British Airways and partner American Airlines are to align their schedules to create a transatlantic shuttle service this summer.
Flights between Heathrow and New York will run hourly between 1pm and 8pm from March 27 and the airlines say there will also be a maximum of only an hour and a half between morning departures.
Currently, five of the 11 daily flights to New York leave London at almost exactly the same time, leaving gaps of up to three hours between services.
Four Chicago flights to London currently run at similar times at around 5pm and 8pm. Under the new schedule, the flights will be evenly spaced, departing at around 5pm, 6pm, 7pm and 8pm. The existing 9am and 9.45pm slots will remain as they are.
Two of the three Miami flights from London clash at around 10am, and these are being split to leave at 10am and 11am. A 1.30pm departure has moved to 1.35pm.
The joint business will also offer direct daily American Airlines flights between New York (JFK) and Budapest from April 5, and Chicago-Helsinki from May 1.
BA returns to the London-San Diego route from June 1 after a gap of eight years. Prices start at £566 return including taxes fees and charges.
The carrier also starts serving San Juan in Puerto Rico from March 28 with prices leading in at £530 return. Services from Gatwick to Cancun rise from two to three a week from March 27.
Meanwhile, Iberia is starting the only direct air link between Spain and California with a Madrid-Los Angeles service three times a week from March 28, with an additional flight between July and September.
The Spanish carrier is also starting flights between Barcelona and Miami three times a week from March 29.