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69 INTRODUCTION DUWK tour operators typically outfit their boats with canopies to provide passenger comfort against the sun, rain, and wind. Tour operators briefing the committee stressed the importance of canopies for their tour businesses. However, canopies can be a major impediment to safe escape during an emergency. For small passenger vessels, a canopy covering the open seating area creates an enclosed passenger area and can slow or prevent escape, increas- ing the risk of injury and death. Because DUKWs have a greater risk of sinking rapidly, the risk that a DUKWâs canopy will interfere with escape is even more significant. Moreover, canopies can complicate the decision to don a life jacket during an emergency to such an extent that it is not even clear whether it is advisable for passengers to wear or don life jackets before escaping the boat. The National Transportation Safety Board (NTSB) and the United States Coast Guard (USCG) have both recommended that DUKW operators remove canopies until a design can be approved that does not restrict the escape of passengers and crew. This chapter explains the history of these recommendations and the conclusions of other studies on the risks posed by canopies. It then reviews some of the alternative types of canopies devel- oped in recent years that attempt to mitigate the risks in different ways. The chapter then proposes additional canopy designs for further explora tion. The committee considers a ârestrictive canopyâ to be any canopy design that has not been demonstrated in a practical test to provide the equivalent 5 Canopies and Escape During Emergencies
70 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS in safety to no canopy. Restrictive canopies include any canopy that makes it inadvisable to wear a life jacket during the waterborne part of a tour. CANOPIES, LIFE JACKETS, AND LOSS OF LIFE Canopies have been found to be a contributing factor to the loss of life in the Miss Majestic and Stretch Duck 7 sinkings. Survivors reported fighting their way through or past the canopies, and, in both tragedies, victims were recovered still in the vessels. This section reviews the presence of canopies and the donning of life jackets for the three casualty events in the United States with fatalities. In these three casualty events, life jackets were stored in the canopies directly above the passengers, yet only a few passengers managed to don a life jacket even partially before being submerged. There has not been a fatality event on a DUKW in the United States where passengers were wearing life jackets at the time the vessel began sinking. Counter- intuitively, this has probably been a benefit for the survivability of some passengers when not wearing a life jacket expedited their escape from the restrictive canopy. If a small passenger vessel without a canopy sinks, passengers wearing life jackets will stay floating on the surface as the boat sinks beneath them. If a small passenger vessel with a canopy sinks, the buoyancy of the life jacket may force the wearer up against the inside of the canopy. To escape, they must swim down against the force of the life jacket and out a canopy window. The presence of a canopy creates a situation where it is not neces- sarily safer to be wearing a life jacket. The Miss Majestic began sinking with all 20 passengers and the master still on board. Of the 13 dead, 7 were found still in the boat. The 8 sur- vivors managed to swim out the side windows to safety. The canopyâs supports defined the side windows, with a height of 28 inches. However, when the canopyâs side curtains were in the rolled-up position, as they were at time of sinking, the window height was reduced to 21 inches. The life jackets were stored in the canopy, and the master and a passenger reported difficulty trying to remove them. None of the passengers succeeded in don- ning a life jacket themselves or putting one on a child.1 The NTSB found that the Miss Majesticâs canopy was a âmajor impedi- mentâ to passenger survival and that wearing life jackets for the waterborne part of a tour would âenhance the safety of passengers on board DUKWs 1 NTSB, 2002, âSinking of the Amphibious Passenger Vessel Miss Majestic, Lake Hamilton, Hot Springs, AR, May 1, 1999,â Marine Accident Report NTSB/MAR-02/01, April 2. https:// www.ntsb.gov/investigations/AccidentReports/Reports/MAR0201.pdf.
