Lightning-Warning Systems for Use by Airports (2008)

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34 Introduction The objective of this research project was to review current lightning detection and monitoring technology and airport ramp operating procedures, and then use that information to identify areas for possible improvements in efficiency and in enhanced safety. Lightning monitoring systems were reviewed in Chapter 1. The results of a survey of airport and airline ramp procedures for nearby cloud-to-ground lightning events and of the lightning technology employed were summarized in Chapter 2. The objective of Chapter 3 is to perform a cost analysis, in- cluding both the direct and indirect operational costs resulting from the closure of ramps and aprons and the financial and operational impacts to the National Airspace System. The analytical process examines the incremental cost savings that could be expected from modified or enhanced lightning detec- tion and warning systems or from improved operating proce- dures. The implications of the ripple effects of aircraft arriving late at destinations are incorporated into the analysis. Airport Operations During Lightning Events Cloud-to-ground lightning strokes present a clear and immediate danger for ground personnel involved in outdoor ramp operations, such as aircraft fueling, baggage handling, food service, tug operations, and guiding and directing aircraft to their assigned gates. When this danger presents, airport ramp operations are suspended until the danger has passed. Decisions about ground personnel and ramp operations are made by the airports and airlines, not by the FAA. Indi- vidual airlines, companies providing airport workers, and airport management often have very different procedures and standards for identifying and responding to potential lightning hazards, as was documented in Chapter 2. Because airlines and airports do not report suspensions of ramp operations to the FAA, there is little hard data available on actual suspensions of ramp operations. Short-term sus- pension of airport ramp operations does not generally close the airport or cause en route delays or ground holds of traffic destined for the affected airport. If ramp operations are sus- pended for a long time, however, all the available ramp space may become occupied, leaving no space to handle incoming new arrivals. In this case, the airport manager may have to take the rare action to close the airport and report the closure to the FAA. It should be noted that such closures are not a di- rect response to the lightning hazard, but rather a response to not having the ramp capacity to accept new arrivals. Except for busy airports with limited ramp space, we would suspect that this is uncommon, although we have no firm data to sup- port this conclusion. While the suspension of ramp operations does not directly or immediately affect flight operations, planes scheduled for departure will not be able to load or leave their gates. Al- though arriving planes may be able to taxi to their arrival gates (if the gates are not already occupied), baggage typically will not be able to be unloaded. After all the gates are occu- pied, newly arriving aircraft will have to park elsewhere on the airport. Specific Impacts and Costs of Suspending Ramp Operations Ramp operating procedures vary from airline to airline. In general, however, ramp closures mean • No new passenger enplaning or deplaning, • No new loading or unloading of baggage, • The baggage already loaded onto carts stays put, • No servicing of aircraft (fuel, food service, etc.), • Passengers and flight crew remain on the aircraft (or stay in the terminals waiting to board), C H A P T E R 3 Cost Analysis

• Aircraft not already connected to a generator or ground power unit keep their engines running (at least minimally) to maintain cabin and instrument power, and • Available gates fill up and additional arrivals park elsewhere. Many of the costs could be classified as “wasted time.” While we considered it appropriate to consider such wasted time as a cost, it is important to distinguish between “lost opportunity” time (time that could have been spent doing something else), delay or annoyance time (passengers not being able to get to their next destination, or crew not being able to move to their next flight assignment), and direct costs, such as fuel costs for idling engines, which entail real dollars that have to be paid by the person or entity incurring the cost. While it is reasonable to include some effective hourly “cost” associated with passenger delay time, nobody really pays the delayed passengers cash (or even provides flight coupons). Flight crews may well waste some time during a ramp closure, but to the extent they are salaried or paid by flight time (and not total time), ramp delays do not necessarily involve