American recently started taking delivery of its latest batch of Boeing 787-9s. These are exciting for the airline and for passengers, as they’re premium heavy jets, with new interiors. What’s less exciting is the recurring maintenance issue that one of these jets seems to be having.
In this post:
The short, cursed life of American’s N846AN
The Boeing 787-9 with the registration code N846AN is brand new, and was delivered to American on April 29, 2025, flying from Everett (PAE) to Dallas (DFW). On June 4, 2025, the plane was supposed to be ferried to Chicago (ORD), with flight number AA9783, in order to enter commercial service.
However, the plane encountered a maintenance issue, and had to return to Dallas, where it landed a little under an hour after it took off.
The next day, on June 5, 2025, the plane finally managed to position to Chicago.
Then on June 6, 2025, the plane was supposed to make its commercial debut, flying to Los Angeles (LAX) and back, operating as AA2012 and AA2321. That rotation ended up getting canceled altogether, again, due to maintenance issues.
The next day, the plane was scheduled to operate the exact same rotation. Fortunately this time around, things worked out a little better, with an emphasis on the “little better” part.
The plane managed to operate the outbound from Chicago to Los Angeles, with a delay of just over two hours. Funny enough, that delay was due to crew availability, rather than due to a maintenance issue. So that was the commercial inaugural flight for the jet.
Yay, does that mean the plane’s maintenance issues were fixed? Well, not so fast. The plane was supposed to have a quick turnaround in Los Angeles, with under 90 minutes on the ground. Instead, the flight that was supposed to depart at 1PM on June 7 has been rescheduled for 9PM on June 8, representing a 32-hour delay, and that’s best case scenario.
So yeah, while the plane was supposed to have operated four passenger flights as of now, in reality, it has operated a single flight. That’s not so good!
Is American’s brand new Boeing 787 a lemon, or…?
Clearly this brand new Boeing 787 has some problems. I’ve heard different theories as to what exactly the problem is, ranging from issues with one of the engines, to issues with one of the doors, so I can’t speak authoritatively to what’s going on.
As @xJonNYC notes, it seems to be unknown whether the current maintenance issues fit into the category of being “growing pains,” vs. there being some bigger issue with the jet.
Of course one would hope that brand new planes are delivered in perfect condition, but there are sometimes mistakes during the manufacturing process (especially with Boeing). Again, I’m not saying that is the case, but the fact that American keeps trying to fly the plane, only for it to then cause huge delays, suggests some issue keeps happening over and over.
I’m going to be tracking this new jet with great interest over the coming days, to see if American tries to keep the plane in commercial service, or if it eventually ends up back in the main maintenance facility in Dallas, or ends up being flown back to Boeing.
Bottom line
American’s brand new Boeing 787-9 with the registration code N846AN is having some recurring maintenance issues. The plane had to divert on its repositioning flight to Chicago, and of the four scheduled commercial flights, two have been canceled, and one has been delayed by at least 32 hours.
It’ll be interesting to see just how serious the issues with this plane are, and if it’ll eventually be taken out of service for some more serious maintenance work.
What do you make of the issues with this new 787-9?
I see no where you exhibit credentials which give you an opinion that has any credibility. You take cheap shots at an aircraft flying all over the world every day. A great dispatch and safety record. Most importantly operates more efficiently than any of your bucket bolts Airbuses.
Most of you are Boeing haters buttt many if not all the problems seem to be with the engines.
These planes were built under the most corrupt and irresponsible executive managers. Dead whistleblowers tried but died.
Building planes is a large complicated process and Requires excellent quality controls and executive management needs - Consientiousness.
The new guy needs a miracle to turn around Boeing.
LOL
Boeing needs a miracle?
THEY GOT ONE!
After the death of hundreds of passengers, their criminal charges were dropped
after losing all that money on the Air Force One contract, that got the new 6 gen fighter to build
They are going to be fine
Hate Boeing much?
One of my family members was an engneer with Swissair (SR) in the 1970s and 80s. Whenever an SR-plane was assembled by Douglas or Boeing, he was sent to Longbeach or Everett, to supervise the work. He was part of a larger team of SR engineers doing this work and at least two of them had to present at any given moment. We always questioned whether such close supervision was really necessary, but he assured us that it was ...
