Northwest had a decent amount of mainline flights and destinations including serving as Northwest's primary transatlantic gateway for years. Then by the late 80's and into the early 90's they code-shared with regional carriers Precision and Northeast Express which brought a whole flock of regional 19-seat routes into their network.
I'd be hard-pressed, though, to wager that Northwest was ever the largest carrier in Boston.
Doing a quick race-through of a 1991 OAG on departedflights.com here's what find flight (excludes Europe)
Delta -- 165/day total
58 mainline to 14 cities
80 large prop and 27 small prop to 17 more cities (and some overlap)
Northwest -- 130/day total
40 mainline to 11 cities
0 large prop and 90 small prop to 18 more cities
USAirways -- 120/day total
84 mainline to 18 cities
9 large prop and 27 small prop to 9 more cities
Doing a very dirty capacity guess where DL
get 140 seats per mainline and US gets 120, large props average 35 seats and small props 19, here's what I get for weekday capacity
Mainline + Codehsare Regional
These numbers don't include Northwest's international flying, which from a December 1992 NW
timetable shows 28 flights per week to 5 cities (AMS
). Those definitely bump up Northwest's numbers a few notches, but in capacity and frequency it still wouldn't be near the top.
I don't claim that this is necessarily the exact peak of the Boston operation although this is probably pretty close. The regional side may have grown a bit more but I don't think mainline ever got much past 40 for Northwest.
Certainly Northwest was a large player in these years, and they participated in some pretty big nonhub markets like LAX
in these years. But except for DCA
(where they inherited slots from EA
's demise) Northwest ran many of these destinations as 1x/day to coordinate with their handful of transatlantic flights. Northwest was a big player in Boston, but I doubt they surpassed DL
and US in most metrics.