a true cost to the airline unless flight personnel reach their daily or weekly service limits. Baggage handlers may well be idle during a ramp closure, but unless they get so far behind that they have to work overtime, they may be able to get caught up during their normal scheduled work hours at no extra cost to the airline. Unexpected or unscheduled overtime, on the other hand, could represent a very significant “real” cost. It would seem that flight delays would always entail some very significant real costs, but the analysis of the costs is not straightforward. Passengers and crew making intraline con- nections at the affected airport should still be able to make their next flights, since all loading and unloading at the air- port for that airline is suspended across the board. Flights (or passengers, or crew) making interline connections to their destination airports, on the other hand, could miss connections, resulting in required rescheduling or rebooking of flights, under-capacity flights, possible special movements of aircraft, and flight personnel shifted to cover for delayed airline employees. Furthermore, depending on contract terms, air- line crews who experience extended wait periods as a result of lightning (or other weather) delays may become restricted in their ability to maintain their flight schedules. Reserve crews may be available at base airports, which would minimize the impact on flight operations. At other airports, flights may need to be canceled to allow the crews the requisite daily rest period. This could result in impacts on flight schedules and produce a real cost to the airline. Table 1 presents a summary of potential costs incurred by events of varying duration. With the exception of the possible total closure of an air- port because of the lack of ramp capacity to accept landing aircraft, lightning-based ramp closures should not result in FAA-imposed en route delays or ground holds. There may be some exceptions, but most downstream impacts from ramp closures will be due to delayed aircraft departures by the affected airline, resulting in some missed connections to desti- nation airports (because many passengers will not be connect- ing at the destination airport, they won’t miss any connections, even though they arrive late). These delays would be similar to simple mechanical delays that can affect individual flights. Perhaps the largest of such impacts might be from aircraft not reaching their final scheduled destination of the day, which would mean that the airline’s aircraft will not be positioned for the next day’s flights. Approach to Cost Savings Analysis There are many possible ways to address this sort of analy- sis. Initially, we examined the use of a “queue” delay reduction approach or a “linear” delay reduction approach, as de- scribed in Delay Causality and Reduction at the New York City 35 Cost Item Short Duration Delay Medium Duration Delay Long Duration Delay Passenger Time Yes Yes Yes Direct Cost to Airline Minimal Some Likely Ripple Effect Some Some Likely En Route Delay None Unlikely Possible Notes: Short duration is defined as less than or equal to 60 min. Medium duration is defined as greater than 60 min and less than or equal to 135 min. Long duration is defined as greater than 135 min. Table 1. Cost effects for delays of various duration.

Airports Using Terminal Weather Information Systems (26). An analysis of that study found that this approach is more appropriate for evaluating the impact of thunderstorms along the flight path, rather than the effect of cloud-to- ground lightning strikes in the vicinity of the airport on ramp operations. The key issues are the tradeoffs between safety (close ramps as needed to prevent injuries or deaths from lightning) and efficiency (minimize ramp closures). Safety is clearly the driv- ing factor in airport and airline investment in lightning de- tection and warning systems, but it is difficult to quantify since there are so few reported deaths and injuries caused by lightning. Because our survey did not identify any specific concerns about missed warnings or unsafe working condi- tions, we concluded that the basic safety requirements are well met by the current systems and procedures. The most appropriate approach is thus to concentrate on ways to improve efficiency through decreasing ramp closure times, without compromising safety. To do this, we will attempt to quantify the actual closure costs, with emphasis on the closure costs “per minute” after the initial ramp shut- down. These closure cost estimates will ultimately be used to evaluate any proposed improvements to current lightning de- tection and warning systems either to not initiate an unneeded closure or to try to get an airport back into full operation as soon as possible when lightning strikes no longer present a danger. Given the general unpredictability