To many people, once that door is closed, pilots sit back and do their own relaxing as they watch state-of-the-art technology fly us from place to place. "So, do you ever get to land or does it always just land itself?" many people ask in earnest. "With all those screens, do you ever get to fly the airplane?"
A simple answer to that question is, of course. On a typical flight, I'll hand fly (without autopilot) from take-off for the first 15-20 minutes of the flight and for approach and landing. Most pilots let the autopilot do the boring stuff like straight and level for 500 miles and prefer to do the fun and more challenging things like approach and landing. Not only does it keep our minds "in the game" but it also helps sharpen our flying skills so that, in the unlikely event we actually NEED them, flying remains second nature and allows us to concentrate on things like putting out fires or fixing malfunctions.
So, why use autopilot at all? The autopilot is integral to maintaining situational awareness. This sounds like a nonsensical buzzword you might hear in a lecture hall but, its application is absolutely critical. Instead of having one person fully concentrating on the menial task of flying the airplane, we hand that task over to a computer. Many times throughout the flight, we have far more important things to concentrate on than just pointing the airplane in the right direction. In the summer, that task is to focus on thunderstorms and fuel conservation.
That's easy, many people might say. Just, don't fly through them and fill 'er up. If I were the only airplane in the air, that might be a simple directive. Unfortunately, it's far more complicated and it starts well before you even get on the airplanes. So, let's start there:
Ground Stops/Ground Delays/ATC Flow Programs
For the frequent fliers, these terms haunt your dreams. When weather moves over your destination airport, and most likely, the airport where you have to make a connection, Air Traffic Control can meter the amount of traffic entering the airport's airspace. This is done to prevent airspace saturation and reduce workload on the human element of the system, the air traffic controller. When thunderstorms are present, many airplanes are asking to turn off their assigned course to avoid the weather and that creates chaos. Slowing the amount of airplanes en route or turning off the faucet completely, prevents unneeded delays and diversions.
Arrival/Departure Corridors
Around major cities like New York, Chicago, or Atlanta, the heavy demand on air traffic controllers is reduced by organizing the air traffic into corridors. These "corridors" are limited to a small number and are identified by their navigational waypoints formally or informally by their cardinal (N, S, E, W) direction. These waypoints are areas where low-altitude approach control will "hand-off" airplanes to high-altitude center control and vise versa
When weather is approaching a city, some corridors become blocked while others become supersaturated. In response, the FAA Traffic Management Unit or other independent Air Traffic Control Centers will put restrictions on the amount of airplanes entering their airspace. When that information gets passed to us, it'll come in different forms:
"Per TMU, your EDCT (wheels up) time is:"
"Center's request, all north departures are stopped."
"Due to weather, flights filed over BACEN have in trail spacing of (usually measured by miles or minutes)." --This means airplanes departing the same direction must have so many miles or minutes between them.
The same thing happens on arrival. Unfortunately, unlike on the ground, they can't just make you stop moving. Many of the tools they use include slowing the speed of the aircraft stream, rerouting the aircraft or, everyone's least favorite, holds (burning holes in the sky). To us, these sound like:
"Reduce speed to 280 knots for spacing into O'Hare."
"We have an amendment to your route due to heavy to extreme precipitation over WYNDE. Advise ready to copy."
...and the dreaded, "Speed your discretion. Expect holding over Brickyard."
Below I have attached a cool video showing a time lapse of ATC radar showing weather move through Atlanta. You'll see arrivals entering the airspace at 4 points around the airport (NE, NW, SE, SW). As the thunderstorms start to block the NW and SE arrivals, you'll notice them start to fly in circles then get rerouted to the other open arrivals of NE and SW. As the storms approach the airport and the rest of the holding aircraft land, there aren't any more flights arriving. Once that first group of planes started holding, TMU started sending out flow, delay, and ground stop programs across the country to slow the feed of airplanes into that Atlanta. Without those programs, airplanes would start getting stacked up over those entry fixes and eventually have to divert due to low fuel. These diversions cost companies a lot of money and wastes a lot of time whereas sitting on the ground at the departure airport costs only time, sometimes less than a diversion.
So, you still haven't answered your own question. What are you doing up there?
Good point. I had to first give you the why and now I'll give you the how. I've had many of these experiences dealing with weather and many of them come down to one common factor: do I have enough fuel?
