I think that the first time you miss a loan payment, you'll receive a message saying the payment failed. But every subsequent time you miss a payment on that specific loan, you won't receive another message saying so.
In order to be shut down by the bank, you'll need to see the big red warning box on the front page of your airline, which only appears when you have both negative cash AND negative cashflow. And you'll need to have that big red warning box be there for 48 hours real time straight. The counter will reset if you're briefly profitable. If you last the 48 hours, it won't be a surprise shutdown, your airline will already be very, very dead.
Surprise foreclosures don't happen, so no need to worry about them. What can happen is a surprise death spiral, where some combination of staff payments, maintenance, tax deductions, plane deliveries, etc tips you briefly too far into negative cash, then you lose a couple of planes thanks to no cash for renewing leases, marketing stops and CI starts to drop, so you're now losing a bit more cash, can't pay to rearrange slots, can't get replacement planes, and just slip further into the red. At that point you can manually pull the plug, or wait the 48 hours to see what being foreclosed looks like. If you're too agressive and run your cash too close to 0, it's possible to kill a completely healthy airline that way.