CANOPIES AND ESCAPE DURING EMERGENCIES 71 without adequate reserve buoyancy where canopies have been removed.â2 The USCG investigation also concluded âthat the donning of life jackets would have prevented escape from under the canopy and led to additional deaths.â3 After the Stretch Duck 7 sinking, the NTSB again concluded that the canopy and side curtains likely contributed to the loss of life and that if the passengers had donned life jackets, the life jackets âwould have cre- ated an impediment to escapeâ that âcould have resulted in additional fatalities.â Of the 17 deceased, 9 bodies were recovered under water, including 1 still in the boat.4 As the storm began to hit Table Rock Lake, Stretch Duck 7âs master lowered the side curtains to protect the passengers from the wind and rain. The master did not order the passengers to don life jackets when he cut short the tour and headed for shore. As the vessel began quickly sinking, the master only managed to release one of the canopyâs side curtains before the incoming water swept him out of the boat. Fortunately for the passengers who reported floating up to the underside of the canopy, the canvas became partially dis- lodged, and some managed to escape through the opening. On the recovered vessel, 41 of 56 life jackets were still connected to Stretch Duck 7âs canopy.5 For the DUKW 34 collision, although the canopy was not consid- ered a contributing factor to the loss of life, it was damaged in the col- lision. The canopy supports on the port side were bent, two of them by about 45 degrees, toward the interior of the passenger compartment. The port-side roller curtain was also damaged so that it hung from one of its mountings.6 Of the 37 people on board DUKW 34, only 1 evacuated in advance of the collision. The DUKWâs master had not ordered the passengers to don life jackets when he anchored the vessel. In the minute before the collision, passengers started to scramble for life jackets, but only a few managed to get them over their heads, and no one donned and fully fastened a life jacket before being hit by the barge. Fortunately, the canopyâs side curtains were 2 NTSB, 2002, âSinking of the Amphibious Passenger Vessel Miss Majestic, Lake Hamilton, Hot Springs, AR, May 1, 1999,â Marine Accident Report NTSB/MAR-02/01, April 2, 2002. 3 USCG, 1999, âInvestigation into the Circumstances Surrounding the Sinking of the M/V Miss Majesticâ¦,â September 29. https://www.dco.uscg.mil/Portals/9/DCO%20Documents/5p/ CG-5PC/INV/docs/boards/dukw.pdf. 4 NTSB, 2020, âSinking of Amphibious Passenger Vessel Stretch Duck 7, Table Rock Lake, near Branson, MO, July 19, 2018,â Marine Accident Report NTSB/MAR/20-01, April 28. https://www.ntsb.gov/investigations/AccidentReports/Reports/MAR2001.pdf. 5 NTSB, 2020, âSinking of Amphibious Passenger Vessel Stretch Duck 7, Table Rock Lake, near Branson, MO, July 19, 2018,â Marine Accident Report NTSB/MAR/20-01, April 28. 6 NTSB, 2011, âCollision of Tugboat/Barge Caribbean Sea/The Resource with Amphibious Passenger Vessel DUKW34, Philadelphia, PA, July 7, 2010,â Marine Accident Report NTSB/ MAR-11/02, June 21. https://www.ntsb.gov/investigations/Pages/DCA10MM025.aspx.
72 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS rolled up at the time of the collision because it was a nice day. Those with life jackets in hand at the time of the collision reported losing grasp of them during the sinking. Some survivors were able to grab hold of floating life jackets once they reached the surface of the water.7 REGULATIONS AND NVIC 1-01 Regulations and guidance for canopies aim to prevent canopies from inter- fering with escape during an emergency. Navigation and Vessel Inspection Circular 1-01 (NVIC 1-01) was created to implement the recommendations, including for canopies, after the sinking of the Miss Majestic. Among its recommendations, NIVC 1-01âs guidance remedies the small effective height of the windows that helped trap Miss Majesticâs passengers by recommend- ing a vertical distance of 32 inches. Because of a DUKWâs small size, Subchapter T, 177.500, Means of Escape, requires only one means of escape, and NVIC 1-01 stipulates that the primary means of escape is over the side. If a canopy is present, the primary means of escape becomes through the canopy âwindowsâ as delineated by the supports holding up the canopy. NVIC 1-018 directly addresses canopies by outlining design specifications allowing safe egress over the side: Canopy supports should be positioned to allow the majority of passengers unobstructed egress. If a canopy support is located directly adjacent to a passengerâs seat it should be shown, through a practical test, that the passenger can adequately egress the vehicle. The window framing vertical distance should be sufficient for a passenger to exit while wearing a life jacket. A vertical distance of 32 inches from gunwale to canopy appears sufficient for most installations. Overhead storage of life jackets should not impede the egress of passengers. In addition, NVIC 1-01 advises that side curtains âshould be able to be opened with minimal force, generally by a simple action by one person.â NVIC 1-01 does not anticipate escape through the âroofâ of the canopy itself.9 Because the primary means of escape is over the side, NVIC 1-01 also allows more cramped conditions in the passenger compartment, putting even more importance on easily retrieving life jackets and exiting over the sides. 7 NTSB, 2011, âCollision of Tugboat/Barge Caribbean Sea/The Resource with Amphibious Passenger Vessel DUKW34, Philadelphia, PA, July 7, 2010,â Marine Accident Report NTSB/ MAR-11/02, June 21. 8 NVIC 1-01, p. 23. https://www.dco.uscg.mil/Portals/9/DCO%20Documents/5p/5ps/ NVIC/2001/n1-01.pdf. 9 NVIC 1-01, p. 23.
