Turbulence: A Moment of Silence, Please.
Can we talk for a minute? I mean crew to crew? If you’re not flightcrew, this may be boring. Sorry.
But still, let’s talk about not talking for a minute. Here’s the deal:
We’re flying along fat dumb and happy. Then, it gets bumpy. I turn the seatbelt sign on. What do you NOT do? Or more accurately, what do I wish you wouldn’t do?
Call the cockpit. Seriously. What we get more often than not these days is, bumps, then ding-ding. “It’s for you,” I say to the First Officer, even though I am monitoring the flight interphone in my headset. Then I get the thanks a lot look from the F/O who reluctantly picks up the phone.
But I already know what the flight attendant’s going to say: “How long is it going to be bumpy?” or worse, “it’s really bumpy back here.”
First off, besides being an inane question, it shows a real lack of understanding of what just happened, plus what needs to happen. To begin with, if we knew the turbulence was there ahead of time, do you really think we’d fly into it? And given that we didn’t know it was there, how the heck are we supposed to know how long whatever it is we didn’t know about is going to last?
And truly, is it possible that it’s bumpy in back but not in the cockpit, so you really need to call and let us know?
Worse, either of us having to answer the phone with “we have no idea” or “yeah, it’s bumpy up here too” only prolongs the turbulence. Why? Because here’s what has to happen to get out of turbulence.
First, I have to decide if we can climb or descend. Are we light enough for a higher altitude and at that altitude, what is the margin between high speed and low speed stall? That is, a higher altitude may be habitable in smooth air, but not in turbulence–yes, the charts are broken out into smooth, light, moderate and heavy turbulence because it affects both speed control and the airfoil. Given that we are in turbulence at this geographic location, there’s a darn good chance it extends above and below us here as well.
If the margin between high and low speed buffet–Coffin Corner, as it is known–is sufficiently wide in my judgment, then climbing is one option.
The other is descent but that has a catch as well. Yes, the Coffin Corner spread is more favorable. But now we have to worry about fuel burn, which is higher in the denser air of lower altitude–which is why we cruise at the optimum altitude for fuel burn and Coffin Corner spread. I have to calculate whether the increased fuel burn allows for sufficient arrival fuel to accommodate the destination situation–and that varies.
Going into Omaha? Seldom if ever an arrival delay. Atlanta? Chicago, La Garbage? Better have flexibility and loiter time–which means fuel. Plus, the destination weather: with a low ceiling and visibility, even Omaha isn’t a slam dunk.
The final gotcha about descending to a lower cruise altitude because of turbulence is the increased fuel burn it’s going to take to return to the optimum cruise altitude when it’s reported smooth again.
With me so far? Then we need to call air traffic control and find out the ride report and the winds at a higher or lower altitude. Why? because a higher (or sometimes lower) altitude can have a significantly larger headwind, which again affects fuel burn, never mind arrival time. Anyway, calling takes time, then it takes more time for Air Traffic Control (ATC) to find the info we’re asking for.
Once we know the winds and the reported ride conditions, it’s back to a decision about up or down, based on the fuel endurance and destination weather factors I just explained. That all takes time too.
Once we’ve determined the best option, we request a new altitude from ATC, then wait for them to coordinate a new altitude–which also often comes with a catch: sometimes, they’ll need you to turn off course to gain spacing from another aircraft either in the airspace we need to climb through or at the altitude we’ve requested. Again, more fuel. Can we do that?
And then there’s the climb or descent itself: it takes minutes even after the minutes of calculations, requests and clearances.
None of that starts till we’re off the phone with you. Because in a two-man cockpit, both of us must be fully in the decision loop, as well as the execution of the changes in altitude and heading. And even then, we may find the new altitude is not smooth either–in which case the whole process starts over.
You can trust me on this: once we encounter turbulence, we immediately go to work to find a better ride. But none of this happens while you’re calling us. And we’d do it whether you called or not–so don’t delay the process.
If you’ve ever flown with me, you know this: if I know of any turbulence ahead, I’ll call back and tell you to “grab yourself a buttload of jumpseat–she’s gonna buck.” If I haven’t told you and it is suddenly bumpy–grab yourself a buttload of jumpseat–and wait for us to start the process of finding smooth air.
We’re definitely aware of the turbulence and looking for smoother air. All we need is a moment of silence.