To John Barton well said you are 100% correct.
first, it was McDonnell Douglas and second, McD D waited too long to develop any new aircraft so had no choice but to keep rehashing old designs which weren't as good as the original ideas (see L1011 vs. DC10/MD11)
There was a joke for a long time that DL's DC 9 family aircraft (now just the 717) would ferry the crew home from the desert as the last Boeing is retired but I think that...
first, it was McDonnell Douglas and second, McD D waited too long to develop any new aircraft so had no choice but to keep rehashing old designs which weren't as good as the original ideas (see L1011 vs. DC10/MD11)
There was a joke for a long time that DL's DC 9 family aircraft (now just the 717) would ferry the crew home from the desert as the last Boeing is retired but I think that joke will fall early next decade.
as to the comment above, airlines regularly have mechanics at their suppliers' sites including manufacturers and MROs.
It has as much to do with clarifying requirements as "supervising" anything.
No two airplanes are exactly the same.
It depends on what parts in question are having issues. If the issue is with the engine, it’s GE’s problem because GE designed and made the engines. Now as for the doors, that depends. If it’s the business class doors or lavatory doors having problems, it’s on Collins Aerospace, designer and maker of business class seats and lavatories. If it’s one of the 8 pressurization doors, then it’s Boeing.
Its Boeing's problem regardless of part sourcing - either a specification or QA ball dropped
So then by that reasoning, Airbus must be held responsible for QF32, AF66, MU721, LX1885, AC609 issues with PW1000G engines and Swiss having trouble with first class seats that will be installed on A330s
Air Nz is having similar problems with 787-9 planes , high maintenance
You need to get your facts on straight. Boring merge/ bought out MD, vanished all it's commercial aircraft, except the 717, formerly known as the MD 90. Kept only the military contracts and got room off most white and blue collar workers. McDonnell Douglas doesn't exist anymore....
There was a time in the 1990s when the BA fleet was almost exclusively Boeing?
BA had the world's largest fleet of 747s, plus a plethora of 767s and 757s.
Sometime in the 1990s, the short haul fleet transitioned from 737s to the A320 family.
So the non-boeing aircraft were primarily Embraers, the BAe 146 etc smaller aircraft.
Well this is a pleasant thread of comments.
One observation ...
I wouldn't bet against AeroB13a being British.
But I certainly wouldn't bet on AeroB13a being British.
The choice of phrasing is rather unusual in places.
@Ben, when you can report what the actual problem was please do a hit piece. Until then you’re grasping at your pearls. Clickbait.
I agree. It must be a slow day in Miami. The post would be better if it was linked to Trump or Delta for comments.
The only thing that can resolve an issue like this is more tariffs!
or more Cowbell
I've got news for you, virtually every large airliner in service has some sort of current maintenance issue. Redundancy allows them to operate with certain inoperative components but there is a list of items that cannot be deferred and a problem with one of them will ground the flight. It could be something as simple as an emergency exit sign or as vital as a flight control computer. Maintenance on these beasts, starting from the...
I've got news for you, virtually every large airliner in service has some sort of current maintenance issue. Redundancy allows them to operate with certain inoperative components but there is a list of items that cannot be deferred and a problem with one of them will ground the flight. It could be something as simple as an emergency exit sign or as vital as a flight control computer. Maintenance on these beasts, starting from the day it rolls off the assembly line, is a 24 hours a day, 7 days a week job. That's how they work.
Boeing has lost ALL credibility. And no surprise this is all happening to such a WONDERFUL airline such as AA.
PREACH !
This comment section is a joke.
Let’s not pretend that this didn’t happen 6 months ago:
When Malaysian had to GROUND 2 brand new A330neos because of sh*t quality.
https://www.airlineratings.com/articles/malaysia-airlines-new-a330-grounded-airbus-and-rolls-royce-to-blame
The N-number on an aircraft ("N-number" is specific to refer to aircraft registered in the United States)
Registrations aren't referred to as a "code".
Every country has their own designated registry protocols. Canada, they begin with a 'C' hyphen, then letters. The UK? A "G" hyphen.
You can Google specific country ICAO aviation registry specifics.
I might take a decade to take the McDD culture out of Boeing - if it even happens at all.
Ummm... it has been almost 30 years since the merger...
Maybe so. But the management style, that came with merger is only now being purged.
Look at it another way, the plane is fine but it's the same old FA's.
