The measure generally accepted in the industry for size-ranking is revenue passenger miles. When AA acquired TWA, the combined RPMs were larger than UA, which moved AA back into the #1 position. Incidentally, AA also has more employees and a larger fleet, but that isn't really relevant.

Also, I find it interesting that you complain about AA's "moderate European coverage" compared to UA's "LHR rights and mediocre coverage to the rest of europe," considering that AA not only has LHR rights, but also a larger LHR operation than UA (15 long-haul AA flights/day, only 12 longhaul + 1 short-haul flights/day on UA.) American also operates 4 flights/day to LGW to boot, making their total London operation a good bit larger than United's.

Same with AA's "moderate connections to Boston and New York"... UA flies 30 flights/day from BOS with no Express feed; AA operates 51, plus 76 more flights on Eagle. UA's flights serve 5 cities, all UA hubs; AA's flights at BOS serve 28 cities, mostly non-hubs.

NY market (all 3 airports): UA operates 57 flights/day to 8 cities, again, almost all hubs (exceptions are LHR, NRT, and SEA). This includes Express service. AA, meanwhile, offers 272 flights per day (again, including Eagle, which operates 90 of the 272 flights), serving 56 airports, again, mostly non-hubs.

So basically the only two points you raised that actually give the guise of AA being smaller than UA are the Asian and US West Coast networks.

(Note: some of these numbers may be off by one or two either way... they are hand counted from the electronic timetables of the respective airlines and represent flights scheduled on Wed, Jan 15, 2003.)