The busy pre-Christmas weekend saw a ton of cancellations with Delta choosing to be the most proactive on that front. In fact, according to FlightStats.com, Delta ran a mostly smooth operation until noon on Saturday. At that point, it seems they made the executive decision to pre-cancel most of the rest of their flights that day before the weather arrived. Only a handful of long haul and international flights left the rest of the day. On Sunday, Delta continued with its aggressive pre-cancel policy. All flights were canceled through noon and only a couple flights got out before 5p. Between 5p and 9p, they seem to have operated about half their flight schedule. After 9p, it looked like relatively smooth sailing and all was back on track.
American and JetBlue used a different strategy. While they did pre-cancel, they waited until later to do it.
American didn't really start canceling on Saturday until the mid-afternoon bank of flights. It really kicked in around 6p after which very few flights got out. On Sunday, only a couple flights got out before noon and those were Caribbean-bound. The first domestic flights didn't really get started until noon. The afternoon delays weren't too bad, but they didn't really start getting planes out on time until 7p.
JetBlue is where most eyes were probably watching because they're the ones that melted down on that fateful Valentine's Day a couple years back. Back then, they tried to run their full schedule, no matter how late flights went. That didn't work well. Not only did they fail to do it, but they had so many airplanes and crews out of place that they didn't recover for days. It appears that they've learned their lesson.
JetBlue started canceling some flights in the early afternoon on Saturday, but they actually did get a fair number of flights out until 7p, better than other airlines. At 7p, that was it - no more flights. They also started up earlier than others on Sunday. Their first flight got out at 616a (a flight to Ft Lauderdale that arrived 2 hours late). Still, there were a ton of early morning cancels, but it looks like by 9a most flights were going. The tradeoff here is that they took more substantial delays than the other airlines, but they probably got a higher percentage of their customers out than the other airlines, even if they were delayed. By 3p on Sunday, the delays were decreasing and flights started going on time. By Sunday evening, things had calmed down considerably.
So, from an operational perspective, these airlines all appear to have done fairly well. Only one problem - now there are a ton of holiday travelers who are stranded for days. But it could have been a lot worse.