Here I sit in wonderful Asheville, NC (well, I assuming it’s wonderful, but we stay right next to the airport across from the interstate) wondering how tonight and tomorrow is going to play out. We are scheduled to depart here at 6pm tonight and head down to Charlotte. Then we are supposed to fly up to Albany, NY for the night. Tomorrow morning at 9am we deadhead down to Philly (on Air Wisconsin) and then fly PHL-New York-Dayton-New York-Dayton. At least that’s what we are supposed to do.
The weather here in Asheville is sort of dreary, but ok. It is supposed to start raining/drizzling later this afternoon. Charlotte is supposed to be about the same, so no problems getting down there. Then the fun starts. There is a major weather system (the second in 4 days) working its way west to east across the country. Right now it’s running in a north-south line from about Chicago on down to Little Rock. The southern half of the country is getting rain (hence the current Asheville weather) and the northern half is getting snow. Airplanes fly just fine in rain, and as long as it isn’t heavy, they do ok in snow. The problem lies in the fact that the rain doesn’t just magically, instantly turn into snow. There is often a line (both on the weather map, normally some color of pink or purple and vertically through the air as the temps change at altitude) where the precipitation isn’t snow and it isn’t rain.
There are all sorts of things that can be falling out of the sky in this zone. Freezing rain, hail, ice pellets and freezing fog are all possibilities. The problem is we can’t operate for very long in most of these forms of precipitation and we can’t operate at all in a few of them.
A quick note… we can land in pretty much anything. We do have to worry about airframe icing (ice builds up on the airframe and both adds weight to the airframe (bad) and changes the aerodynamics of the airframe (very bad). But we have a heated wing, engine inlets and as long as we have some airspeed the design of the plane prevents ice buildup so unless it is VERY bad (heavy or severe icing) we mostly can hold our own). However, once on the ground sitting at the gate, most of those protections go away. Hence, the only way to get the ice off the plane (and keep it off) is to spray deice and anti ice fluid. The deice pretty much uses the heat of the liquid and the force of the spray to melt/knock ice off the airframe. Then the anti ice fluid (which is much heavier and “sticks” to the plane) prevents new ice from forming. At take off speeds it is designed to slide off the plane as the normal anti ice systems kick into effect. The problem is depending on the air temperature and what is falling out of the sky, that anti ice fluid will only provide protection for as little as 10 minutes, or in some scenarios (snow falling mixed with ice pellets) no protection at all. Hence, we are grounded.
So, looking at all those factors, and then looking at the weather forecast for tonight and tomorrow, I see Dayton is supposed to be bad all day today, but improve (somewhat) later this evening. Unfortunately we aren’t going to Dayton tonight. Albany is supposed to be good (well sort of good) at our time of arrival tonight, but get bad shortly there after, including heavy snow at our time of departure tomorrow morning. Philly is supposed to go bad late this evening and stay bad until the forecast expires for tomorrow afternoon. New York is going to be ok, until about the time we are supposed to be heading up there from Philly at noon tomorrow.
The danger is, we get into Albany tonight, and then the originating crew who is supposed to take the plane we are brining in back out first thing in the morning gets stuck because of the weather. Then we get stuck because AWAC can get out of Philly to come up to Albany. So now we have a plane and two crews stuck in Albany (not to mention all the passengers, but when the weather goes bad, an airline mostly has to worry about positioning crews in such a way that when the weather gets better they can start the recovery process quickly). Best case scenario with that, the early crew is able to to get out and we somehow are able to get down to Philly, we’ve still got a day in the north east corridor in front of us with bad weather. And stuff backs up there even when the weather is good so it will be beyond ugly.
Operations has a whole bunch of options. They could just wash out our entire day of flying tomorrow and preemptively cancel our entire day. That means either we would go from Charlotte right back to Dayton tonight or we would try to get into Albany tonight and then instead of leaving the plane there we would fly it back out either to Charlotte or to Dayton right away. We could go to Albany and then try to get to Philly tomorrow and then either deadhead right back to Dayton or try to do one New York trip and drop the last one or they could just send us on our full day and just deal with what ever happens. Right now there is no way to know. Mostly they just play these things by ear.