as to where and when a lightning strike will occur, there will always be a re- quired minimum closure time before ramp operations can be resumed safely. This implies that there will always be a signif- icant cost associated with the initial alarm declaration and the clearing of the ramp. Analysis of Costs Two main cost categories were segmented for analysis. The first concentrates on the costs at the local airport where the lightning is occurring. These costs will include the opportu- nity cost of lost passenger time, which are applicable in events of any duration. There may also be direct costs to the airline, depending on whether they need to pay the ramp workers overtime or whether extra fuel is used by planes waiting on the ramp for a gate to become available. The second cost category evaluates the “ripple effect” that is caused by downstream delays. These may include addi- tional opportunity cost of passenger time caused by missed connections, as well as direct costs of extra flight time in- curred in repositioning planes for the next day. The best economic estimates we found originate from an FAA report (27). The remaining input values would be sensi- tive to each particular situation, depending on airport and airline. The estimated values made available in the FAA re- port are presented in Table 2. The hourly cost of aircraft delay shown in Table 2 is a representative value. Costs will vary by aircraft type. Various aircraft and their block hour operating costs as of 2001 and 2002 are shown in Table 3. Case Studies Closure costs will always be a function of the amount of aircraft operations affected, the geographical area and lightning climatology, and flight schedule. To get a balanced perspective, we chose two airports for detailed case study analysis—Chicago O’Hare International Airport (ORD) in Illinois, and Orlando International Airport (MCO) in Florida. As shown in Table 4, ORD is a high-activity airport located in the upper Midwest in an area of large spring and summer storms. MCO is a medium-activity airport in the southeast, near the climatological maximum for U.S. lightning activity. Lightning Delay Analysis Because reliable records on ramp lightning closures at air- ports are not available, we obtained from Vaisala NLDN lightning strike data within 10 statute miles of both ORD and MCO for the calendar year 2006. We then constructed a synthetic closure history for each airport based on a strict imposition of the 30/30 rule. As discussed in Chapter 1, the 30/30 rule recommends that outdoor activities be cur- tailed following a cloud-to-ground lightning strike within 36 Item Value ($) Value of Human Life 3.0 million Average Labor Cost, Ramp Rate 13.03/hr Hourly Cost of Aircraft Delay 1,524/hr/aircraft Rate of Delay Per Aircraft (fuel, etc.) 2,290/hr/aircraft Rate of Labor Delay 814/hr Value of Passenger Time 28.60/hr Table 2. Standard economic values.

6 statute miles (corresponding to 30 sec of time delay between the visible lightning strike and the sound of the thunder) and not resumed until 30 min after the last light- ning strike within 6 mi. Based on the sequential time and location history of nearby lightning strikes, we calculated the distance of each stroke from the airport reference point and determined closure and all-clear times for both airports. The results of this exercise are summarized in Appendix A. It should be noted that all data contained in the following analyses and shown in Tables 5 through 12 were derived using the synthetic lightning duration technique employed on the Vaisala lightning detection data and therefore do not repre- sent actual reported lightning duration delays. O’Hare International Airport The results for ORD indicate there would have been 68 ramp closures in 2006, with a total closure time of 70.8 hours, or approximately 1% of the time. Figure 18 pres- ents the full histogram of the length (time duration) of each ramp closure based on this simulation. The synthetic closure distribution is strictly based on the 30/30 rule in a hypothet- ical system without electric field mills. Table 5 shows the distribution of synthetic lightning in- duced ramp closures for ORD stratified by time of day and season of the year. When events overlapped a time period, the event was assigned to the time period it most affected. Table 5 indicates a slight preference for lightning events to occur in the late afternoon. As would be expected, lightning events are most frequent in the summer and least frequent in the winter. We caution, however, that this analysis contains only 1 yr of data, so it may not be generally representative of the long-term diurnal duration climatology. Nonetheless, based on NOAA’s 2006 climate summary and 30-yr normals for thunderstorm events, 2006 was a relatively normal year, with 42 thunderstorm events compared with a normal of 40 events. This suggests