Maybe so. But the management style, that came with merger is only now being purged.
Look at it another way, the plane is fine but it's the same old FA's.
The first 747 commercial flight was delayed until the next day (well, like 6-7 hours) because the airplane crapped an engine.
True, I do remember reading about this. But upon retrospection, that was an inaugural flight for an entirely revolutionary, 'brand new' aircraft..
How long has the 787 been in production / service ?
So maybe not quite the perfect comparison... ?
If it's Boeing, you're not going.
We sure know how to build them!
Since Boeing bought McDoald Douglas the quality in Boeing aircraft have taken a nose dive. The excutives from McDonald Douglas have only focused on on the stock returns! The engineers from Boeing have been pushed back so that the stock returns are higher and the quality of the aircraft have fallen!
AA will fly the aircraft when is it ready. I think all the comments about Boeing are ridiculous, it's not like Airbus aircraft are perfect. Plenty of 320/321 NEOS are grounded around the world with problems.
Nothing to see here, just a slow news day.
You might think that Dk, others do not need to comment or state the obvious …. :-(
The A320/321 neos and you forgot A220 are grounded because of engine problems. And guess who is in charge...... Pratt and Whitney! BOOM
What maintenance? It was newly delivered. Why does it need maintenance?
Your whole thing with Boeing is that this one new plane has some issues. Have you ever reported on other companies new planes and see if any of them had any issues?
It's the same thing with Tesla. Find any negative issue and report it.
@Ron
Apparently, according to AeroB13a the BA apologist and Boeing hater (yet BA flies some of the most Boeing widebodies), whatever Boeing does is wrong and their planes are trash. So unfortunately, your opinion won't be valid.
Boeing and Tesla serve an important role in the US industry/economy, yet people bash them for the tiniest reason they can think about while complaining about the economy getting f*cked.
The power of brainwashing.
Mason old dear, why ever would one need to state that anyone is a “Boeing hater”? Every thinking aviator on the planet knows the truth, seemingly it is only you who has to keep “Apologising” for the current Boeing failures.
Apparently Mason, it is also you who is swallowing the Boeing propaganda and failure to see the Tesla effect upon the U.S. economy. Will we observe a couple of Tesla’s on your driveway sunshine?
And yet Boeing has 'murdered' around 1000 pax so far, at least. Counting the 2 recent MAX crashes, of course but also going a bit farther back with their faulty repair job on that JAL 747
aft pressure bulkhead eventually resulting in a horrific, torturous disaster in Japan claiming hundreds of lives as well .... But, oh well, that's just the ' cost ' of business....
I remember when wrenches and other tools were found inside semi built fuselages. I just think you pray those days and those mechanics are long gone! Yet…. The beat goes on, evidently
More AA incompetence
Not Boeing perhaps?
Probably both ... A 'match' made in hell ! ... lol
Seriously, AA's recent 'hiccups' in NAP (ops) & DEN (737 MX) should get the (IN)attention of the FAA ....
What Max in DEN?
The AA 737 wasn't a MAX but a -800. The 'MX' refers to the 'maintenance' abbreviation...Seems like some engine part(s) were installed incorrectly, resulting in a fuel leaf & fire ... Sorry for the confusion...
Wow that is interesting. I’ve never thought of lemon planes but I’m sure it could happen. Will be interesting to observe
Remember the Alaska 737 Max with the door plug that fell off? Boeing bought that plane back from AS.
Hey All .. Have you ever looked at all the wiring, plumbing, sheetmetal, avionics in one of these babies? I’m surprised , pleasantly, that any brand new, man-made machine as complicated as these, actually work as well as they do. We all want perfect I understand. But sometimes, even with the best technology, crazy things still happen.
This whole episode is just typical of AA. Enter thevplane into season soon as possible. No need for a shake down flight. MOST embarrassing is NO CREW FOR THE INAUGURAL FLIGHT
Something tells me their is more underlying here than AA forgot to schedule crew. Did an assigned crewmember call out sick perhaps?
I flew an Austrian 787 from Vienna to Frankfurt. Brand new. You could almost smell the paint. They flew similar routes for a full month. For the benefit of the FA's. Full business meals well.
That's how real airline works. Not AA.
In AA's defense, that was the purpose of the ORD-LAX-ORD flights staff familiarization flights before the aircraft is assigned its ORD-LHR-ORE sked.
