Health Information and Tools > Health A-Z >  Child Car Seats: The Tether Strap and Universal Anchorage System (UAS)
Facebook Tweet Share

Main Content

Child Car Seats

The Tether Strap and Universal Anchorage System (UAS)

​​​​​​​​​​​​When used correctly, car seats and booster seats save lives ​and reduce injuries. Children can get hurt if their car seats or booster seats are not used properly. Here are some tips on how to use the UAS and/or tether strap to secure a car seat in your vehicle.

Tether Strap

Once a car seat is turned forward-facing, it must be held in place with both a tether strap and the seat belt or universal anchorage system (UAS). The tether strap is on the back of the car seat. It must be hooked to a tether anchor in the vehicle. If a tether strap isn’t used, your child is more likely to be hurt. Their head will move dangerously forward in a crash. It is the law in Alberta that a tether strap must be used for all forward-facing safety seats.

Tether Anchors

The vehicle manufacturer decides where to put the tether anchors in a car, truck, or van. They may put them:

  • on the shelf in front of the rear window of a car
  • on the floor of a van, station wagon, or hatchback
  • under the rear window or on the floor of a pick-up truck
  • on the back or bottom of a vehicle seat

Where the tether is in your vehicle also depends on the age and type of your vehicle:

  • Every car made after January 1989 must have tether anchor locations behind the back seats. You may still need to have a tether anchor installed. Read your owner's manual or ask the vehicle dealer for help.
  • Every car, light truck, van, or sport utility vehicle made after September 2000 will have user-ready tether anchors. These newer tether anchors are easy to find and use. Read your owner's manual to find out where the tether anchors are.

User-ready tether anchors may be marked with this symbol:

The tether strap must be tight. It may need to doubled back to prevent it from slipping or coming undone.

Check the instructions for your car seat. Never fasten more than one car seat to an anchor.

​Universal Anchorage System (UAS)

As of September 2002, all new cars, vans, light trucks, and sport utility vehicles sold in Canada have UAS anchors for at least 2 of the back seats. The UAS anchors are found between the back of the seat and the seat cushion. All new car seats have a UAS belt.

Using the UAS is not any safer than using the seat belt. It is your choice and should be based on whichever you find easier to use correctly. Do not use both the UAS and the seat belt​ with the tether strap to install your car seat. Use one or the other with the tether strap. However, if you’re using the UAS and tether strap, once your child reaches 18 kg (40 lb.), check your vehicle and the car seat manufacturer’s instructions for guidelines about the maximum weight allowed for the UAS. If UAS guidelines aren’t given in your vehicle or the car seat manufacturer’s instructions, use the UAS and seat belt and tether strap to install your car seat only after your child weighs 18 kg (40 lb.).

Seats with UAS may be marked with this symbol:

When using the UAS for your car seat:

  1. Read your vehicle owner's manual to find the UAS anchors.
  2. Route the UAS belt through the belt path on the car seat.
  3. Connect the hooks of the UAS belt on your car seat to the UAS anchors.
  4. Tighten the UAS belt following your car seat instruction manual.
  5. For forward-facing car seats, attach the tether strap to the tether anchor and tighten.

The car seat should move less than 2.5 cm (1 inch) in any direction.

​UAS and the Centre Back Seat

Your owner's manual will tell you if your vehicle has UAS anchors for the centre back seat. If the centre seat does not have UAS locations, the seat belt can be used to secure the car seat.


All car seats are safest in the back seat.

Read your car seat or booster seat instruction book and your vehicle owner’s manual to make sure you are using the seat properly. Make every ride a safe ride for everyone.

If you still have questions call Health Link at 811.​​​​​​​​

Current as of: October 2, 2019

Author: Provincial Injury Prevention, Alberta Health Services