that the 68 lightning-induced ramp closures at ORD that we deduced from the data are consistent with the climatological record of thunderstorms for the area. As illustrated in Figure 18, a majority of the closures are estimated to have been for 45 min or less, with only 14 clo- sures exceeding 90 min and only 3 closures exceeding 3 hr. The data also indicate several days when there was more than one closure because of recurring lightning events. We con- clude that these results indicate that occurrences of long- duration delays that could potentially cause en route delays and ground holds in the National Airspace System are infre- quent, but may occur. It is important to note, however, that in most cases these extreme events will be caused by large mesoscale convective systems that are either stationary over the airport, extend over large areas, or generate repeated lines of storms across the airport. These events will gener- ally result in en route and terminal airspace delays irre- spective of their effect on ramp operations. Because these events are infrequent and are likely to be associated with a general disruption of the National Airspace System, these costs are more appropriately addressed in an analysis of thunderstorms along the flight path rather than lightning 37 Aircraft Type Block Hour Cost ($/hr) Commercial Passenger Service Airbus 319 1,960 Airbus 320 2,448 ATR 72 1,401 Beach 1900 676 Boeing 727-200 2,887 Boeing 737-100/200 2,596 Boeing 737-300/700 2,378 Boeing 737-500 2,271 Boeing 737-800 2,201 Boeing 757-200 3,091 British Aerospace 146 2,776 Canadair CRJ-145 1,072 Canadair CRJ-200 864 Dehavilland Dash 8 970 Embraer 120 Brasilia 861 Embraer ERJ-145 996 Fokker 100 2,406 Jetstream 31/32 544 Jetstream 41 759 McDonnell Douglas 9-30 (DC 9-30) 2,280 McDonnell Douglas 80 (MD-80) 2,630 McDonnell Douglas 87 (MD-87) 2,300 General Aviation—Corporate and Air Taxi Small Business Jet 500 Mid-Size Business Jet 750 Large Business Jet 1,000 General Aviation—Private Single-Engine Piston 100 Multi-Engine Piston 200 Multi-Engine Turboprop 300 Rotorcraft 250 Table 3. Aircraft block hour operating costs.

38 Airport Operations/Day Chicago-O’Hare International Airport, IL (ORD) 2,662 Dallas-Ft. Worth International Airport, TX (DFW) 1,915 Denver International Airport, CO (DEN) 1,603 Phoenix-Sky Harbor International Airport, AZ (PHX) 1,494 Charlotte-Douglas International Airport, NC (CLT) 1,421 Orlando International Airport, FL (MCO) 977 Tampa International Airport, FL (TPA) 716 Pittsburgh International Airport, PA (PIT) 649 Note: Operations/day includes those operations conducted by air carrier, air taxi, general aviation, and military aircraft. An aircraft operation is either a takeoff or a landing. Table 4. Aircraft operations levels at selected airports. Duration 27 12 6 6 3 5 6 0 3 0 5 10 15 20 25 30 30 31-45 46-60 61-75 76-90 91-120 121-150 151-180 181+ Duration, min Co un t Figure 18. Duration of lightning delays at ORD during 2006. strikes in the vicinity of the ramps, and thus were not in- cluded in our cost analysis. Table 6 summarizes the per-minute values used to estimate the closure costs resulting from lightning events. Using these values, we calculated per-minute cost values for a sample short duration (less than 60 min), medium duration (61 to 135 min) and long duration (greater than 136 min) event. The number of affected aircraft and the diurnal pattern of flight operations were estimated from the material available on the FlightAware website (www.flightaware.com). The pattern consists of mini- mal operations activity (an operation is defined as a takeoff or a landing) between the hours of 12 a.m. and 5 a.m. Then there is an increase in operations, reaching approximately 100/hr by 7 a.m. Hourly operations levels remain in the 80 to 100 range throughout the day until approximately 10 p.m., when activity declines rapidly. The number of aircraft affected at ORD was estimated at 90 planes per hour based on the typical daily operation statistics shown FlightAware’s graphics for ORD. In our analysis, we assumed there would be no direct op- erating costs to the airlines for short duration events because they should be able to catch up without incurring additional costs. For medium and long duration events, the direct local airport costs were obtained by multiplying the number of planes affected times the number of ramp workers per plane times the overtime rate of ramp workers times one-half of the delay. The reason for using one-half of the delay was to