Of course, I can't comment on the composition or quality of the gastronomy & beverages where I'm sure Austrian excels !
What happened to your robots/soa computers. You still have to remember your issues before firing your experienced staff. This includes the pilots.... sorry, thank you. darius sharifzade
The plane needs to be looked at by maintenance people in Naples, Italy right away!
LMAO
Hey ... those poor folks in NAP had nuttin' to do with that AA little gaffe/ovahsight ! But they had
to bear the brunt of the incident in addition to FCO staff.
Ya get credit for tryin', but just substitute AA MX & Dispatch and you have a winner !
Alright! Let’s play a game! Is it…
A. The seats
B. Something with the specific aeroplane
Vote while there’s still democracy!
Just another anti-Boeing click bait article. It’s common to work out new aircraft kinks. Airbus and Boeing.
Should have ordered an Airbus 350-900
Or not retired their a330s and 767s.
So what was the "maintenance issue" ???
This may be common with mass produced commercial aircraft, but with modern tracking tools we have just become more aware of it.
I was supposed to be on the LAX-ORD flight today to try out the new flagship suite. Got an email this morning saying they "rebooked" my flight which now shows a block one 787-8 operating the flight instead. Was pretty disappointed but wasn't surprised as I was also tracking this tail number and noticed a lot of delays and cancellations associated with it. Hope to eventually get to try this product out and hopefully they fix whatever is wrong with N846AN as well.
Please excuse my ignorance, but what does the term ' block one ' refer to in your above post ?
thx !
Block one refers to the first batch of 787-8s AA received (delivered between 2015 and 2017)- these have the Zodiac Concept D - forward/backward facing seats.
Was this jet made in South Carolina?
Yes
" I’ve heard different theories as to what exactly the problem is, ranging from issues with one of the engines, to issues with one of the doors, so I can’t speak authoritatively to what’s going on."
A true statement.
If you look at the photos from media day the business class seats look heavy while the economy seats look wafer thin like fold up chairs with padding . Can the weight and balance of a plane change inflight after fuel burn ?
The 777 767 757 747 737NG* are all great aircraft.The 787 is a piece of junk.The airbus is a piece if garbage compared to them and is truly a throwaway airplane Airbus=Scarebus.Hopefully boeing comes back with the 797 soon because it's looking bad...
One has been accused of being one of Ben’s, “Army of the ignorant”. That may have been true as far as the commercial airline ‘business’ is concerned. However, since reading Ben’s blog my horizons have been broadened not only by the editorial content, but the sensible comments too. I am a grateful recipient, thank you.
My knowledge of the Boeing offerings are mainly military based, both rotary and fixed wing. One’s experience has been...
One has been accused of being one of Ben’s, “Army of the ignorant”. That may have been true as far as the commercial airline ‘business’ is concerned. However, since reading Ben’s blog my horizons have been broadened not only by the editorial content, but the sensible comments too. I am a grateful recipient, thank you.
My knowledge of the Boeing offerings are mainly military based, both rotary and fixed wing. One’s experience has been long, extensive and mainly positive.
As a commercial aircraft passenger, I have been fortunate enough to have experienced hundreds of hours in both Airbus and Boeing aircraft. Without a shadow of a doubt, I would always choose an Airbus ride over a Boeing flight. The A350 and A380 being my go to aircraft of choice.
I will never set foot inside a 787-9, 777X or that matter the very suspect Max thingy. That said, I still have two more missions to complete this month for my masters, thankfully both are scheduled to be in Airbus aircraft at the moment. As following those flights I will be the one paying for my rides, only Airbus flying airlines will enjoy my patronage.
I have flown several flights on the 789, including an ORD-LHR round-trip, and one MAX flight.
The 789 is better than the 773 and the 763, while the MAX seemed no different than the 737NG.
A friend of mine has flown with a major carrier for over 30 years, avoiding McDonnell Douglas and Airbus (or as he says, Scarebus) like the plague.
Too many of his fellow pilots from his airline complain of the Airbuses...
I have flown several flights on the 789, including an ORD-LHR round-trip, and one MAX flight.
The 789 is better than the 773 and the 763, while the MAX seemed no different than the 737NG.
A friend of mine has flown with a major carrier for over 30 years, avoiding McDonnell Douglas and Airbus (or as he says, Scarebus) like the plague.
