This is the industry that generated the famous story where American saved $40,000/year by going from two olives to one in their in-flight salad. United saved $300,000/year by printing their magazine on lighter paper. If you work at an airline and find a way to shave off a dime in fuel costs per flight, you’ll get articles written about you. And we’re supposed to believe that these companies don’t care about wasting fuel now that their schedules are padded out a bit?
To add to your list of examples. KLM, for instance, was one of the first to introduce a system that would allow certain flight data to be uploaded into the flight computer as opposed to be requiring the pilots to enter it by hand. Other than fewer errors, they touted potentially saving pilots a couple minutes of data entry as one of the chief gains of the system.
Article tl;dr -- Airlines used to get from airport to airport faster. Airlines used to be late a lot of the time. Airlines increased their estimated flight times in order to achieve higher on-time percentage. The reason they did this instead of just being faster is that they love using more fuel.
I'm not anywhere near the airline industry myself. The next time I see misreporting on my own company or industry I'll look back at this and remind myself it could be worse.
That's not the populist notion on corporations at all. The populist notion is that corporations' incentive structure, set by their board/leadership, causes them to act at the expense of rank and file workers and consumers.
That's very different than "evil" or "stupid".
They are models, specifically sanctioned by law, that are organized around particular sets of interests.
Just because there are subsets of people whose self-interest is aligned with particular corporations' doesn't mean that those interests are aligned with the self interest of everyone, or even a majority of people.
And this isn't to say that there isn't an important role for corporations to play in the world, but to suggest that their form and function is the result of everyone acting in their self interest is oversimplifying things dramatically.
"The secret to become millionaire is to be a billionaire and buy an airline"
It's counter-intuitive, but an aircraft can be more efficient at higher airspeeds. The reason for this is that, unlike a ground vehicle, an aircraft in level flight must expend energy generating lift to balance its weight. This loss of energy shows up as lift-induced drag [1]. As airspeed increases, the losses to lift-induced drag decrease, while the losses to aerodynamic drag increase. Where the point of minimum total drag lies depends on several factors including weight and altitude. See [2], which contains a chart for a generic aircraft which is 5% less efficient at Mach 0.72 than it is at Mach 0.80.
1. https://en.wikipedia.org/wiki/Lift-induced_drag
2. http://atmseminar.org/seminarContent/seminar11/papers/481-Je...
As another commenter pointed out, even if the gate isn't ready yet, there's always room to wait somewhere on the taxiway (this has happened to me a few times recently). They'd rather wait on the ground with the engines idling than circling around in the air with the engines running at speed. Plus, it's not like gate availability is affected by schedule padding anyway; there's only so many gates at an airport, and they always are trying to turn over planes as fast as possible.
It's like if someone said, "going a little slower on the highway [typically ~60 mph+] saves on fuel" and someone pedantically ButAkshully'd that cars are more efficient at 40 mph than 30 mph because of engine performance.
Edit: Ironically, I'm the one normally promoting my "Scylla-Charybdis heuristic", that you should be able to identify when tweaking a parameter goes too far. But here I think the context of the tweak was clear enough that this caveat was a distraction from the core point.
In practice they save fuel by flying slightly slower. But, their are many other considerations like weather that cause airlines to fly slightly outside of optimal altitudes and speeds.
I was flying to Edinburgh for Christmas a couple of years ago, we were slated to leave at 9pm and arrive at 9am (7 hour flight + 5 hour time difference, made sense).
Then the plane was late getting to us, and they didn't arrive until 9:30, they quickly kicked out the passengers, then the new crew climbed aboard to start cleaning. By 10pm, we were still waiting in the terminal. at 10:45, we were finally allowed to board the plane, and after a couple of minutes it backed away from the gate and taxied to the runway, where we sat for over an hour. We were the last scheduled departure, and when the plane arrived late, the de-icing crew had gone home. We didn't leave until after midnight.
And we arrived... at 8:45 am, 15 minutes earlier than scheduled.