account for the fact that airlines would be able to catch up somewhat faster after a delay without occurring the full duration of delay in overtime cost. The above factors are pre- sented in the following equation: DLAC = 1/2(NPA ∗ NRPP ∗ ORRW ∗ DD) where DLAC = direct local airport costs, NPA = number of planes affected by delay, NRPP = number of ramp workers per plane, ORRW = overtime rate of ramp workers, and DD = duration of delay. The ripple effect direct costs are caused by the added end- of-day cost of repositioning planes. This cost was calculated by multiplying the operating cost of the Boeing 737-500 times the number of planes affected times the repositioning time (as shown in Table 6). REDC = N(OCOPN ∗ NPIRN) ∗ RT where REDC = ripple effect direct cost, N = number of aircraft affected of type N, OCOPN = hours operating cost of aircraft type N, and RT = repositioning time. The local airport opportunity costs were calculated as the per-minute value of passenger time multiplied by the num- ber of passengers per aircraft times the number of aircraft affected by the delay times the duration of delay. Based on 39 Hour Dec-Feb Mar-May Jun-Aug Sep-Nov Total 0-3 2 1 1 4 3-6 3 4 7 6-9 1 3 1 5 9-12 2 2 2 2 8 12-15 3 1 3 3 10 15-18 4 4 5 13 18-21 3 6 3 12 21-24 3 4 3 10 Total 5 16 26 22 69 Table 5. ORD lightning event frequency stratified by time of day and season of year. Cost Item (Based on Boeing 737-500) Value Passengers per plane $100 Value of passenger time $0.478/min Passenger time ripple effect 1.5 times local airport passenger effect Ramp workers standard pay rate $13.03/hr Ramp workers overtime pay rate $19.55/hr Average ramp workers per plane 6 Operating cost for Boeing 737-500 $2,271/hr Aircraft repositioning time 0 for short duration 1 hr for medium duration 2 hr for long duration Note: The typical duration of an event was deduced from the ORD 2006 NLDN data. Table 6. ORD per-minute cost values.

information contained in the ATC-291 report (26), the rip- ple effect cost or opportunity ripple factor applied for pas- senger time was assumed to be 1.5 times the local airport effect, as shown in the equation below: LAOC = VPT ∗ NOPID ∗ DD where LAOC = local airport opportunity cost, VPT = value of passenger time, NOPID = number of passengers incurring delay, and DD = duration of delay. The ripple effect opportunity cost may be determined from the following equation: REOC = LAOC ∗ ORF where REOC = ripple effect opportunity cost, LAOC = local airport operating costs, and ORF = opportunity ripple factor. The monetary per-minute cost calculations are shown in Table 7. The last column indicates the per minute cost and is calculated as: PMC = TC/DD where PMC = per minute cost, TC = total cost of delay, and DD = duration of delay. These results indicate the per-minutes costs increase with the duration of delay. Fortunately, medium and long dura- tion delays during the period 7 a.m. to 10 p.m. at ORD are relatively infrequent, occurring only 16 times during 2006, as shown in Table 7. Medium and long duration events present higher incre- mental per-minute potential savings because more costs come into play and more aircraft and people are affected. However, short duration events are more frequent. The po- tential delay reduction is likely not correlated to the duration of the event. Using the 2006 data, we estimated the potential savings of a 10-min reduction in delay for each duration lightning event. It should be noted that we did not include in this analysis lightning events between the hours of 10 p.m. and 7 a.m. because operations during those hours are much less than during the core 7 a.m. to 10 p.m. local time. Reduc- tion in lightning delays during these “off” hours should pro- vide minimal cost savings. The potential minutes saved for each duration event were calculated by multiplying the number of events times the as- sumed 10-min savings. As shown in Table 8, the total poten- tial savings over a period of 1 yr (using 2006 as the proxy) would be slightly over $6 million. The savings for each duration are calculated by multiply- ing the per-minute costs (savings) for each duration by the minutes saved. The total minutes saved and the total dollar savings are then obtained by adding the savings for each du- ration. The average per-minute savings is then calculated by dividing the total dollar savings by the total per minute sav- ings. In equation form, this is TPMSA = (SDMS ∗ SDV + MDMS ∗ MDV + LDMS ∗ LDV) /(SDMS + MDMS + LDMS) where TPMSA = total per minute savings, SDMS = short duration minutes saved, SDV = short duration per-minute value, MDMS = medium duration minutes saved, MDV = medium duration per minute value, LDMS = long duration minutes saved, and LDV = long duration per-minute value. 40 Local Airport Cost ($) Ripple Effect ($) Type of Event Typical Duration (min) No. of Aircraft Affected Direct Opportunity Direct Opportunity Total Cost ($) Per Minute Cost ($) Short 30 45 0 64,350 0 96,525 160,875 5,362 Medium 120 180 21,109 1,029,600 408,780 1,544,400 3,003,896 25,032 Long 210 315 55,409 2,702,700 715,365 4,054,050 7,527,524 35,845 Table 7. Typical monetary values for various duration events during the core 7 a.m. to 10 p.m. period at ORD.