CANOPIES AND ESCAPE DURING EMERGENCIES 73 Despite the stipulation that passengers should escape over the side, USCG also recognizes that âthis goes against human nature, which is to exit in the same manner one enters.â For most DUKWs, passengers enter over the stern and will assume that the exit is also at the stern. Because of the discrepancy between ingress and safe egress locations, NVIC 1-01 stresses that âthe master should give specific instructions to the passengers during the safety orientation concerning the method of escape from the vehicle.â10 RECOMMENDATIONS FROM STUDIES AND INVESTIGATIONS The hazard canopies pose to safe escape applies to all small passenger vessels, not just DUKWs. Investigations and studies conducted by NTSB, USCG, and the Worcester Polytechnic Institute over the past 20 years all agree that canopies are a significant safety hazard on small passenger vessels if not constructed for easy egress. After the sinking of the Miss Majestic, NTSB issued Safety Recommen- dation M-02-2 directed to the attention of USCG and the states of New York and Wisconsin. The recommendation highlighted the relationship between reserve buoyancy (Chapter 3) and canopies: Until such time that owners provide sufficient reserve buoyancy in their amphibious passenger vessels so that they will remain upright and afloat in a fully flooded condition (by M-02-1), require the following: (1) removal of canopies for waterborne operations or installation of a Coast Guard- approved canopy that does not restrict either horizontal or vertical escape by passengers in the event of sinking.11 USCG concurred with the intent of the recommendation and developed the canopy guidelines in NVIC 1-01 described in the previous section. In 2003, NTSB expressed its dissatisfaction with USCGâs approach, noting that NTSBâs recommendation was that USCG either require the removal of canopies or create additional design requirements, not advisory guidelines. At the request of USCG, students at the Worcester Polytechnic Insti- tute produced âStandards for Enclosed Canopies on Small Passenger Ves- selsâ in 2009,12 which provides a full review and analysis of the types of canopies, applicable regulations, their role in casualties, and impacts on 10 NVIC 1-01, p. 23. 11 NTSB, 2019, Recommendation M-02-2 as reprinted in NTSB, âImproving Vessel Surviv- ability and Passenger Emergency Egress of DUKW Amphibious Passenger Vessels,â Marine Safety Recommendation Report MSR-19-01, November 6. 12 See https://web.wpi.edu/Pubs/E-project/Available/E-project-121609-190318/unrestricted/ USCG_Final_IQP.pdf?_ga=2.149754993.67315947.1634477406-1311220223.1634477406.
