A friend of mine was on JetBlue 669 on 07/16/17 from JFK to SJC. Two hours into the flight, the pilot announced that they didn't have enough fuel to make it to San Jose and so were returning to JFK. After another two hours of flying the plane arrived at JFK, and the passengers were put on a different plane that landed in SJC ~6 hours late.

It seems odd that running low on fuel would be handled by turning around and flying back to JFK when they could have refueled at ORD, IAD, or SLC before continuing on to SJC.

Another unusual thing is that the plane's altitude varied a lot. It climbed to 34,000 ft after takeoff, then descended to 32,000 ft, then 26,000 ft, and finally 20,000 ft. After the diversion it returned to 31,000 where it stayed until descending for landing at JFK.

The flight track log is here: <http://flightaware.com/live/flight/JBU669/history/20170716/2235Z/KJFK/KJFK/tracklog>.

I understand looking for more favorable winds by changing altitude, but 20,000 seems pretty low for an Airbus 321. In any case it doesn't appear that the jetstream at that latitude was very strong on that day (assuming I am correctly interpreting <http://virga.sfsu.edu/archive/jetstream/jetstream/big/1707/17071700_jetstream_anal.gif>). Note that the replacement aircraft climbed to 32,000 feet and stayed there until descending into SJC.

I've looked at AV Herald but they don't show anything for this flight.

Anyone have any insight into what happened?

marcos