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 Open Letter to the Curriculum Committee: “Tethers Need Special Attention in Next Update"
Dear Members of the National CPS Board Curriculum Committee,
    Thank you for asking the CPS community to provide input as you prepare for the next major standardized CPS curriculum (Curriculum) update. Sorting through all the feedback that was provided by the June 1 due date will be a big job, and we applaud you in that worthwhile effort.
Safe Ride News Publications and SafetyBeltSafe U.S.A. have jointly sent you some detailed edits from specific chapters and pages, but we would additionally like to comment on the important subject of tethering for high-weight-harness (HWH) CRs in more general terms. These comments are submitted in the interest of helping to provide CPSTs with a stronger foundation for understanding this important subject, especially regarding the following two challenges that we see facing CPSTs today.
The first challenge is to get more people to use tethers. With studies showing that tether use has been inexplicably stagnant at less than 50 percent for the last several years, this effort should be an urgent public safety priority. The fundamental messaging for this effort must be present in the Curriculum, so we hope this content will be made more clear, robust, and prominent in the upcoming revision, and we have provided you with specific suggestions.
The second challenge is understanding and communicating vehicle LATCH anchor weight limits. This issue is of special concern with regard to tether anchors since, unlike lower anchors (for which seat belts are Plan B), there usually isn’t a viable alternative to functionally substitute for an unusable tether. The alternatives that have been devised for a few products (2011 LATCH Manual, p. 71) are extremely limited for the general public.
The October 2010 Curriculum revision added an acknowledgement that confusing situations exist regarding anchor limits, such as when the CR and vehicle manufacturers either disagree about tether anchor weight limits or give no guidance. It also tells CPSTs to assume a 40-pound anchor limit in these situations.
This is undoubtedly a complex issue, but we must express concern that the Curriculum currently tells CPSTs to specify a low 40-pound weight limit for tether use in the absence of guidance from the vehicle manufacturers and also without further explanation from the National CPS Board (NCPSB). Therefore, we urge the NCPSB, NHTSA, and their expert biomechanics consultants to reexamine this situation for the forthcoming Curriculum update. In particular, we’d like to note the following:
• The urgency of improving the tether usage rate, especially at higher child weights, increased with the publication of the April 2011 AAP revised policy statement regarding child passengers. The new statement includes strong language to encourage harness use as long as possible, noting that best practice may mean that children as old at 8 may still ride this way. Though we are hopeful that more children will ride in harnesses longer, it is an unfortunate fact that the limitations of available testing technology (especially dummies) inhibits the current ability to test in any meaningful way the potential head excursion of children over 50 pounds in HWH CRs. The laws of physics suggest, however, that the taller and heavier a child is, the more head excursion will occur in a crash, and the more important a tether would be to prevent head injury.
• Much has been made of the risk of tether anchor failure, but we are unaware of any real-life occurrence. Therefore, we wonder if anyone has examined the precise nature and seriousness of this potential risk. It has been conjectured that TA hardware, if detached, might become a projectile, or that there might be an abrupt failure leading to sudden forward excursion. But do we truly understand the failure mechanism and the degree of injury it could inflict? Analysis of this situation should be based on more than conjecture; it is fundamentally important to scientifically determine the true risk of anchor failure in order to be able to properly assess the risk/reward trade-off of using a tether. These are not easy questions to answer, but we call on the curriculum committee to use its clout and take this opportunity to pursue this issue.
• We request that the Curriculum include some explanation regarding how a default anchor limit has been identified, perhaps as an appendix. Relevant information that SRN Publications has gathered is available in the “Perspective” section of the 2011 LATCH Manual (Chapter 5), but it would be helpful if the NCPSB would explain how this data is analyzed from the point of view of the manufacturers, NHTSA, and other members of the board.   Since it is well known that this subject is confusing, it seems unlikely that CPSTs will stop considering this a gray area until the source of these conclusions is illuminated.
The bottom line is that tether use should be a priority, following manufacturer instructions—and advice to NOT use a tether should be given only when solid evidence shows that this is absolutely necessary. Therefore, we ask you to question the apparent current assumption that a 40-pound anchor-weight limit is conservative and to reexamine what is considered “playing it safe.”
Real-world evidence shows that excessive head excursion can cause head injury and that tether use significantly reduces head excursion. These known facts must be weighed appropriately against the uncertainty of anchor failure and potential injury, and efforts should be made to clarify these unknowns. Until these factors are better understood and explained to the CPS community, it seems very risky to tell a CPST to discourage tether use when the manufacturers have not specifically provided directions to do so, and we ask: might the truly “conservative” advice actually be to use the tether?
We respect the NCPSB and the importance of the Curriculum content, so we are requesting that the committee take on this important issue as a Curriculum update priority. Though we acknowledge that what we propose may require significant effort, we hope you will agree that the urgency of the situation warrants the undertaking.
©Safe Ride News May/June 2011

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