The airlines will allow passengers to use and collect points interchangeably and offer flights on one another’s websites and apps.

Assuming that happens, JetBlue and United plan to link United’s MileagePlus and JetBlue’s TrueBlue Loyalty programs. The change allows members of each program to earn and redeem points on either carrier’s flights.

Blue Sky, the United and JetBlue partnership just announced, will give frequent fliers more ways to earn and use miles. Here's what you need to know.