I slept, so I'm not sure if we hit some massive jet stream, or a black hole, or what, but that was the day that I stopped believing flight times.
Edit: Took this photo[1] waiting outside the hotel for an early check-in.
1: https://megapickles.photo/2017/12/25/reflections-of-edinburg...
I suppose "flight time" should technically be defined as "time in the air", but realistically, "time it will take you to get from airport A to airport B" is a much more useful metric to passengers.
When your plane is extremely delayed, to the point that you're the last flight taking off from your airport (and thus likely a large set of local airports), this makes the likelihood that a huge amount of airspace is more clear around your flight path now than it was for the originally scheduled flight. The updated flight path might be massively more efficient, hit favorable wind conditions, open up different speed options along the way, etc.
Since flight times are dependent on a large amount of conditions that are pretty volatile with respect to time, the original estimate was probably true, but with changing conditions and flexible scheduling, they managed to get you where you were going on time.
So, sure, maybe the 'flight time' isn't true, but it's a pretty clear indication the arrival time is.
This is exactly how developers need to think about how they communicate schedules to management. Missing an agreed upon date is usually a much bigger deal than pushing the agreed upon date out from the get go.
Possibly lower emissions per minute, but if they are in the air for significantly longer, then that may be cancelled out by the extra time.
Often, although fuel efficiency drops off sharply as you go above a certain speed in a vehicle, going slower than that speed is not significantly more efficient per minute, and can therefore be less efficient per distance.
Driving a car for 100 miles at 30MPH is typically less efficient than doing so at 60MPH. Driving that distance at 90MPH is even less efficient.
Fuel expenditure falls in to two buckets:
1. Moving the vehicle. Accelerating to cruising speed and fighting the deceleration of friction and air resistance.
2. Keeping the vehicle running. Lights, climate control, that sort of thing.
My guess would be that the vast majority of fuel usage for planes is (1) not (2). As evidence of this, airlines care deeply about costs. It's not a high margin business (any more). My argument is that if it wasn't overall more fuel efficient to fly slower airlines just wouldn't do it. More evidence, the latest planes (A350, B787) have a lower cruising speed than, say, the 747. This also wouldn't be the case (IMHO) if it didn't decrease fuel costs.
Also, is it necessarily fuel costs behind the decision to steer away from 747, or could it be other costs, like plane utility and capacity, parts and service cost, and the requirements of cross training?
If an aircraft even has the capability to hover in place, it usually has to expend even more fuel to do so than flying an orbit or holding pattern. The ideal way for an aircraft to handle the counter-gravity force is to push an infinite amount of air downward at infinitesimal speed. A helicopter would want to have infinitely long rotor blades, rotating at an imperceptibly slow rate. Obviously, we can't do that, so very long blades spinning slowly enough to see them move is the best compromise we can manage. The output of a jet engine is a relatively small amount of air, moving very fast, but the jets push the craft though the atmosphere, and the wings translate that forward motion into pushing a larger amount of air downward just a little bit, for more efficient lift. Vectoring the engine thrust downward to hover in place means you lose that efficiency boost from the wings. Also, rotary-wing aircraft that are heavily-laden experience "coning", which reduces hover efficiency by making the force from each wing slightly off vertical, and some of the lifting energy goes into canceling out a lateral wobble.
Keeping a plane in the air for another 15 minutes of fighting gravity just isn't significant compared to the effects from changing its speed away from the aircraft's efficiency optimum in order to arrive 15 minutes later, or from fighting air resistance by doing a holding pattern at optimal speed and altitude for enough extra distance to expend another 15 minutes. As long as the flaps are not extended, the plane is just not very concerned with gravity.
Also, once you hit about 11 km/s, you don't need to expend any more energy on counteracting gravity, anyway. At that point, it's all about atmospheric drag.
An approximate description of a train.
For many vehicles, the difference in that factor between running at ideal cruising speed (the 60MPH car in both of our examples) and a lower speed is minimal, and could well be offset or overtaken by the extra spend in (2). This is my 30MPH car example.
