28

I'm going to simplify and assume that jets and cars burn the same fuel, and output the same exhaust, CO2, NOx and all. I'm going to compare only short-haul flights against cars. According to Wikipedia, an A-320-NEO does 1.95L/100km per seat. Assuming flying at 80% capacity, that gives us 2.4L/100km per seat. According to The Car Guide, a 2019 Honda Civic ...


27

The only reason for your flight to operate at such low altitude is because it is cheaper for them to do so. As you said it is due to weather, other route/altitude may not be available. They can cancel the flight but that is likely to be costly. They may have to find accomodation for you and crew until they can put you to the next flight. Sub-optimal flight ...


26

I used the playback function of Flightradar24 for the 18th at 23:00 UTC, and the amount of traffic above 10,000' (filtering by altitude) seemed very normal compared to other days. I'm baffled as to why they flew so low, but I can address your fuel question in some detail. The difference in fuel consumption is ~693 kg of fuel, and would cost an extra ~$415, ...


24

Here are some options for flying in an environmentally friendly way: Use an electric trainer: Since last year the all electric trainer aircraft Pipistrel Alpha Electro has FAA certification. Assuming the batteries are charged with renewable energy, this would mean no greenhouse gas emissions at all (excluding manufacturing). It will probably still take some ...


16

It was because they could get there faster on a "TEC route." IFR flights are subject to congestion management at the ARTCC level, which means they have to wait their turn in line to be allowed into the airspace. That used to be done with holds (and still is in many other countries), but the US will slow down aircraft, reroute them or even delay takeoff to ...


15

By using as much simulator time as possible.


13

It depends on what you mean by "environmentally friendly." Just for an example, let's consider a 1000 mile trip. An A320 burns about 5 gallons of fuel per seat per hour, and with 150 seats this comes to 750 gallons per hour. A 1000 mile flight will take about 2.5 hours, so this comes to 12.5 gallons per seat, or 1875 gallons total. This means that 2 seats ...


9

The 7:1 rocket figure is perhaps for the unrealized single-stage-to-orbit, getting a payload to low Earth orbit (LEO) is closer to 9:1, and going to the moon and back is 23:1 (Saturn V). If a soda can's content is the fuel, then the rocket stages that are jettisoned have better fuel to empty mass ratio compared to that soda can, so staging is not the main ...


9

While not specific to an A320, nor a make/model of automobile, these averages may help put your question into perspective. How any of it relates to "environmentally friendly" is purely subjective. "...the average fuel consumption in 2017 was 34 pax-km per L (2.94 L/100 km [80 mpg‑US] per passenger)..." from https://en.wikipedia.org/wiki/...


9

I am basing the following calculations on the excellent answer by Peter Kämpf to this question: How much of an improvement would a 1% weight decrease on an airplane be to the industry?. We can approximate the fuel usage with the Breguet equation $$ m_\mathrm{TO} = m_\mathrm{Landing} \cdot \exp \left( \frac{R \cdot g \cdot b_f}{v \cdot L/D} \right) , $$ ...


8

Learnt to fly a solar powered hot air balloon The UK's International Balloon Fiesta in Bristol is a celebration of all things hot air ballooning, but this year it's taken a big stride into the future. August 6th saw the maiden public flight of the world's first hybrid hot air balloon, which flies by heating regular air from the sun alone.Source In theory,...


8

The following table shows the long range cruise control data for a Boeing 737-800 (source: FCOMv1 Performance Inflight - All Engine PI.31.2): Let us consider a typical cruise at FL370 with a weight of $ 65 \, \mathrm{t} $. The table tells us that the fuel flow per engine would be: $$ \mathrm{FF} = 1231 \, \mathrm{kg}/\mathrm{h} $$ We are interested in the ...


7

This scenario isn't common but it isn't exactly rare, either. You take off with a full plane & lots of fuel for holding & an alternate, planning to arrive just at max landing weight. Then, due to shortcuts and/or better than forecast tailwinds, you under-burn & see that you'll arrive above max landing weight. First, the hypothesized rule in Part ...


6

Much like how a gas pedal controls the fuel input of a car's engine, so do the thrust levers on jet-liners. The coasting equivalent is idle thrust. The engine keeps running, but with minimal fuel flow. The minimum fuel flow is not fixed as it is a function of altitude, airspeed, and temperature. Nowadays it is typically managed by the FADEC, so the pilot (...


6

There is an existing triple redundant hydraulic system in those planes required used for the control surfaces. Those are not something you want controlled by pneumatics. This means the weight of the compressor, buffer tank etc. is already there and using it for brakes means you only need to pull a line from a supply/return line (which would also be near the ...