Too many of his fellow pilots from his airline complain of the Airbuses having minds of their owns and ignoring what pilots input into the controls.
On the other hand, he likes piloting the MAX. He believes that the MAX has a smoother ride, flying more like the 767, which he flew for 15 years.
Let's remember that on Pan Am's inaugural 747 flight from New York to London, the plane went tech after leaving the gate. After a delay of several hours, Pan Am had to swap aircraft.
I was on an AA flight on a 772 from DFW to ORD. The plane had just come out of the maintenance hanger. The first delay was due to a software upgrade that hadn't been installed. Then, the hydraulic system failed. After two hours, we wound up swapping aircraft for a 772 that had just arrived from Europe.
Thank you for your input Chuck, I can concur that the MD crates did have a poor reputation this side of the pond.
I did laugh at your “Scarebus” quip. It reminded me about a tactical landing I undertook after qualifying on the A400M Atlas, according to the Load Master there must have been a few brown skiddies accompanying the troops off the ramp.
I enjoyed the adrenaline rush anyway.
As they say …. “Every landing you walk away from is a good landing” …. :-)
…. CORRECTION ….
Not Atlas …. C130!!
Indeed I have heard/read about the A320's / A330's ( spooky ) automation 'incidents'....
But I must be the only one seeing the irony in your comment about 'Airbuses having minds of their own.."
Has anyone heard of the 737MAX's M.C.A.S. ? That pesky little bugger that brought down two aircraft and killed hundreds of poor trusting souls.
Hopefully now that issue has been fixed once & for all time, but yet...
Indeed I have heard/read about the A320's / A330's ( spooky ) automation 'incidents'....
But I must be the only one seeing the irony in your comment about 'Airbuses having minds of their own.."
Has anyone heard of the 737MAX's M.C.A.S. ? That pesky little bugger that brought down two aircraft and killed hundreds of poor trusting souls.
Hopefully now that issue has been fixed once & for all time, but yet the MAX still haunts with it's 'jettisoning' exit door plugs, etc.
I guess I'd still trust those MAX pilots, though, as their lives are just at the same risk as their pax aboard those damned aircraft.
@AeroB13a
Good, you'll never get to fly ANA.
You don't deserve that treatment anyways.
Do give me one good reason for flying ANA Mason?
It's NOT a ' North American ' airline, and has a better ' service clutcha ! '
Does that count ? ... lol
** cultcha ! ** (damn auto-correct fights my illiterate spelling skills ! )
Bossa, I’m presuming that your post above is referring to my previous post?
Working on that assumption, I am only too well aware of the standards of the ANA airline. Currently it is rated at number four in the World Rankings.
For that reason alone I would quite like to give it a squirt. However, I would never be forgiven for flying with them and it could well end in divorce. Sadly, my...
Bossa, I’m presuming that your post above is referring to my previous post?
Working on that assumption, I am only too well aware of the standards of the ANA airline. Currently it is rated at number four in the World Rankings.
For that reason alone I would quite like to give it a squirt. However, I would never be forgiven for flying with them and it could well end in divorce. Sadly, my wife's father suffered at the hands of the Japanese military, during WWll. Enough said?
You really won't take chances or play the odds when " The World's Favourite Airline " pulls a last minute equipment swap ?
Even though your USA sojourns are diminishing, I do hope it isn't reflected in this site, as I enjoy your pithy retorts....
I can understand any apprehension clearing US CBP these days & apologize on this country's current so called administration....
Cheers mate !
~ A fan on the 'Left Coast' but 'right' side of the pond ?
Touché bossa, thank you for making me laugh on this UK dull evening.
It makes a pleasant break from being eaten alive by my six months old Cocker Spaniel …. she is an English Cocker …. no colonial offspring on this right side of the pond …. :-)
Glad to be 'in your service' !
Will you allow me the 'plaisir' of recommending a franchise tutor to the 'young one' after prioritizing the 'potty training' in preparation for that forthcoimng 'La Premier voyage' ? Or will that 'ruffle' her feathers regarding her 'English' heritage ? (my most humble apologies for somewhat mixing the metaphor ! )
:)
Ah, just sounds like 'hangar queen' royalty ...too bad... !
Could this be related to AA's new inflight ' lemonade inspired ' beverage ?
