Airbag surrounding seatback of vehicle seat

1. An assembly comprising:

a roof rail;

a vehicle seat having a seatback, the seatback having a top end;

a first airbag and a second airbag each inflatable to an inflated position;

the first airbag supported by the roof rail vehicle-outboard of the vehicle seat, the first airbag being inflatable vehicle-inboard from the roof rail in a cross-vehicle direction above the top end of the seatback, the first airbag in the inflated position extending downwardly from above the top end of the seatback to a bottom end of the first airbag, the bottom end of the first airbag being below the top end of the seatback in the inflated position;

the second airbag supported by the roof rail vehicle-outboard of the vehicle seat, the second airbag being inflatable downwardly from the roof rail to a distal end adjacent the vehicle seat below the top end of the seatback in the inflated position;

the first airbag surrounding the seatback when the first airbag is in the inflated position;

a first tether elongated from the distal end to the bottom end in the cross-vehicle direction seat-forward of the seatback; and

a second tether elongated from the distal end to the bottom end in the cross-vehicle direction seat-rearward of the seatback, the seatback being between the first tether and the second tether.

2. The assembly of claim 1 , wherein an occupant seating area is between the first tether and the seatback.

3. The assembly of claim 1 , further comprising a vehicle door adjacent the vehicle seat, the second airbag being inflatable between the vehicle door and the vehicle seat.

4. The assembly of claim 1 , wherein the second airbag is vehicle-outboard of the first airbag in the inflated position.

5. The assembly of claim 1 , further comprising an inflator fluidly coupled to the first airbag and the second airbag.

6. The assembly of claim 1 , further comprising a roof supported by the roof rail, the first airbag being between the seatback and the roof in the inflated position.

7. The assembly of claim 6 , wherein the seatback defines an occupant seating area, the first airbag being between the occupant seating area and the roof.

8. The assembly of claim 1 , wherein the seatback defines an occupant seating area, the first airbag surrounding the occupant seating area in the inflated position.

9. The assembly of claim 8 , wherein the occupant seating area is between the first airbag and the seatback when the first airbag is in the inflated position.

10. The assembly of claim 8 , wherein the seatback is between the occupant seating area and the first airbag.

11. The assembly of claim 1 , wherein the first airbag abuts the seatback in the inflated position.

12. The assembly of claim 1 , further comprising a second vehicle seat, the first airbag being between the vehicle seat and the second vehicle seat in the inflated position.

13. The assembly of claim 1 , wherein:

the first airbag includes a vehicle-forward portion, a vehicle-rearward portion spaced from the vehicle-forward portion along a vehicle-longitudinal axis, an inboard-side portion spaced from the roof rail in the cross-vehicle direction, and a seat-upward portion positioned above the top end of the seatback;

the vehicle-forward portion and the vehicle-rearward portion being elongated in the cross-vehicle direction, the seatback being vehicle-rearward of the vehicle-forward portion and vehicle-forward of the vehicle-rearward portion;

the inboard-side portion extending along the vehicle-longitudinal axis from the vehicle-forward portion to the vehicle-rearward portion; and

the seat-upward portion extending along the cross-vehicle direction from the roof rail to the inboard-side portion.

14. The assembly of claim 1 , wherein the seatback defines an occupant seating area between the first tether and the second tether.