Returning to the original question:

If you mean everyone boarding through the back door rather than the front door; then yes. Been quite awhile but I've done it a few times. (Explanation given that the jetbridge was not operational). Makes more sense than cancelling, or badly delaying a flight to change gates, even if it means some passengers with ambulatory issues may have to be rebooked. Have also deboarded out the back for the same reason (and once on some kind of test using both doors).

If you mean everyone boarded through the front door BUT starting with those seated in the back and working forward; then the answer is still yes. Twenty-five years ago, during my heavy business travel days, there were only two classes of seats. First loaded. Then coach by group starting from the back forward. AA did it all the time.

But Marketing and Revenue Management got involved. Hold baggage was no longer free, and seat classes started from lower steerage, then coach, super coach, business, and Flagship First. Overlaying it all is AAdvantage status from gold to finally the exalted private tiers that cannot be spoken about. So boarding had to change to something more representative of revenue and frequency. Which makes sense but costs efficiency. Even in the last year or so they "again" beta-tested fast-loading schemes; which all involve some version of sending people to the back sooner so the aisles don't get clogged.

But it is an idea doomed to rejection. Elite boarding groups are earned by frequency or paid for with money, and one of the features promised is boarding order (and implied with it overhead space).

Actually, yes. The end of last year either LAS to PHX or the return. Heavily delayed inbound flight and short turnaround time. The GA said he wanted to board back to front by row number, all through the front door. Said it would be quicker.

If I recall it was something like boarding by the last 5 rows (and first class); then the next 5 rows and so on. Worked fine, no idea if it was quicker though.

I remember many years ago, flying on either SJC-DFW or the nerd bird SJC-AUS. We were delayed significantly, to the point that many people were accommodated on the next scheduled flight, and we were less than half full. GA made an announcement to the effect of "we know how hard you all have worked for your elite status and we really, really appreciate your loyalty but we also know you all just want to get where you are going, so we are just going to board by row!" She then called people in the back 5 rows of the plane first, followed by the next 5 rows, etc until she got to the front. Several people actually thanked her, and I don't recall a single complaint.

+1. Back in the days before the multiple tiers of elite status and fare groups, that's how it was done (1980s and 90s). Many international carriers still do it that way, because it gets the pax on board faster.

The way that the original question was phrased. boarding by the rear doors was what I thought that the OP meant. I was equivocal and I took it to mean exactly that, probably because in Europe it is very much more commonplace then in the USA.

If it meant that the boarding was filling the aircraft from the back to the front then it seems the most sensible way to board Economy. I appreciate being able to board first in F, I used to assume that this was so that you could get a PDB. I now realise that this is just as likely to happen - or that the drink has become a plastic glass of tepid water or OJ when it happens at all. Indeed it is so likely not to happen that we have threads that stretch from here to DFW on the subject. That said the poor FA has to fight down the aisle and you have to manage to keep out of the reach of people's good and chattles being hauled along. However, that is not the original topic. I have no idea what constitutes the different groups - all I know is the line regularly blocks as people stow their stuff after removing their inflight toys.

Yes, I have heard of this. About 30 years ago, this was the norm.

Pre baggage fees days this was typical, but it’s been 20+ years.

I recall an AUS-SJC nerd bird flight in the late 90's, where the GA in AUS said about 3/4 of the plane is elite so we're just going to board by row.

If I'm in F, I don't care if they board F last as long as the FAs keep the overheads clear and hopefully a quick PDB.

I had something similar happen with a SFO-SNA flight (a LONG time ago). SNA has a curfew, the flight was delayed, and if they didn’t board quickly the flight would either be cancelled or diverted to LAX. I don’t recall if they boarded F first, but for Y they boarded back to front, calling two rows at a time. People were pretty motivated to make it work and boarding was very quick.

20-30 years ago that was the norm before airlines began to monetize coach seats and the boarding process. Granted flights didn't tend to be completely full but I remember boarding being far, far less chaotic and usually done within 15-20 minutes.

Less full flights, as you mention, plus fewer seats per plane, plus no fees for checked bags so fewer carryons.