Usable Harness Positions with 3 in 1 Car Seats.


Moderator - CPST Instructor
Usable Harness Positions with 3 in 1 Car Seats.

There are currently a number of 3 in 1 car seats available for purchase. These types of seats are designed to be used rear-facing, forward-facing, and then as a booster. (Note that the harness has to be removed when using these seats in booster mode.)
This article will specifically address the 3 in 1 seats manufactured by Dorel, Cosco, and Safety 1st that have a harness height adjustment system that requires no re-threading of the straps.

These seats are available under a variety of different names:
  • Alpha Omega
  • Alpha Omega Elite
  • Alpha Omega ‘Luxe
  • Eddie Bauer
  • Eddie Bauer Deluxe

This list is not intended to be all inclusive since product lines and names can change periodically. There are also a couple of combination seats that have the same type of harness adjustment, and the same information applies to them as to the 3 in 1 seats. You can tell if your carseat is one described in this article by looking at how the harness height is adjusted.

For simplicity, all 3 in 1 seats will be referred to as the Alpha Omega for the remainder of this article. If your seat’s harness height is adjusted by raising or lowering the headrest, this article applies to your seat regardless of what brand name it is.

Example of an Alpha Omega 3 in 1 car seat:

The Alpha Omega seats are designed with an adjustable headrest to raise or lower the harness height. Depending on whether you have a deluxe model or not, the headrest is adjusted either from the front or the back of the carseat.
*Refer to your owner’s manual for instructions on how to adjust the headrest/harness height for your specific model.

There are 5 height positions for the headrest – the bottom 4 are for use with the harness, and the top position is for use in booster mode only. The top position of the headrest is not reinforced, which is why it cannot be used in harness mode.

Image of embossing on seat indicating “top position booster only”

It is important, with the Alpha Omega carseat, to be aware of what position the headrest is in. As your child grows, you will move the headrest up in order to keep the harness at the correct height:

  • Straps coming from the seat at or below your child’s shoulders if your child is rf’ing

Image from pg 12 of Alpha Omega manual.


  • Straps coming from the seat at or above your child’s shoulders if your child is ff’ing.

Image from pg 12 of Alpha Omega manual.

When using this seat with a ff’ing child, every time the child’s shoulders go above the slots on the headrest, the headrest needs to be moved up. Once the headrest has been moved up to the 2nd highest position, this is the last usable harness height with the Alpha Omega seat. When your child’s shoulders go above the slots with the headrest in the 2nd highest position, the seat has been outgrown in harness mode - even if your child is still under the weight limit.

Image from pg 13 of Alpha Omega manual.

The 2nd highest position of the headrest is what is commonly referred to as the top usable harness position.

There are a few seats made by Dorel, Cosco, and/or Safety 1st which are still 3 in 1 seats, but do not have the headrest issue. If your seat has different sets of slots that you re-thread the harness through as your child grows, then all of the slots are usable with the harness. It is only the seats with the harness height that is adjusted with the headrest that are affected by this limitation.

In summary, if the seat your child is using is an Alpha Omega or similar,

1. Always be aware of what position the headrest is in.
2. Be prepared to transition your child to a different harnessed seat once your child’s shoulders go above the slots with the headrest in the top usable position.
3. If your child is currently using the harness with the headrest in the top position, you must immediately discontinue using the harness and either convert it to booster mode or switch to a different seat.​

Note: Most children are not big enough, old enough, or mature enough to properly use a booster until the age of 5 or 6. It is not within the scope of this article to recommend further seats or tell you if a booster is suitable for your child once the harness of the Alpha Omega has been outgrown. In most cases your child will require another harnessed seat. There are numerous resources on which will assist you in making the decision that will keep your child as safe as possible in the car.
The following article is a good place to start: Ready for a booster?


Moderator - CPST Instructor
Thanks for this article Trudy!

How did I miss it before :confused:

YW. :D

I think it just didn't show under new posts right away because it was really late at night when I submitted it and the news forum titles tend to bump out the title of whatever article was most recently posted. ;)

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