Environmental Emissions

Exhaust emissions from commercial aviation have become a contentious issue in the recent past. To overcome a number of concerns arising from the public, and to address the true enviromental impact of aviation, a number of "CO2 calculators" have been proposed. Some are these are available from the airline operators, although almost none of them are reliable.

The true emissions depend on the aircraft, on the type of operations, on the passenger load, and most crucially on the distance flown. Major airlines carry bulk payload to maximise their commercial revenue. Although this is a different case that will be presented at a later time, we point out that whenever bulk is carried along with passengers, the measure of CO2/pax or CO2/pax/n-mile is not an accurate measure of the environmental emissions.

Following extensive studies using the FLIGHT application on a number of large commercial jets, we are in a position to offer unbiased and accurate technical advice on aviation emissions.

 

Emission Analysis of a Boeing B777-300

The FLIGHT software can be used for detailed emission analysis. The graphs below show the CO2 emissions per n-mile and per passenger for a Boeing B777-300 with GE turbofan engines.

 

Emission Analysis with 75% Passenger Load

This case refers to 75% passenger load in a 364-pax configuration, with 1,000 kg of bulk payload, standard day and -2 m (-3.9 kt) cruise headwinds. The result shows that there is more economy to be achieved by long-haul flights, whilst a short hop (anything below 500 n-miles) is comparatively uneconomical and not environmental. Note that for this aircraft, the CO2/pax/n-mile flattens out at around 3,000 n-miles. Beyond this distance, there is a slight increase in specific emissions, arising from the fact that a larger portion of the all-up weight (AUW) is made up of fuel.

 

Boeing B777-300 emission analysis with 75% passenger load

Boeing B777-300 emission analysis with 75% passenger load

 

Emission Analysis with 100% Passenger Load

The case shown in the graph below is almost the same, except that the aircraft is full (it carries 364 passengers). The main difference between the two cases is that a full aircraft has lower specific emissions.

 

Boeing B777-300 emission analysis with 100% passenger load

Boeing B777-300 emission analysis with 100% passenger load