74 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS passenger behavior. The committee highlights four of their findings and recommendations to improve canopies: 1. Donning of bulky Type 1 life jackets while inside a canopy with escape routes of insufficient size can lead to entrapment during a flooding event, as the life jacket will hold the passenger up against the canopy and prevent them from diving out through an opening. 2. Side windows can be a major impediment to escape and, if fitted, should have an emergency release mechanism that is easily operable. 3. Darkness inside the canopy while flooding can lead to confusion and disorientation. Underwater LED lights should be installed that would be activated automatically in an emergency. 4. Passenger education on how to act in an emergency is critical before an emergency situation occurs. Crew training and signage are also important to provide direction to passengers in an emergency. After the sinking of Stretch Duck 7, NTSB adopted Safety Recom- mendation M-19-16 in 2019. The agency again recommended that USCG require the removal of canopies, but this time without presenting the option that perhaps the design of canopies could be improved: For DUKW amphibious passenger vessels without sufficient reserve buoy- ancy (commonly referred to as original and/or âstretchâ DUKWs), require the removal of canopies, side curtains, and their associated framing dur- ing waterborne operations to improve emergency egress in the event of sinking.13 USCG issued a similar recommendation in Marine Safety Informa- tion Bulletin 15-20, issued April 22, 2020, which stated âthat vessel owners and operators of DUKW passenger vessels remove canopies, side curtains, and associated overhead framing to improve emergency egress for passengers and crew.â14 However, USCG made canopy removal a rec- ommendation, not a mandate, so operators could still retain canopies if desired. 13 NTSB, 2019, âImproving Vessel Survivability and Passenger Emergency Egress of DUKW Amphibious Passenger Vessels,â Marine Safety Recommendation Report MSR-19-01, November 6. 14 USCG, 2020, âRecommendation for DUKW Passenger Vessel Canopy Removal,â Marine Safety Information Bulletin 15-20, April 22. https://www.dco.uscg.mil/Portals/9/DCO%20Documents/5p/ MSIB/2020/MSIB-15-20_Recommendation%20for%20DUKW%20Passenger%20Vessel%20 Canopy%20Removal.pdf.
CANOPIES AND ESCAPE DURING EMERGENCIES 75 TYPES OF CANOPIES IN USE DUKWs currently use a range of canopy designs, and many of the designs consider the decades of concerns that canopies pose a hazard to passengers in an emergency. Canopies generally consist of canvas or plastic material stretched across metal framing and supported by multiple vertical supports. Some DUKWs also use side curtains made of clear plastic. This section reviews the types of canopies and side curtains in use on DUKWs currently or in the recent past to examine how canopies create impediments to escape and how design modifications aim to mitigate these hazards. Some DUKW operators forego side curtains, which allows easier escape over the side of the vessel. However, close spacing of the vertical canopy supports may still interfere with escape, particularly if passengers are wear- ing bulky life jackets. For DUKW operators that continue to use side cur- tains, there are designs that allow each window to be opened individually by a person sitting or standing adjacent to the window, instead of using a single mechanism to drop the entire side curtain at once. The area under the canopy roof is often used to store life jackets, as shown in Figure 5-1. This arrangement puts a life jacket above each pas- senger, within reach if they stand. However, disabled passengers or children unable to reach the overhead life jackets would need to be assisted by others. For operators, storing life jackets in the canopy makes it easier to use the limited amount of deck area for passenger seating. FIGURE 5-1 Stowage of life jackets under the canopy from Stretch Duck 7. SOURCE: https://www.ntsb.gov/investigations/AccidentReports/Reports/MAR2001. pdf.
76 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS Canopy with Rolldown Side Curtains The canopy on the Stretch Duck 7, shown in Figure 5-2, included two side curtains, each made out of a single sheet of clear plastic that could be rolled down and up as needed. Figure 5-3 shows the plastic side curtains in the down or deployed condition. In emergencies, each curtain is released by its corresponding lever located on each side of the vessel. The release mecha- nism does not roll up the curtain; instead, the release mechanism causes the curtain to disengage at the top and fall away. On the Stretch Duck 7, one release lever was located on the port side above the driverâs seat and one in the corresponding location on the starboard side. The driverâs seat is located directly behind the captainâs seat. The starboard release mechanism was not within easy reach of either the captainâs or driverâs seat. Figure 5-4 shows the successful test, post casualty, of the Stretch Duck 7âs starboard window release mechanism. Shortened Canopy, No Side Curtains Some DUKW operators use shortened canopies, typically with no side curtains. Figure 5-5, a WWII DUKW operated by Chattanooga Ducks, has a shortened canopy so that the aft, raised seating area is not covered. The canopy only uses four vertical supports on each side, spaced well apart. A person could also escape through the front, going around or over the FIGURE 5-2 Canopy on Stretch Duck 7 after casualty. SOURCE: https://www.ntsb.gov/investigations/AccidentReports/Reports/MAR2001. pdf.