...lol..
After all, we're talking 'Boeing' here ...
Like the saying goes "if it's a boeing, I ain't going"
Imagine being proud of being a snowflake and saying it aloud.
“Snowflake” and “Eskimo” are racist terms on the right side of the pond, don’t you know Mason?.…. Something akin to the ‘N’ word used in some other countries.
Do take care old bean …. :-)
'right' in the geographic sense or 'correct' sense ? ..lol
Oh my, how do those Brit meteorologists evah cope with 'Winter precipitation' ?
...lol
…. :-)
bossa, please feel free to make up your own mind as to which sense …. :-)
I’ve been using that phrase for a few months now and you are the only one who has picked me up on it, thank you for the grin.
As for the “Brit meteorologists” …. if one observes the BBC Weather Service, it is forever Woke?
How about you post something positive instead of your usual miserable drivel.
Like others have said, head on back to NY you leech. You ruin travel for everyone.
@ Sen Blappig -- "Like others have said?" AKA you with a VPN? I last lived in New York nearly 30 years ago, when I was a little kid.
Sen Piggy, such a good name for a Boeing apologist who is only capable of posting the “Usual miserable drivel”.
As you are so clever …. I challenge you to find and post something positive to post about the unfortunate Boeing catalog of errors.
@aerpB23a - that one is the easy: airbus stock
Oh my ... Are we just having a 'bad day' , skipped your meds ( or need a refill ) ??
..lol
It must be horrific, having someone forcing you to read this blog !
LOL
Here comes Ben, followed by his army of the ignorant, ready to tear down ANYTHING positive in the airline world.
Things happen. Sometimes it's inconvenient. Other times it sucks. Stop with the incessant $#itting on your "hometown" airline (in quotes, newcomer).
If you hate AA so much, head on back to New York you miserable dork. You'll have more options there. People like you have ruined FL, and airline travel.
@ Ben Suxig -- I'll play along, as I think you're confused. I'm not in any way blaming American for this. I assume it's some sort of a defect with how the plane was delivered, and that American has no fault in this.
And regarding people like me ruining Florida? Lol that's a good one, I haven't heard that before...
Ben goes to bed too early to be ruining Florida.
Ben Sissy, as you are such a know-it-all, please allow me to challenge you to find “ANYTHING positive” to say about your AA experience.
Being one of the article authors “Army of the ignorant”, I for one would warmly welcome the benefit of your worldly knowledge. Go on Sissy, surprise us all with your wisdom if you possess any?
Woah dude, why are you calling Ben a sissy? Thats out of line...
Not reading my post is definitely “Out of line” …. Jorts.
Even the Apes character would not be so remiss.
Eewwww.... " Them's fightin' words !" ..
Can't we all git along ?
Now, take my hand as we sing 'Kumbaya' !
I think we can all take a little fun 'bitchy' humor ... it adds a little 'spice' to the pot !
LOL
The 787 are awful planes.
For a new design (sort ofl they are noisy (way noisier than any Airbus), overly packed with 9 across in economy (was supposed to be 8) and they often have nasty vibrations and rumbles (more than any other plans I have been on). I really don't like them. I think they are the first of the bad planes by Boeing. Then of course the Max... We shall see the 777x but I have low expectations..as we know the company has been going down the pan
[Citation needed].
For a showcase jet, this is embarrassing!!
Hope someone in the C-Suite stops obsessing over the strike point of his stock options and starts obsessing with airline business.
Now why on Gawd's green (but dryin') earth would a CEO pay any attention to anything other than the stock price & shareholders ?? .. lol
I still think about the Boeing worker who confessed staff in the assembly line left a ladder in the tail section and it remained there during a test flight. Of course new planes can easily have some issues but Boeing seems to have a heck of a lot of them.
Haven't heard of that specific 'oopsie'.... But are you sure it wasn't a very thoughtful & generous gesture to come in handy for future MX access ? ... lol
Sorry, I don't have a 'rationalization' for the liquor miniatures left aboard the refurb Presidential
747-8 !
That was my first thought, forgotten tools or screws/bolts in the skin of the plane bouncing around causing issues. But at the same time it may just be bad luck. I think of planes in a similar vein to ships sometimes, it is just superstition but sometimes the craft is just unlucky. Like North Korea's new destroyer lmao.