Osprey Porter 46 as carry on

I carried on the Porter 46 on Aer Lingus without issue. It’s mostly the handles which make it “over large”. The important thing is to not stuff it full and to cinch everything down. Of course I was flying a different airline than you and this was in the spring, not peak travel season. So if you’re on a packed flight with prickly gate agents you might be required to gate check your bag. You might also check seat guru or similar website to see exactly what sort of aircraft you’re on and whether the overhead bins will accommodate your bag.

Take a look at your bag. You will notice is is soft sided. It is not a rigid frame. The dimensions they give are the maximum. Unless you pack it to the gills you should have no trouble squishing it down to the dimensions required.

There are many people here who use that bag without problems.

I have an Osprey 46 Poret and flown KLM Air France and been fine. Tighten the straps as much as you can, make it look smaller, and they won't bother you. Ive flown many airlines with it and never been stopped. IME, because its soft sided, it appears smaller, and more important, you can shove that bugger in the overhead under most circumstances ;)

Adding: I also carry a Seatosummit stuff able back-pack (or back-sack) which weighs ounces and crushes into your palm, but I pull this out of my Osprey and fill it with everything I will want on board the plane. For the purposes of making my pack look smaller, I do this before I go through security. This makes the weight and size of my Osprey a non-issue, and also makes accessing to the essentials on board the plane easy
https://www.rei.com/product/136763/sea-to-summit-ultra-sil-travel-day-pack?CAWELAID=120217890004913668&CAGPSPN=pla&CAAGID=16061530960&CATCI=pla-70928949520&cm_mmc=PLA_Google%7C404_7638%7C1367630002%7Cnone%7Cde0208bb-1481-4196-be6a-46f4f0787288%7Cpla-70928949520&lsft=cm_mmc:PLA_Google_LIA%7C404_7638%7C1367630002%7Cnone%7Cde0208bb-1481-4196-be6a-46f4f0787288&kclid=de0208bb-1481-4196-be6a-46f4f0787288&gclid=EAIaIQobChMIoLC1wJS84gIVlbfACh0agQqbEAQYASABEgKWJ_D_BwE

If you pack the bag full, especially in the outer pockets, it won't fit in a small overhead bin. When I travelled to Alaska, i put a full length rain jacket in there and i had to take it out for the flight. If you use that pocket for paperwork it is fine. I keep mine under 21 pounds. There was a flight where they were gate checking all roller bags. My bag was bigger than some of those. I went to give my bag to the agent and she said, "No, honey you are fine with the back pack". Then I almost couldn't squeeze my bag into the bin.
It is a great bag.

I bought the Farpoint 40 just to be safe on the smaller planes.

Plenty of room. I always end up packing to the space I have and end up overpacking with a larger bag,

I second Jessica's opinion. My experience is that everyone will have items like a sweater/jacket, guidebooks, passports and travel information folder, tablet, charger, toothbrush, etc. that you will want to access on the flight. Having a small grab bag (or an ultralight Osprey ripstop backpack) within your backpack to pull out before boarding as a "personal item" to have available at your feet will reduce the amount within the Osprey nicely to fit in bins, and it will then go back into the main bag upon arrival for hands-free functioning. This approach keeps me from filling the bag too full and also bringing another separate "personal item."

As one who has always been adherent to the rules regarding baggage (we hate to check) and who just returned from 3 weeks in Italy, I’m changing my tune and weighing in on this side-you’ll very probably be fine. I too perseverate about the odd inch or so. We flew Delta coming and going and Alitalia within. I did not use my favorite bag, a Briggs and Riley international widebody spinner as it was an inch too wide. Did OK with my old but trusty TravelPro but would have liked the former. As I scanned the crowd at boarding there were bags way bigger than mine so the Briggs and Riley would have been fine. Not to say a zealous gate agent could have stopped those. But with a big plane, the urge to board quickly, the growing number of pre boards in wheelchairs, I think this was the last thing on their minds. I think if a bag meets the eyeball test you’ll likely be fine. With Alitalia we met the size requirements but knew we’d be overweight. We dutifully went to the counter and sure enough 2 kg over. So we checked bags. A couple on our tour took the “don’t ask don’t tell” approach for their overweight bags and just marched onto the plane. I looked hard and did not see any scales at the gates. I’m going to play a little more fast and loose with the rules from now on and take my chances, always keeping my meds and other valuables on a small carry on. I’ll let you know how I do.

My Porter 46 goes with me on every trip, and I have never had a problem fitting into luggage sizers or overhead bins on Delta, AirFrance, Alitalia, or Turkish.

Once I had a minor issue coming back from Carnival in Venice on Turkish Airlines. I had a checked bag that contained very little beyond a full Carnival costume -- complete with a hoop skirt and a headdress -- and a Porter 46 that contained a lot camera gear, electronics and just enough clothes and toiletries to get me through a couple of days in Istanbul. I got to the check-in desk at the airport, and the Porter 46 weighed 8.2 kilos, just over the 8 kilo limit for cabin baggage. Eek! I explained that I didn't want to check the electronics, and the attendant smiled and nodded and slapped an "approved for cabin" sticker on the bag. I was good to go.

Of course, two weeks at Carnival was an exceptional circumstance, with a very unique packing list. Ordinarily, I wouldn't be carrying a massive costume or that much camera gear. On other trips, the Osprey Porter 46 has been perfect.