCommercial Carrier only data with outlying point removed and best exponential fit
1.2 1



### 0.6 y

# = e-O.0103x I R2

# = 0.9441 0.4 

### 0.2


## o 100 

### 300 200

Figure A2.6 Logarithmic Plot ofCommercial Carrier only data with outlying point removed and line ofbest fit

0.1

0.01

## o 150 300 200 250 50 100

AEATechnology 16 19December 2003RiskAnalysis inSupportofAerodrome DesignRules:

Additional Studies Concerning OverrunAccidents Involving SmallerAircraft Appendix 3: Commercial Carrier Operated Smaller Aircraft Take-off Overrun Dataset

Date 28/07/1984 13/08/1985 26/05/1987 16/08/1988 15/04/1992 12/05/1994 13/07/1994 16/08/1996 29/11/1997 28/08/1998

AEA Technology

x/m Aircraft Engine type Type of Operation Operator 35Gates Learjet Turbofan Part 135 Non-scheduled passenger Panarama Flight Service Incorporated 274Gates Learjet Turbofan Part 135 Scheduled freight Konnie Kalitta Services 355BAeJ-3101 Jetstream Turboprop Part 135 Scheduled passenger Air New Orleans 255 Fairchild SA-226 Turboprop Part 135 Scheduled passenger BrittAirways 

## oFokker F28 Turbofan Part 121 Scheduled passenger USAir 63Saab SF-340B Turboprop Part 121 Scheduled passenger Wings west airlines 136Gates Learjet Turbofan Part 135 Non-scheduled passenger Mid-Atlantic Jet Carrier 250HS748 Turboprop UK Freight Emerald 61 Beech 1900 Turboprop Canadian Scheduled Passenger Ministic 613Falcon 20 Turbofan Part 135 Non Scheduled freight ReliantAirlines

17 19December 2003RiskAnalysis inSupportofAerodrome Design Rules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft Appendix 4: Graphs ofTake-off Overrun Distributions for Smaller Aircraft Figure A4.1 Plot ofall smaller aircraft take-off overrun data and best exponential fit

1.2

y = e-O.OO51X R2 = 0.9632

---- - 1

y = e-O.0042X R2 = 0.8639

400 0.8 • Commercial carriers Turboprop only -Expon. (All data)

AEA Technology 18 0.6 0.4 0.2 

### o 

## o 200 400 600 800

Figure A4.2 Plot ofturboprop data and best exponential fit



### o 50 100 150 200 250 300 350

19December 2003RiskAnalysis inSupportofAerodrome DesignRules: Additional Studies Concerning OverrunAccidents Involving SmallerAircraft 5.1.1 Figure A4.3 Plot of Commercial Carrier only data and best exponential 

### fit
1.2

0.4 y

## = e-O.0039x R2 = 0.9638 0.8 0.6

0.2 

### o o 200 700 300 400 100 500 600

Figure A4.4 Logarithmic Plot ofCommercial Carrier only data and best line of 

### fit

0.1 y = e-O.0039x R2 = 0.9638

0.01

## o 100 500

200 300 400 600 700

AEA Technology 19 19December 2003Risk Analysis in Support ofAerodrome Design Rules: Additional Studies Concerning Overrun Accidents Involving Smaller Aircraft Figure A4.5 Plot of Commercial Carrier only data with outlying point removed and best exponential fit

1.2

400 0.8 0.6 0.4 0.2 

## o o 100 150 200 250 300 350

Figure A4.6 Logarithmic Plot ofCommercial Carrier only data with outlying point removed and line ofbest fit

50

0.1 400 

## o 50 200 350 250 300 100 150

AEA Technology 

### 20 19December 2003