When we first get our dispatch paperwork, amongst the 27 page behemoth of performance data, weather, and miscellaneous information, is fuel load and fuel burns. These fuel burns are very specific to altitudes since jet engines burn significantly more gas at lower altitudes than at higher altitudes.
For example, in my aircraft, the Embraer 145, fuel consumption at take-off is over 6000lbs per hour. That's a gallon of gas every 4 seconds. Can you hear the dinosaurs screaming? By comparison, fuel consumption at our maximum altitude, 37,000 feet, is 2400lbs per hour. That equates to 6 gallons a minute and if my terrible math is correct, 1.25 miles per gallon. Not quite what your Toyota Prius gets, but your Toyota Prius isn't carrying 55 people from Houston to Chicago in 2 hours.
The dispatchers break down our fuel burn into categories to help us. They give us en route fuel burn, reserve fuel burn (at least 45 minutes of extra fuel in the event of emergencies), alternate fuel burn (to a second airport if the weather is bad enough at the destination), and holding or contingency fuel. These fuel numbers added together constitute the legal minimum amount of fuel we have to have to push the throttles forward on the runway.
One more fuel number we get is load plan fuel. That's the total amount of gas we get from the fuel truck. Of course, it is always higher than the minimum amount of fuel because we have to use some to get to the runway. How much extra is a fine balancing act. In the airline world, weight is money. In the regional airline world, adding fuel might also bump passengers. So, while we could eliminate all this nonsense by just topping her off every flight, it would cost much more money. Heavier airplanes take longer to climb and burn more gas. Heavier airplanes also can't take as many passengers or cargo. So, on a balance sheet you would see less revenue and more costs.
The extra fuel that we get above minimum fuel we refer referred to as taxi fuel. Yes, we even have to know how much we use while taxing, and here's why.
When we push back from the gate, we usually run an auxiliary power unit (APU) to supply air to the air conditioning and to start the other engine, and of course, at least one engine. Airplanes don't taxi well without at least one engine running. Trust me. We've tried. Both of those run on jet fuel. During normal days, the taxi fuel is relatively inconsequential. We'll taxi out to the runway, wait a few minutes then take off. On bad weather days, things get more interesting.
The ability to taxi out on one engine is a huge benefit that few passengers understand. We use almost half as much gas and, during bad weather days, might allow us to take a full load of people versus booting two. Look at it this way, once we reach our maximum takeoff weight, if we had to run on two engines, we would have to remove one passenger and their bags for every 14 minutes of additional taxi fuel. With one engine, it's only one passenger every 24 minutes. What often comes into play in places like NYC since obstacles (Manhattan), short runways and high temperatures lowers how heavy we can be at takeoff. Plus, add in waits for departure over an hour long and you might have to start removing people.
Eventually you'll get off the ground and to your destination, at least that is the hope. Your pilots, however, still have to come back to New York. Most of us hope for days with really bad weather or painfully clear days. The decisions there are clear. You take on much more fuel or you just sit there on the ground until it's clear enough to go. What ends up getting us all flustered are the days with sneaky weather. Here's an example:
You're sitting back enjoying every single drop of your free can of Coke Zero. With as much as you paid for your ticket, you're going to milk every penny you can in free stuff. (I know you do it because, I did too). You hear the engines get really quiet all of a sudden and a few minutes later, the big wing off your left seems to point into the sky. Am we turning around? What's happening? What's wrong?
You have entered the hold.
"Well folks, from the flight deck we've got a little bad news for you. Looks like weather in New York has deteriorated faster than forecast and air traffic control has put us in a holding pattern over Cleveland. We are talking to company and ATC to try and get us an estimate of how long we'll be here and an estimate of when we'll be in LaGuardia. We'll let you know as soon as we have more information."
You think, those pilots are just up there staring out the window. Not so. Here is the same situation from our perspective:
"I don't know Joe. The SEC is always strong but Ohio State has more top tier QBs..." I say as I'm cut off by Indianapolis Center.
"Waterski 3356, contact Cleveland Center on 119.22. Good Day."
I read back the instruction. "1922 See you later, Wasterski 3356." As I dial in the radio frequency and prepare to check in with Cleveland, I finish my thoughts. "More top tier QBs than the whole conference. I mean, the 3rd string,3RD STRING, guy put a whooping on Alabama last year." I pause my rabble rousing. When I hit the button to switch the frequency, the radio waves are filled with talking from another flight.
