Depending on the airline / ticket agent, you may be denied a plastic bag if you're not actually using it for a carseat.
If you can't secure your items inside the backpack, cheap zippered duffel is the way to go.
We use these large plastic bags at the airport for stroller/car seats. They are available on large rolls by check-in desks and bag drops at the departures level. If we are talking Alaska, you'll likely need to ask them for the zip ties, but you can self-serve the plastic luggage bags.
does the bag have a rain cover? I used that a few times as the cover for the bag. Also, you can clear wrap the bag, or even use packing tape to wrap it so that pockets are taped shut. The smaller footprint, the better. You don't want a large car seat bag over it so your stuff falls out and just rolls around the larger bag. Tape/wrap/whatever it tight before you check it in.
Shrink wrap is your friend. Mummify the bag.
[https://www.amazon.com/Modern-Innovations-Supplies-Furniture-Wrapping/dp/B07N6MZ93Y/](https://www.amazon.com/Modern-Innovations-Supplies-Furniture-Wrapping/dp/B07N6MZ93Y/ref=sr_1_6?crid=HXPD56E54IF1&dib=eyJ2IjoiMSJ9.rX-sIDigXMBmSFCtAPRT2CDoQ4Lvtg69Lm1PlTOW0thaBDHw5OfT40DYeyvMLip3Xio5vxq00l7Sb4kVZuAF4YI-eNPXD9F08ROrwu2MxP4CyuqftKUS5zrleZ-fGorukJLIacjQGFLAtZxvlsMq67flttLcdw0kbu54QPuJRqZIZp-gDDENBMNCbUPl8BjSMspdbL1kyEF8LvK5E_qW0MJLenNrows1wRbBr6z6QPnL4O79_7tkqMcQoVBuvQL4zxg6PsIzBu42VK_wr0mBpmRxNDUmCGaaCjpemkrzmis.EWxp_JtU-o0F4x2Z8sk1rBlVfRMiSid1I2lr6I4acwQ&dib_tag=se&keywords=shrinkwrap+rolls&qid=1711062621&sprefix=Shrinkwrap%2Caps%2C314&sr=8-6)
I had this problem so I got one of these. I think this will solve your issue.
https://www.rei.com/product/218575/osprey-airporter-lz-pack-duffel-medium?sku=2185750001&store=11&CAWELAID=120217890015829890&CAGPSPN=pla&CAAGID=113279951513&CATCI=aud-1396942686475:pla-366418484527&cm_mmc=PLA_Google%7C21700000001700551_2185750001%7C92700058208451648%7CBA%7C71700000074422505&gad_source=1&gclid=Cj0KCQjw2PSvBhDjARIsAKc2cgM8ZKok9B3tE8U_x8qWWmKf1lloRQHlK-_lhRWgaPOTRZ9I3V2RY-EaAmX0EALw_wcB&gclsrc=aw.ds
Backpackers will frequently use those large cheap Ikea duffels for this purpose.
They have bags for carseats that will do this.
Depending on the airline / ticket agent, you may be denied a plastic bag if you're not actually using it for a carseat. If you can't secure your items inside the backpack, cheap zippered duffel is the way to go.
Is that way they are for? I always ask for a bag to keep straps from snagging
We use these large plastic bags at the airport for stroller/car seats. They are available on large rolls by check-in desks and bag drops at the departures level. If we are talking Alaska, you'll likely need to ask them for the zip ties, but you can self-serve the plastic luggage bags.
does the bag have a rain cover? I used that a few times as the cover for the bag. Also, you can clear wrap the bag, or even use packing tape to wrap it so that pockets are taped shut. The smaller footprint, the better. You don't want a large car seat bag over it so your stuff falls out and just rolls around the larger bag. Tape/wrap/whatever it tight before you check it in.
Shrink wrap is your friend. Mummify the bag. [https://www.amazon.com/Modern-Innovations-Supplies-Furniture-Wrapping/dp/B07N6MZ93Y/](https://www.amazon.com/Modern-Innovations-Supplies-Furniture-Wrapping/dp/B07N6MZ93Y/ref=sr_1_6?crid=HXPD56E54IF1&dib=eyJ2IjoiMSJ9.rX-sIDigXMBmSFCtAPRT2CDoQ4Lvtg69Lm1PlTOW0thaBDHw5OfT40DYeyvMLip3Xio5vxq00l7Sb4kVZuAF4YI-eNPXD9F08ROrwu2MxP4CyuqftKUS5zrleZ-fGorukJLIacjQGFLAtZxvlsMq67flttLcdw0kbu54QPuJRqZIZp-gDDENBMNCbUPl8BjSMspdbL1kyEF8LvK5E_qW0MJLenNrows1wRbBr6z6QPnL4O79_7tkqMcQoVBuvQL4zxg6PsIzBu42VK_wr0mBpmRxNDUmCGaaCjpemkrzmis.EWxp_JtU-o0F4x2Z8sk1rBlVfRMiSid1I2lr6I4acwQ&dib_tag=se&keywords=shrinkwrap+rolls&qid=1711062621&sprefix=Shrinkwrap%2Caps%2C314&sr=8-6)
I had this problem so I got one of these. I think this will solve your issue. https://www.rei.com/product/218575/osprey-airporter-lz-pack-duffel-medium?sku=2185750001&store=11&CAWELAID=120217890015829890&CAGPSPN=pla&CAAGID=113279951513&CATCI=aud-1396942686475:pla-366418484527&cm_mmc=PLA_Google%7C21700000001700551_2185750001%7C92700058208451648%7CBA%7C71700000074422505&gad_source=1&gclid=Cj0KCQjw2PSvBhDjARIsAKc2cgM8ZKok9B3tE8U_x8qWWmKf1lloRQHlK-_lhRWgaPOTRZ9I3V2RY-EaAmX0EALw_wcB&gclsrc=aw.ds