Orlando International Airport Paralleling our analysis for ORD, we analyzed 2006 NDLN data from Vaisala to produce a synthetic ramp closure data set for MCO using the same process as described for ORD. The synthetic delay information for MCO is presented in Ap- pendix A. The results of the Orlando lightning event duration analysis for 2006 are shown in Figure 19. As would be expected because of the location in the most active lightning region in the U.S., Orlando (MCO) had almost twice as many lightning events as ORD (126 compared with 68). The total minutes of delay were also higher (143 hr for MCO compared to 71 hr for ORD). The duration pattern of MCO, summarized in Table 9, indicates a tendency for longer duration events than occur at ORD. At ORD, 66% (45/68) of 2006 lightning events were less than 1 hr in duration, whereas MCO reported 60% (75/126) of the lightning events in 2006 were less than 1 hr. There is also a higher frequency for summertime lightning events at MCO (62%) compared with ORD (38%). While the peak period for storms at ORD is 3 p.m. local time, the peak period for storms at MCO is 6 p.m. to 9 p.m. local time. These differences are probably the result of the different climate zones for two airports. ORD is in a continental climate, af- fected more frequently than MCO by synoptic type storms, whereas MCO is affected by more local weather factors, such as summertime sea breeze convergence zones. MCO reports approximately 33% of the daily flight oper- ations that ORD reports, with MCO averaging approximately 40 flight operations per hour between the hours of 7 a.m. and 8 p.m., with a rapid decline in operations after 8 p.m. Mini- mal activity is seen overnight, and flight operations begin to increase at approximately 5 a.m. As shown in Table 10, 52 of the 2006 lightning events occurred overnight between the hours of 9 p.m. and 6 a.m. Because flight operations are very limited during these hours, approximately 41% (52/126) of the synthetic 2006 lightning delays would have resulted in minimal economic costs to the airport and airlines. 41 Type of Event Number of Events Total Annual Minutes Delay Potential Annual Minutes Saved Per-Minute Cost ($) Total Annual Potential Savings ($) Short 35 1,275 350 5,362 1,876,700 Medium 13 1,258 130 25,032 3,254,160 Long *Weighted average, calculated with Total Annual Potential Savings divided by Potential Annual Minutes Saved. 3 531 30 35,845 1,075,350 All 51 3,064 510 12,169* 6,206,210 Table 8. Estimate of potential savings from a 10-min improvement in lightning delays during the 7 a.m. to 10 p.m. core period at ORD. 35 26 14 6 10 15 11 6 3 0 5 10 15 20 35 40 25 30 30 31-45 46-60 61-75 76-90 91-120 121-150 151-180 180+ Duration (min) Duration Co un t Figure 19. Duration of lightning delays at MCO during 2006.

