MY son Chris is on a business trip in India this week, and his choice of how he got there from his home in Tucson underscores a reality in air service. More often these days, business travelers will choose to drive a few hours to a bigger airport because airline service is not as convenient at their local airport.

The reason, in my son’s case: Starting his trip at the Tucson airport would have meant leaving home at 9:30 a.m. for a connection on US Airways to Phoenix, to board a 9:15 p.m. nonstop to London on British Airways (connecting to Delhi). Instead, by driving the two hours from Tucson to the far bigger Phoenix Sky Harbor International Airport, he was able to leave home at 4:30 p.m.

That itinerary illustrates one aspect of what’s going on. Airlines have merged and cut routes and capacity while at the same time strengthening partnerships through giant global alliances and code shares — in which one partner airline actually flies the route, even though the ticket has been purchased on another partner airline. My son’s itinerary, for example, was booked as an American Airlines ticket, though his entire trip was flown on British Airways (but would have started out US Airways had he flown from Tucson).

British Airways and American both are in the Oneworld alliance, whose 13 members also include Cathay Pacific, Iberia, Qatar and Qantas. US Airways flights, as that airline completes its merger with American, will be within the Oneworld alliance starting Monday, when it departs Star Alliance, whose 28 members include United, Lufthansa, Singapore and Air China.