LATCH or Seat Belt, NOT Both2019-10-16T14:30:57+00:00

Lower LATCH Anchors OR Seat Belt, NOT both.

Achieving a Proper Car Seat Installation

It’s a frequently asked question, “Can I use both LATCH and a Seat Belt to install a car seat?”.  The answer is usually NO. 

Using lower LATCH anchors and a seat belt for installation of your child’s 5-point harness restraint is not permitted by most car seat and vehicle manufacturers.

It is a common misconception that using both adds another level of protection.  While there is no evidence showing any extra benefit from using both, there are however, potential dangers.

It is best practice to use your car seat and vehicle safety features in a way that manufacturers intended.  Car seats and seat belt systems are engineered and tested to handle crash forces in a very specific way, so it is always important to follow their instructions accurately when installing your child’s car seat. 

Please note: Very few car seats and vehicle combinations do allow the use of both together, however only when both the car seat and the vehicle indicate that it is safe to do so.

Why we don’t use BOTH

Manufacturers prohibit the use of both systems together mainly because either they did not crash test using both systems, or it was tested and did not meet safety standards.

Manufacturers do not release their internal testing data, therefore we really cannot know for sure the exact reason. Additionally, there is not much data from actual crashes about this type of misuse.

What could happen?

Based on what we already know about crash dynamics and the way restraint systems work, we can speculate some reasons why a seat might fail due to this type of misuse.

  • Putting two installation belts through the same belt path could put additional stress on the car seat from different angles, causing breakage.
  • Using two installation belts could concentrate more crash force on a small area of the car seat.
  • May alter the way the seat is designed to absorb the crash forces and instead transfer more forces to the child. 
  • Both belts overlapping each other might alter the way the webbing is designed to stretch and ride down forces; changing the force required to stretch them, possibly exerting more force than intended on the child.
  • The Lower Anchors might be set in a position relative to the seat belt, that if used at the same time, would cross or overlap and interfere with each other’s proper use.
  • Using both might inadvertently leave the installation too loose, masking an improper install.
  • If both belt webbings have to route through a lock-off, the lock-off may not be able to close, might malfunction, or break precrash.

Which method is safer?

Choose depending on which method allows for the best proper installation. Correctly installing the car seat with LATCH or the seat belt is equally safe; Neither LATCH nor the seat belt is safer.

When it is NOT safe to use LATCH 

  • The lower LATCH anchors cannot be used in the center seating position, unless specifically permitted by both the vehicle and car seat manufacturer. Most often the back seat middle position lacks dedicated lower anchors – this means that a car seat can be installed in the center position using the seat belt method.
  • Check the vehicle and car seat user manuals for the maximum weight capacity of the LATCH system.  Discontinue use of the lower LATCH anchors when the child reaches the weight limit for using lower LATCH anchors.  In many car seat and vehicle combinations this is 65 lbs (weight of child and child restrain combined), though it varies between manufacturers. If unsure, do not use the lower LATCH system when a child weighs 35 lbs or more.

Using the Top Tether with a Seat-Belt Install  

When forward facing, make sure to ALWAYS use the Top Tether regardless of using the lower LATCH or the seat belt for installation method.

Note: Although, technically the top tether strap (part of the LATCH system) falls under the same weight restrictions as the Lower Anchors, it is still advised to use the top tether anchor past the stated weight limit when installing a forward facing seat.  The benefits of the top tether are significant in decreasing forward head excursion in a crash. It is recommended because in the event of a top tether anchor failure it will have by that time served its purpose in a collision.

Using LATCH to install a Belt-Positioning Booster

Many belt positioning boosters can be installed with LATCH when the seat is used in booster mode.  In this scenario, the seat belt is used to restrain the child, while the LATCH system is only restraining the booster seat itself.

H2S Belt or Latch not both

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