CANOPIES AND ESCAPE DURING EMERGENCIES 77 FIGURE 5-3 Side curtain rolled down to protect passengers. SOURCE: https://www.ntsb.gov/investigations/AccidentReports/Reports/MAR2001. pdf. FIGURE 5-4 Side curtain released for emergency exit. SOURCE: https://www.ntsb.gov/investigations/AccidentReports/Reports/MAR2001. pdf.
78 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS windshield. Figure 5-6 shows an Original Wisconsin Ducks DUKW with another version of a shortened canopy, with no side curtains and open at the front and back. This configuration still has relatively closely spaced vertical supports that can impede escape over the side. Shortened canopies with no side curtains may be a challenge for busi- nesses operating in areas that frequently experience cold, breezy, or rainy weather during their operations. Escape Hatch in Canopy An escape hatch in the canopy allows at least some of the passengers to swim or float to the surface without having to leave the vessel over the sides. Designs for escape hatches vary in their length and the means of opening. Boston Ducks, which has a fleet of Truck Ducks, uses a sliding hatch in its canopies. The canopies are constructed of a lightweight reinforced vinyl that is easy to cut. The hatch panel is 7 feet square, located in the stern area, and slides forward (see Figure 5-7). The hatch is normally closed and has a handle with instructions to slide open in case of an emergency (see Figure 5-8). FIGURE 5-5 Chattanooga WWII DUKW with shortened canopy. SOURCE: A. Moyers, Chattanooga Ducks.
CANOPIES AND ESCAPE DURING EMERGENCIES 79 FIGURE 5-6 Original Wisconsin Ducks DUKW with open, reduced-size canopy. SOURCE: T. Graul, committee member. FIGURE 5-7 Stern area slide roof on Boston Duck Tours. SOURCE: T. Cerulle, Boston Duck Tours.
80 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS The hatch is mentioned in the pre-trip safety orientation. Although this hatch provides a means of escaping upward and through the roof during a casualty, it only extends for a limited length of canopy. This escape route is only available to persons who can reach the hatch in time and swim up through it as the vessel is sinking. Boston Ducks has also developed another design, yet to be approved by USCG, that includes two hatches, the hatch in the stern area and a center- line hatch. The hatch at the stern slides aft. The centerline hatch is 11 feet by 4 feet and slides forward (see Figure 5-9). The Original Wisconsin Ducks has developed a removable center sec- tion that extends the full length of the canopy. It is opened in an emergency by pulling downward (see Figures 5-10 and 5-11). FIGURE 5-8 Emergency handle with manual pull for sliding roof, Boston Duck Tours. SOURCE: T. Cerulle, Boston Duck Tours.
CANOPIES AND ESCAPE DURING EMERGENCIES 81 FIGURE 5-9 Slide roof panels with centerline hatch, Boston Duck Tours. SOURCE: T. Cerulle, Boston Duck Tours. FIGURE 5-10 Pull open canopy section, Original Wisconsin Dells. SOURCE: T. Graul, committee member.
82 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS Passenger-Opened Side Windows All Boston Ducks are fitted with side curtains made of a piece of clear plastic for each window frame defined by the vertical supports. The canopy frame and supports are constructed of aluminum, and the supports pro- vide an opening that is 4 feet 6 inches wide and 2 feet 10 inches high. The plastic windows are attached to the canopy frame using hook-and-loop ( Velcro) fasteners and are easily removed or released for over-the-side egress. Figures 5-12 and 5-13 show a Boston Duck side curtain pushed open, like for an escape, and one stowed in rolled up position. No Canopy During Water Operations In Ireland, regulations for amphibious passenger vehicle (APV) operations require operators to remove canopies and passengers to don life jackets for the duration of on-water operations. According to the United Kingdomâs Marine Accident Investigation Branch (MAIB), passengers were willing to wear life jackets as part of the tour.15 15 MAIB, 2014, Very Serious Marine Casualty Report 32/2014, December. https://assets. publishing.service.gov.uk/media/54c1722240f0b6158d00002b/MAIBReport_32-2014.pdf. The committee attempted to contact the operator to gather more information about this opera- tion; however, the operating company is in liquidation. FIGURE 5-11 Pull down canopy section on length of centerline, Original Wisconsin Dells. SOURCE: T. Graul, committee member.
