Dal3834 diverted from LGA to JFK
 

Is it possible that the mechanical issue had to do with the airport rather than the plane? For example, a jet bridge was broken at LGA which would have stranded DL 3834 without another available gate to dock at? I imagine that there are certain times at LGA where there are no spare gates available at all.

I'm sure they have multiple gates that could handle an e175, but at a busy time of day, they may all be occupied back-to-back. At any rate, @jrkmsp's explanation seems more likely.

Regarding landing at the wrong airport, it's definitely an inconvenience, but to me it seems like a much more reasonable option than delaying the flight further and wasting fuel hopping from JFK to LGA.

Is it possible that the maintenance the aircraft required would be more easily serviced at JFK? Maybe an issue was discovered inflight and dispatch figured "might as well put the plane somewhere they can fix it".

Happened to me a few months ago. Flight was 2 hrs delayed for weather. Delta had to pay for a taxi from JFK to LGA so I could pick up my car.

It was land at JFK or not at all because "no available gates"

Runway friction - or lack of it - is a factor in landings. It's typical for Boeing's performance charts (as an example) to cite both dry and wet runways.

If there's any question about the stopping ability of the aircraft, it's always the captain's prerogative to find the longest runway available within reasonable proximity. When there's an aircraft mechanical issue that may affect safety, passenger connections become an afterthought. Why would a pilot decide to continue to LGA if JFK is a viable option, DL has a MX base there, and they have a runway over 14,000'?

Edit: Saying LGA "can handle a 767-400" isn't telling the whole story. Sure, a lightly loaded 764 could get in an out of LGA with no mechanical issues. However, a 767-400, at MTOW on a warm day, needs 11,000' for a balanced field takeoff. And you bet if that 767 took off, had a mechanical issue and had to return for an overweight landing, it wasn't going to come back to LGA.

If there was some issue with flaps, hydraulics, brakes, or even just an indication that there *may* be a problem with these, you look for the safest place to land. A 14500ft runway has far more room for potential braking problems to be worked out than a 7000ft one does. Passenger convenience takes a back seat to safely landing the airplane.

Worked in system control for many years. I can't ever recall an airplane diverting to another airport just because a gate wasn't immediately available. We don't have the whole story here, but LGA has other considerations (curfew, lack of ramp space to hold) so perhaps LGA tower wouldn't let them land? Of course, there's also the whole Gov't shutdown thing going on that LGA has been in the center of. Unknown how or if that could be an issue.

DL says it was a mechanical issue, so far, there doesn't seem to be any reason to refute that. Without any contrary evidence, I'll take DL's reason over the reason allegedly said by "they".