Following the approach taken for ORD, monetary values were calculated for typical duration events at MCO. The pri- mary difference in the results between ORD and MCO is caused by the difference in the number of aircraft affected by the delay. The results for the MCO monetary value analysis are presented in Table 11. Again, following the analysis used for ORD, Table 11 esti- mates the potential savings of a shortening of the duration of each ramp closure event by 10 min. The potential savings from a 10-min improvement in delay time during peak hours at MCO is approximately $2.8 million, compared with the $6.2 million calculated for ORD. Shorter Duration Events Consideration was given to reducing the 60-min or less lightning delay interval in the cost analysis to a shorter time in- terval. In fact, as shown in Figure 18 and Figure 19, a majority of the duration delay events are for periods of less than 60 min. This would argue for a further stratification of the monetary value analysis for “short duration” delays to include an analy- sis for delays of less than 30 min or perhaps less than 15 min. Certainly, for an affected disgruntled passenger, any delay over 30 min would not be considered “short duration.” Notwithstanding this possible interpretation of delay time per lightning event, it is recognized that the focus of the re- search is on the economic impact to the airline and the air transportation system. The key point here is that airlines can choose to undertake certain mitigation actions, such as re- scheduling flights and crews at other airports, to compensate for missed connecting flights attributable to lightning delays at an airport. However, because this takes time to analyze and implement, anticipated short-duration events are generally accepted and managed as best as possible. Furthermore, delays of less than 60 min produce comparatively minimal costs to the airline industry when compared with costs for delays of greater than 60 min. As indicated in Table 8 and Table 11, the per- minute cost of a short duration delay averages 21% of that for medium delay events and 14% of that for long delays. Generating shorter duration delays would thus have the effect of reducing an already minimal cost contribution. Con- sequently, we have chosen to use the three delay event strati- fications indicated above because they provide a clearer view of which events produce the major costs and therefore pro- vide the focus for improvement. 42 Hour Dec-Feb Mar-May Jun-Aug Sep-Nov Total 0-3 1 1 5 3 10 3-6 1 2 2 5 6-9 1 1 2 9-12 2 1 1 4 12-15 2 1 1 4 15-18 1 11 1 13 18-21 2 2 38 9 51 21-24 3 5 20 9 37 Total 12 12 78 24 126 Local Airport Cost ($) Ripple Effect ($) Type of Event Typical Duration (min) No. of Aircraft Affected Direct Opportunity Direct Opportunity Total Cost ($) Per Minute Cost ($) Short 30 20 0 28,600 0 42,900 71,500 2,383 Medium 120 80 6,254 457,600 181,680 686,400 1,331,934 11,099 Long 210 140 28,371 1,401,400 317,940 2,102,100 3,849,811 18,332 Table 9. MCO lightning event frequency stratified by time of day and season of year. Table 10. Typical monetary values for various duration events during the 7 a.m. to 8 p.m. core period at MCO.

30/15 Analysis To evaluate the sensitivity of the predicted economic im- pact on the interval between the last lightning strike and a return to normal operations, we conducted an additional set of analyses reducing the all-clear time from 30 min to 15 min after the last reported lightning strike within 6 mi of the airport. Based on the surveys reported in Chapter 2, this time interval may be more common than the “stan- dard” 30 min used for general outdoor activities. This “30/15” analysis was conducted for the summer months (June–August) when lightning activity is most frequent. The 30/15 summer 2006 delay data for ORD and MCO are included in Appendix A. A summary of these analyses are presented in Table 12. The rule change from 30/30 to 30/15 results in a slight in- crease in the number of events because of a few cases where the airport would be opened and then quickly closed again under the 30/15 rule (causing two events instead of one to be recorded), while the airport would stay have stayed closed under the 30/30 rule. While this could represent an increased hazard for ramp personnel, it results in a significant reduc- tion in delay time, totaling 354 min at ORD and 1,568 min at MCO. The corresponding cost impact of the 30/15 summer (June–August) improvement for both ORD and MCO air- ports was calculated by analyzing the improvement in total delay time for each duration event during peak operating hours only and then multiplying the duration delay savings in minutes by the previously calculated