audio-nut

The walk from T5 to the AirTrain is quite long and the walk from the AirTrain to T2 isn't exactly short. I would walk from T5 to T4, go through security and then take the bus to T2. I suspect the HA flight is usually on time or early so as long as you have a seat somewhat close to the front, I think you have a decent shot at making the connection.

ijgordon

Oh, well I think that decreases the likelihood that Delta will let you standby for the next flight. Not sure what DL's policy here is, I think AA gives some leeway for missed flights on BE tickets, but the terms of the ticket are no changes, no standby.

I thought about that, but I think it's also a pretty long walk from T5 (which is set back pretty far) to T4, if there's even pedestrian access (difficult to tell from Google maps satellite view, though I think there might be). Then you have to go all the way to the far end of T4 to get the jitney, at which point you're practically at T2 anyway! (Plus TSA will be much faster at T2).
If there's a way to know that the inner loop of the Airtrain is not operating normally, then I would definitely consider this, but otherwise I think it's extra hassle. JMHO.

Analise

You are going to need a lot of good luck given that your window is 70 minutes from when the inbound lands at T5 to your walking to the Airtrain, taking the All Terminals Airtrain, and then waiting on line at security at T2. The Airtrain is not your big worry as it's very easy; it's the security line at T2. If you miss your 8am flight and that is a roundtrip ticket, your entire ticket including the return flight itinerary will probably be cancelled and you might have to buy the walk-up fare.

I would not risk this. Whichever flight of your two separate flights has the cheaper change fee, change that itinerary to give yourself at least 3 hours at JFK just in case. The change fee will be a lot less money than a walk-up fare.

audio-nut

There is a path and I've walked it many times. You don't need to go to the far end of T4 to catch the Jitney, just past security on the west side of the building near gate 18 is the Jitney.

ijgordon

I consider that the “far end” of the main terminal building, when you’re coming from T5.

Brighton Line

Notification of Busstitution when some service is replaced by bussing is shown here https://www.paalerts.com/recent_airportalerts.aspx
You also can follow on Twitter, which I find better, @JFKairport

Exmaple:
AirTrain #JFK Advisory Due to construction, free shuttle buses have replaced AirTrain JFK to/from Federal Circle and all airport terminals: Now 10am, Sat, 3/16 Service will continue to operate normally between Federal Circle, Howard Beach & Jamaica Station.