6

The flight crew is responsible for ensuring there is enough fuel on board before taking off. Further, they are required to check the fuel consumption en route at regular intervals to ensure there is enough fuel to continue. If fuel is consumed at a higher rate than expected, perhaps due to headwinds, the crew will divert to another airfield before the fuel ...


6

Overall, the two very different methods of transportation have surprisingly similar amounts of emissions. The exact circumstances make each better in some scenarios, but overall airplanes are slightly better for the environment for a 2-person trip. Expert Sources The general question here about cars vs planes has been studied in great depth by experts, so ...


6

The answers by Bianfable are pretty good. I'd add one more option: Use a powered glider. There are gliders with a small engine, electric or otherwise. Some look like propeller planes with glider wings, some have a much smaller engine and a retractable or foldable propeller. My favourite example is this one. These can take off under their own power, which is ...


5

TU-144 = 9.78 passenger mpg TU-144 figures found on another forum, from an official flight planning document: https://www.airliners.net/forum/viewtopic.php?t=1355819#p19483811 -- By comparison the TU-104A = 15.88 passenger mpg From an old Aviation Week story on the TU-104: http://aviationweek.com/blog/tupolev-104-harsh-proof-rapid-soviet-progress-1956 ...


5

That depends how you define longer in aviation. As you can look at it geographically or on the clock. The hard answer is no, the most fuel efficient route is the one that has the aircraft in the air for the shortest amount of time. If you can take advantage of a big tail wind 20 miles south of the geographically shortest route or at a slightly higher ...


5

The answer is pretty simple. A foot-launched glider (paraglider, hang-glider or ultralight) launched from a hill has zero emissions from the flight itself. It doesn't get more environmentally friendly than that!


5

For an A320, at FL 100 and weight 50 tonnes and ISA, the FF is 1028 kg/h per engine, so two engines is 2056 kg/h. Now for the same but OEI: the FF is 1891 kg/h (just the one engine). Scenario 1 is higher fuel flow rate. I'll explain why based on scenario 2. In scenario 2, with one engine inoperative (OEI), the remaining engine will run at higher power ...


5

The most obvious difference is due to the temperature of the air. Both turbine and piston engines are heat engines. They work by converting thermal power into mechanical power. The theoretical absolute maximum efficiency you can achieve is called the Carnot efficiency, $$\eta = 1-\dfrac{T_C}{T_H}$$ This is the efficiency of an ideal engine using the Carnot ...


4

On a flat plane, the shortest distance between any two points is a straight line, right? So if you were at A and wanted to get to B in as few steps as possible, you would walk a straight line. But what if there's a moving sidewalk along that route, going the wrong way? Now is the path of fewest steps still a straight line? Probably not: by adding a few ...


4

Yes there is a simple rule of thumb for what is known as Specific Fuel Consumption that you can apply to estimate the fuel burn of most piston engines: An air cooled carbureted engine, leaned, will burn roughly 0.44 to 0.45 lb/hp/hr. With Fuel Injection, a bit less, maybe 0.41 or 0.42-ish. Cars with electronic sequential fuel injection are in the high 0.3s....


4

It's not fixed, some of the variables are: Which 737 family and variant Flight (air) distance, which is affected by wind Passenger load. In general, for any current jet-liner's fuel mileage, I recommend Wikipedia's article on aircraft fuel economy. The figures are well-sourced, and structured nicely. Just remember to divide the mpg values there with the ...


3

Generally, the least time in the air the better, but it's mostly a maximum miles per gallon over the earth thing and this depends on winds. In the time/fuel burn equation, there is always a "sweet spot", a speed/power configuration that gives the most miles per gallon for "air distance" traveled, but how this translates to a maximum distance covered for a ...


3

Your definitions are correct and your derivations correctly use the law of conservation of energy, so yes, the power distribution change does happen. The more important question is what does this actually mean. Energy is a rather curious quantity in that while it is conserved in each reference frame (including non-inertial as long as appropriate potential ...


3

Interestingly there is one example of this entering service and provides a decent reference point. The Fokker/Fairchild F-27 had an all pneumatic undercarriage (breaks, retract, and steering). When compared with similar aircraft (role/size/era) like the Hawker Siddeley HS 748 or the Handley Page Dart Herald the F-27 actually preformed a bit worse although ...


3

Reducing thrust is the normal way to descend, though given that the prop is bolted to the crankshaft, you don't really have a neutral*. It's exactly the same as taking your foot off the gas pedal in a car. Depending on conditions, you may or may not want to go all the way to idle until you're actually on the runway, thought. You can use other techniques ...


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