CANOPIES AND ESCAPE DURING EMERGENCIES 83 FIGURE 5-13 Side curtain in rolled up position, Boston Duck Tours. SOURCE: R. Cook, committee member. FIGURE 5-12 Side curtains affixed with Velcro tabs, Boston Duck Tours. SOURCE: R. Cook, committee member.
84 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS The lack of a canopy during water operations may make operating a business in colder, rainy climates more difficult. OTHER CANOPY SOLUTIONS The committee investigated potential solutions that would retain the canopy and side curtains, but still improve the ease of escape. Breakaway or float- away canopies could work in theory, but present difficulties in safe execu- tion. More promising are easy-open canopies and easy-open side curtains. The committee learned that DUKW tour operators are considering some of these solutions with the goal of making canopies less of an impediment to escape. Float-Away Canopy A float-away or breakaway canopy could remove the canopy from block- ing escape upward as the vessel is sinking; however, to be effective, such a canopy would need to be released and shifted away well before the DUKW was fully immersed. In addition, any float-away mechanism would need to be below the canopy itself. If the canopy were the floating part, it would not lift off the vessel until the canopy was immersed, and such a canopy could still potentially trap passengers under water, especially if they are wearing life jackets. The design for such a float-away or breakaway canopy would also need to be able to prevent the canopy from being blown off while driving on land or in squalls on the water. The many difficulties with this concept have prevented it from widespread implementation. Easy-Open Canopy During the sinking of the Stretch Duck 7, some passengers escaped through an opening made when part of the canopy dislodged. Installing rip-away soft canopies, or clamshell hard canopies that open upward during a casualty, would provide a ready means of escape as the vessel sinks. Such a canopy would allow operators to direct passengers to wear life jackets for all waterborne operations or to don them during early phases of an inci- dent. Designs for easy-open canopies should include activation mechanisms that do not require operator actions to open the canopy. Easy-Open Side Curtains Side curtains, if any, need to be opened quickly and fully to facilitate the es- cape of persons wearing bulky life jackets. As the Stretch Duck 7 revealed, even having just two release mechanisms, one for each side curtain, proved
CANOPIES AND ESCAPE DURING EMERGENCIES 85 too much for the crew to execute during the emergency. If the crew member is injured during a casualty, then it is even more likely the side curtains will not be released, trapping the passengers. Passengers should be able to assist or lead with opening side curtains to expedite their escape. Having passen- gers open any side windows themselves is also consistent with the NVIC 1-01 stipulation that the primary means of escape is over the side and that any impediments to passenger escape should be minimized.16 On the Boston Ducks, the window coverings attached via hook-and- loop (Velcro) can be pushed outward and almost completely removed from the frame during emergencies (see Figure 5-12). Individual window cover- ings save the person removing a curtain from having to struggle with a long length of side curtain. However, individual window coverings do require multiple passengersâlikely two for every row of seatsâto have the height and strength to remove the window curtain. If window coverings are just pushed open on the bottom or side, and not removed, the hook-and-loop could reseal itself after an individual escape. The possibility of resealing implies that all passengers would need to be capable of opening a window curtain. In addition, hook-and-loop window attachments must be weak enough for passengers to detach, but strong enough to not blow free when traveling down the road. Easy-open side curtains should be designed so that passengers of a reasonable range of weight, height, and strength can open or remove the window covering nearest them by pushing on the center of the window and easily exit the vessel over the side. Clear visual instructions should be posted on the curtains instructing passengers where and how to open the curtains, if required. SUMMARY The committee agrees with NTSB and USCG that canopies pose a signifi- cant risk to passenger safety when escape during an emergency is necessary. Canopies can be particularly deadly when a DUKW sinks because of flood- ing. Rigorous requirements are appropriate for higher risk operations, as defined in Chapter 8. These requirements would include removing canopies or mandating canopy designs that have been demonstrated to minimize risk while wearing life jackets to the equivalent of no canopy. Canopies on DUKWs that are part of lower risk operations pose less of a risk to passenger safety, but implementing improved designs is still likely to be an advisable safety improvement. Any side curtains should not require crew actions to activate and should be easily openable by a range of passengers, intuitive to use, and labeled with instructions on how to use. 16 Enclosure 1 to NVIC 1-01, section regarding 177.500 - Means of Escape