Ly 3 & 21 tlv-jfk ?
 

I've noticed LY has been operating somewhat-unusual flights to JFK recently.

On 14 March (Wed.), 19 March (Mon.), and 21 March (Wed.), a 777 operated:
LY 3 TLV 2345 0620+ JFK

The return flights were the following day:
LY 14 JFK 1135 0410+ TLV
LY 14 JFK 1500 0735+ TLV
LY 14 JFK 1130 0505+ TLV

Anyone know why they operated such an unusual schedule, as opposed to adding daytime flights?

This week, LY has started operating LY 21/22 using 789 (starting Sun. 25 March):
LY 21 TLV 1350 1835 JFK
LY 22 JFK 2100 1425+ TLV

If these times look familiar, it's because LY loaded this schedule, effective 25 March:
LY 25 TLV 1350 1835 EWR
LY 26 EWR 2100 1425+ TLV

Since EWR isn't slot controlled, does anyone have a theory why the airport was changed?

As far as I can tell, the current NYC schedule is:
Overnight / Early AM: LY 1 JFK - 744 & LY 27 EWR - 789
Morning: LY 7 JFK - 772
Early afternoon: LY 21 JFK - 789
Late afternoon/evening: LY 11 JFK - 772

I’m booked on LY25 in June and it’s still there. You really frightened me, I checked my reservation immediately upon reading your message...

The entire month of June has LY25 scheduled and no LY21...

This time of year with Passover and Easter falling out this weekend theres more demand to TLV, and 1000s of kids learning in Israel for the year come back to be with their families for Passover

Cant speak to why they used the timings they did some might be in order to get the flight back to TLV or due to the plane being used on other routes and this is when they were available w/o causing hardship to its reg flights

1) As Craz stated above, it has somewhat to do with Passover.
2) As the 789's come online, LY plans to have 2 daily rotations into/out-of EWR and also an added rotation to JFK, making up for the loss in capacity from the demise of the 744. That's part of what you are seeing. More flights, smaller planes.