Diverted flight and compensation
 

I was on UA 4435 EWR-YYZ on Jun 20. Scheduled departure at 1520. Actual dep was 16:58. All was normal as indicated shortly after take off until 30 minutes prior to arrival. We were advised that due to adverse weather condition (rain and thunderstorm) suspended all takeoffs and landings.
As our aircraft did not have enough fuel to circle around YYZ and the crew on board would not be able to work further hours as per regulation, we would be landing in BUF. After landing in BUF, we waited 1.5 hours for a bus to take us to YYZ. Actual arrival at YYZ was 23:05.

I understand that the airlines have responsibility to your final destination regardless of the mode of transport. However, why did UA choose to land in BUF and not YHM, Hamilton Ontario. There was no adverse weather affecting YHM. Are there any regulations as to which alternate airports an
airline can divert its flight. Furthermore, would passengers be entitled to any compensation based on the arrival time in the final destination due to the diverted flight?

Airlines generally land where they have operations and not at the absolute closest airport to the intended destination.

There's no compensation due in situations like this when flights are diverted due to weather.

None that I am aware of but airlines have preference for where they have staff to assist and/or are sure the right type of equipment for that aircraft type is available.

In true emergencies, the above considerations will have little weight and the "closest" airport capable of handling the aircraft and passengers will be selected. In non-emergencies, the convenience for the carrier will carry more weight.

Weather caused diversions are outside the control of the carrier, so no.

There are no mandatory compensation laws in the US for delayed flights (even if it is their fault). The only mandatory compensation situations are for involuntary denied boardings due to oversales. They might give you some miles or a voucher for future travel if you complain, but the amount is at their discretion.

Question: if crew times out while in the air, that isnt cause for diversion, correct?

So crew timing shouldnt be 'the reason'.

But even without that as an excuse, the ariirline acted within the rules. IMO

The divert was likely due to fuel. The fact they then couldn't continue on to YYZ after landing in BUF (presuming the weather cleared enough to do so) would likely have been due to crew hours.