weather, airport traffic control, some tech issues (though not all).

But a lot is within their control. Inefficient boarding processes. Lack of amenities (for all passengers). Nickeling and diming on baggage fees and seat selection. Etc etc.

I've decided if I was the CEO of a major US carrier - say Delta - I'd do the following:

-offer a full meal on any flight over 2.5 hours to all passenger classes. I realize that could be a bit tough on narrow body aircraft where the availability of lavatories is minimal, but there are ways around it. I'd offer drinks and snacks as passengers sit.

-load the aircraft from back to front, so the drinks can snacks can be given in a similar back to front way that doesn't obstruct boarding.

-enforce carry-on sizes, and check AT THE BOARDING DOOR OF THE PLANE any that don't meet size requirements. Don't even let them on the plane. And I'd could do that because

-passengers get two checked bags free. So if the passenger hasn't already checked bags it's no cost, and if they had checked bags they would've had to stop at the bag counter and a ticketing agent there would already have pointed out to the passenger that their carry on would be too big and have to be checked. So by being consistent, people quickly learn there are no exceptions and they bring an appropriate sized carry-on or they check it.

-board by row number, back to front. Scrap status WRT boarding. You don't need to be on first if you sit at the front of the plane just so people can see you as they walk past you. Reset the expectation. Let status determine where you sit but not when. No 1st class then business then aisles first, then windows then middle seats. Back to front, with the possibility to try and alternative scenario like this for a plane with 40 rows (which are correctly numbered sequentially): rows 38-40 and 15-16, then 34-37 and 13-14, then 30-33 and 11-12, then 26-29 and 9-10, then 23-25 and 7-8, then 20-22 and 5-6, then 17-19 and 1-4. More in the back with a few in-between who seat while the back loads, then the next group and so forth. By the time rows 17-19 are loading, preflight snack and drink service is already done for the back half of the flight, then crews from both front and rear finish up.

-make inflight wifi available free to all customers.

I realize all of the above would not be without a cost. But for an extra $20 per flight, a meal, wifi, and snacks - along with better systems and processes - would make the flying experience much better. A $390 RT fare vs $370 is minimal if you know you're going to have a decent meal and wifi.

Discount carriers wouldn't do this. But United, Delta American, etc would and should. The first one to do so would have a huge leg up. You don't have to be Emirates level, just be better.

I've had lots of other thoughts WRT ground ups and gate processes as well, but this post is already too long.