per-minute delay costs. When events overlapped peak hours and nonpeak hours, the duration of the event was only taken as the duration that occurred during the peak hours. Note that in the ORD analy- sis, the single long duration event ended after the peak-hour period, resulting in no delay savings for that event. The results for ORD, shown in Table 13, indicate a potential savings of approximately $3.4 million for the summer, based on hypothetical implementation of the 30/15 rule. The results for MCO are perhaps more intriguing. In this case, the change would hypothetically have increased the number of short-term events from 24 to 36, while reducing the number of medium- term events from 12 to 8. The shorter “all-clear” time provides limited openings in the ramp closures and reduces the number of longer and more costly delays. In our hypothetical analysis, this results in a potential savings of $6.3 million at MCO for the summer of 2006, as shown in Table 14. Findings This cost analysis indicates that delay cost impacts are com- plex. They are a function of several factors, including the activity levels and mix of aircraft operating at an airport, the number of lightning events, the timing of the lightning event, the type of lightning event (local convective or associated with broad- scale flow), the duration of the lightning event, and the rules the airline/airport operators use in issuing the “all clear” signal to resume ramp activity. The analysis also indicates that the annual value of new technologies or new procedures that could reduce ramp lightning delays, although varying by airport, could be substantial. The potential savings produced by a reduction of 43 Type of Event Number of Events Total Annual Minutes Delay Potential Annual Minutes Saved Per Minute Cost ($) Total Annual Potential Savings ($) Short 40 1,385 400 2,383 953,200 Medium 15 1,674 150 11,099 1,664,850 Long *Weighted average, calculated with Total Annual Potential Savings divided by Potential Annual Minutes Saved. 1 184 10 18,332 183,322 All 56 3,243 560 5,002* 2,801,372 Table 11. Estimate of potential savings from a 10-min improvement in lightning delays during the 7 a.m. to 8 p.m. core period at MCO. Number of Events By Rule Minutes of Total Delay By Rule Airport 30/30 30/15 Change 30/30 30/15 Change Chicago (ORD) 26 28 2 1,922 1,568 -354 Orlando (MCO) 78 87 9 5,544 3,976 -1,568 Table 12. Impact of replacing the 30/30 rule with a 30/15 rule.

even a few minutes would likely be sufficient to more than cover the cost of introducing improved technology or practices. As a general guideline, the costs of direct lightning dura- tion delays at any given airport may be approximated by the following equation: TALAC = NPAD ∗ NRPP ∗ ORRW ∗ TAD + VPT ∗ NOPID ∗ TAD where TALAC = total annual local airport cost, NPAD = number of planes affected during a delay, NRPP = number of ramp workers per plane, ORRW = overtime rate of ramp work, TAD = total annual delay minutes for delays over 60 min (medium- and long-term delays), VPT = value of passenger time, and NOPID = number of passengers per plane incurring delay. When compared against the potential cost of implement- ing improved lightning monitoring and forecasting systems, the analysis indicates that the annual value of new tech- nologies or procedures for reducing ramp lightning delays, although varying by airport, could be substantial. The po- tential savings produced by a reduction of even a few minutes would likely be sufficient to more than cover the cost of introducing the improved technology or procedures. Because safety of the ramp workers is the paramount con- cern, it appears the airlines will likely err on the side of cau- tion in closing ramp operations. This suggests that the most likely path to improved operational efficiency is in being able to sound an “all clear” as quickly as possible after the initial event, so long as it can be done without compromising safety. 44 Delay By Rule Savings With 30/15 Rule Delay Duration 30/30 30/15 Change Per Minute ($) Total ($) < 60 min 819 810 9 2,383 21,477 60-180 min 1,415 847 568 11,099 6,304,322 > 180 min 0 0 0 18,332 0 Total 2,234 1,657 577 10,963* 6,325,799 *Weighted average, calculated with Total Savings divided by Total Change. Table 14. Potential savings with 30/15 rule, MCO June–August 2006. Delay By Rule Savings With 30/15 Rule Delay Duration 30/30 30/15 Change Per Minute ($) Total ($) < 60 min 421 284 137 5,362 734,594 60-180 min 514 408 106 25,032 2,653,392 > 180 min 184 184 0 33,845 0 Total 1,120 876 243 13,942* 3,387,986 *Weighted average, calculated with Total Savings divided by Total Change. Table 13. Potential savings with 30/15 rule, ORD June–August 2006.