Running at a higher than ideal speed is inefficient in this factor and increases fuel usage a lot. This is your 120MPH (my 90MPH) example.
As you say, airlines care deeply about costs. It is highly unlikely that they were mostly running their planes inefficiently above design cruise speed, and are now slowing down to at or below the design cruise speed. It is more likely that they have always been at around the optimal speed, and are now going slower than that to reduce the risk of fines.
Note that the bottom half of the article is a sales pitch for his business flow product!
Quite often airliners arriving at my local airport ask ATC for a dogleg course for 'additional track miles' on approach to pad their arrival time or burn-off fuel.
It's purely a request by the pilots, not a traffic issue. CO2 being traded directly for convenience.
There are also maximum landing weights (which are different from max takeoff weights) which could potentially be a factor.
It used to be any two flights even remotely close to landing and departing time and I was really hesitant to book them .... less so now.
>Just the other day I flew out of NYC and it took us 40+ minutes of being in a queue to take off behind 15-20 other planes because reasons.
That anecdote is exactly why the claim that there is no incentive for airlines to increase efficiency is so bogus. The vast majority of scheduling delays occur because of on-the-ground and ATC issues that are the sole responsibility of the airports involved. An airline can't do much to combat the inefficiencies that result from a notoriously incompetent airport and their inability to properly manage traffic so gates clear on time.
Guess what the engines are doing at this time. Even worse if they tell planes to circle before landing because there are too many landings at this time.
Usually one engine is turned off...
For example, the latest thing American Airlines seems to be doing is changing schedules in radical ways between time of purchase and day of travel. The last three itineraries I've had on American, I've gotten an e-mail weeks after buying the ticket saying that one of my flights now had a schedule several hours after the originally booked and ticketed flight. What then, predictability?
If this is recent however it's not entirely their fault. AA is a big customer for the 737 MAX. That plane's grounding has hit their schedule pretty hard. Most of those flights involved Miami for some reason but to backfill those routes they've taken planes off existing routes that weren't fully utilized. Like I'm fairly sure some weekend JFK-SEA flights were canceled and my guess was to free up an old 737 for some other route.
They're also the largest airline in the world I believe so i can't even begin to imagine the complexity of the logistics of this like making sure you have a flight crew in the right place as well as all the other changes to services like maintaining the plane, cleaning it after a flight, baggage handling, stocking the plane with food and drinks and so on.
If your changes in itinerary were less recent than that then my next question is does this involve regional flights? I fly between hubs mostly so I haven't had that experience.
Effectively they are operating a fleet that is 2.5% smaller than normal. I expect some impact to their schedule, but it shouldn't hit it that hard.
It is not only about fuel. Right? Article is talking about punctuality. People will use competitors if an airline is not on-time. So with padding they create a safety gap to make sure they arrive on-time.
I believe 15mins safety gap is fair as it is extremely difficult and expensive to always operate on-time without a major airport redesign and technological advancement in how the system works. It gives passengers a reliable arrival time to plan whatever they have next.
The leading "What airlines don't want you to know" tone of this post is probably to manipulate the reader into reading the whole article, so you can find out what "they don't want you to know", which never really comes.
Here the airlines are doing pretty much exactly what I, as a passenger, want, which is to predictably arrive at an airport by a certain time more often. If a plane takes less time to fly somewhere some of the time because of weather, timely takeoff from departure airport, landing slot availability at the arrival airport or whatever, I don't really care. If they arrive late however, that can be a huge problem, particularly for making connections.
As for CO2, the plane flying slower is more fuel-efficient. Isn't this lower CO2 emissions?
40 years ago there were so many fewer planes in the skies. You could fly as fast as you want, take off when you want (pretty much) and land when you want. Well, lack of satellite navigation and tracking mattered but basically the skies were less crowded. Just the other day I flew out of NYC and it took us 40+ minutes of being in a queue to take off behind 15-20 other planes because reasons. You have to have that padding in your schedule.