"...expect further clearance at 2205 zulu. Is that a solid number for United 1176?" I sit in silence now and look at the Captain. Both of us look at each other seeming to say the same thing. I hope that hold isn't for NY traffic.
"United 1176. New York Approach just told me that all LaGuardia traffic is currently stopped. All they told me was to expect holding for awhile."
Frustrated, United replies back, "Awhile? How long is that? Twenty minutes? An hour? Tomorrow?"
"United 1176, I'm sorry. That's just what I've been told. I'll let you know if anything changes. Waterski 3356, was that you trying to check on?"
I jump on the radio. It wasn't us but I'll take advantage of the opportunity, "No sir, but we are with you 3-7-0."
"Roger, proceed direct Chardon, expect holding over Chardon. Advise ready to copy," the man in the air conditioned room outside of Cleveland tells us. As we copy our instructions and read them back to him, he continues on, "I don't know if you heard what I was saying to United, but all arrivals into LaGuarida are stopped. I just gave you a time because I had to. In reality, it's going to be awhile."
As he's telling us this, the Captain who is also flying the airplane this leg begins to pull the throttles way back in an attempt to conserve fuel. Also while listening to what he's saying, I program the flight computer for the holding pattern. When he finishes, I confirm that I'm aware the situation and am the first to speak. "Okay, I've programmed the hold, do you agree?"
"Looks good to me. I'm going to calculate bug-out fuel. Send a message to dispatch and tell them current fuel on board and that we are holding over Chardon (Cleveland). We have an alternate of Allentown but ask if Pittsburgh would be a better option for a diversion if we can't get beyond Cleveland. I've got the radios if you'd let everyone in the back know what's going on," the Captain barks out.
"Well folks, from the flight deck.." I say as I explain the situation. Once I've stopped, I send my message to dispatch.
HOLD.OVER.CXR.EFC.2205z.FOB.5000LBS.
ATC.SAYS.LGA.CLOSED.HOLD.UFN.
IS.PIT.BETTER.FOR.DIVERT.
Unfortunately, the only punctuation on our flight computer is periods, slashes, and plus/minus. Some days, I wish it was as easy as actual texting. It doesn't even come with a space bar. Once I'm finished, the Captain hands me the paperwork. "I've calculated our bug-out fuel. Do the same and we'll compare numbers."
What does that look like? I pull out my pen and grab the small magazine-sized release and begin digging through it looking for the information I need. It has a breakdown of each waypoint along the way and what the computer calculates as total fuel burn from take-off to each point so we can monitor for any anomalies. We should have burned 4300lbs when we got to Cleveland and 5100 at our destination. I think to myself as I'm scratching numbers on paper.
Okay, so it's 800 from here to landing. Plus...I look for the total fuel burn from NY to Allentown...uh, another, let's round up and call it 1100 to ABE. Then 1800lbs reserve. Hmm. Yeah, I'll throw on 200 for an extra approach. "Okay, I've got 3900, how about you?" The Captain agrees.
Even at the lowest possible fuel burn, we are still using around 2000 pounds of gas per hour. That only gives us 30 minutes before we have to start considering alternates and diversions. While we discuss our next move, we get word from the company:
YES PIT LOOKS BETTER FOR A
DIVERSION FROM CLE. SENDING YOU INFO NOW.
He has a space bar on his computer. It makes me jealous. As the printer spits out ten pages of information about Pittsburgh, we get word from ATC that our hold time has been pushed another 40 minutes into the future. No way we have fuel for that. I acknowledge and add on, "If that time holds, we're going to have to divert. For planning purposes, we're going to go to Pit."
As you can guess, they never let us continue. There was nothing anyone could do to make the fog go away in NY and we'd come as far as we could. It was time to divert. It's not a fun decision to have to make and an even less fun announcement to make. Of course, it's way better than the alternative which includes turning a 20-ton piece of metal into a glider.
Back on the ground in Pittsburgh, the process starts all over again. Ground stops, ground delays, wheels up times and fuel conservation. Once in the air, we held again for another 45 minutes but took on enough fuel to outlast the weather. At the end of the day, my 5 hour round trip from St Louis to New York turned into almost 9 hours. That's a lot of burned up dinosaurs. It's the least I could do after what they did to Samuel L Jackson on Isla Nublar.
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