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Boeing 737 MAX - does this aircraft have an uncertain future?

Written by Dean Boljunčić.

Photo: © Boeing
Boeing 737 MAX

 

We are all familiar with the story of the problem of Boeing 737 MAX, its systems and unfortunately its crashes. After the approval of the FAA (Federal Aviation Authority) and recently the EASA (European Aviation Safety Agency), we can soon expect the return of the Boeing 737 MAX on the European sky. This is certainly a good sign for most of the aviation world, because it also means a return to the normalization of air traffic.

However, the question arises as to what fate awaits the Boeing 737 MAX (all its versions), especially in Europe?

Is it "business as usual" or is there still (for now) a hidden uncertainty for the Boeing 737 MAX?

Personally, I think there is, and I will try to explain which currently unknown fact may seroiusly harm the Boeing 737 MAX in the future.

For the purposes of this text, let's assume that passengers will not be afraid and refuse to travel with Boeing 737 MAX, and that it will gradually, with the usual dynamics, replace his older brother, Boeing 737 NG.

Over the past few years, Europe has strongly supported reduction of poluting gases, as can also be seen in the recently adopted Green Deal.

Initially, the care for the environment was realized through the aircraft noise level, which resulted in the standards described in ICAO Annex 16 (jet engines):

  • Chapter 2 standard - until 06-10-1977
  • Chapter 4 standard - from 06-10-1977 to 01-01-2006
  • Chapter 4 standard - from 01-01-2006 to 01-01-2017
  • Chapter 14 standard - from 01-01-2017

In the not-so-distant past, the aircraft CO2 emissions have also been discussed, and recently more and more attention has been paid to local air quality, ie aircraft NOx emissions. 

In addition to the existing proposals to limit the level of CO2 to gradual CO2 neutrality in air transport (for example, the Netherlands wants to be completely neutral by 2050), airports have formed price lists (Airport charges which do not include handling prices) that already have various ways to reward aircraft that produce less noise and harmful gases, but also to punish aircraft that produce more noise and harmful gases. Some airports have even completely prevented landings of aircraft that produce too much noise (up to the level of the Chapter 4 standard), although this noise level is acceptable in Europe (Chapter 3 standard)

To put things right in the perspective, the data were taken from publicly available ICAO databases on aircraft emissions and noise levels, available on the EASA website.

The analyzes explained in this text were conducted for the purpose of developing future airport charges, where the prices of aircraft takeoffs and landings would depend on the noise level and emissions of individual aircraft. Ecological performances were observed through noise levels, CO2 emissions, and NOx emissions.

That is why two flagships of the ICAO C aircraft, Boeing 737 MAX 8, and Airbus A320 NEO were used for direct comparison.

At first glance, both aircraft are very similar in their capacity and size, but when you go deeper into the technical characteristics of the aircraft, the differences are very visible.

It is important to know that the Boeing 737 MAX 8 comes equipped with a LEAP engine (often LEAP 1B27 or 1B28), while the Airbus A320 NEO has two engine options, LEAP 1A26 or Pratt & Whitney (often PW1127G-JM)

 

Aircraft noise level

When we look only at the noise levels of an average older Boeing 737 NG (737-800 with CFM56-7B26 engines), it has a higher noise level of about 7 cummulative margin EPNdB than the equally older competitor Airbus A320 CEO (Airbus A320-232 with V2527-A5 engines).

When we compare Boeing 737 MAX 8 and the Airbus A320NEO, again, the Boeing has a higher noise level by about 5 EPNdB cumulative margin.

These figures show and confirm that the Boeing 737 MAX has much lower noise emissions than the older version Boeing 737 NG, which is also the case with new version of the Airbus A320 NEO (New Engine Option) compared to the older version of Airbus A320 CEO (Current Engine Option). It is also clear that the new generation of Boeing, has a higher noise level than the new generation of Airbus.

When we go a step further and observe CO2 emissions, our reference database is the ICAO database (Emission database), which is based on the following measurement points and flight phases:

  • Take Off (T / O)
  • Climb out (C / O)
  • Approach (App)
  • LTO - Landing and Take-off cycle

LTO is taken as a reference point on the amount of gases emitted in one cycle (take-off, climb, approach and taxi).

 

CO2 emissions

CO2 emissions data are not included in the ICAO database, but are directly related to Fuel Flow data, so it is simple to obtain CO2 data using Fuel Flow data. In principle, if aircraft consume less fuel, there is also less CO2 emissions. Fuel Flow data show that newer engine generation installed at Boeing 737 MAX 8 (eg LEAP 1B27) or Airbus (LEAP 1A26 or PW1127G-JM) uses less fuel and consequently has lower CO2 emissions.

However, comparing the new Boeing 737 MAX 8 engine (LEAP 1B27) and the Airbus A320NEO (PW 1127G-JM), we come to the data that the Boeing LEAP engine needs about 60 kg more fuel for one LTO than Airbus A320NEO with its PW engine or 30 kg more fuel if we compare with the Airbus A320NEO equiped with LEAP 1A26E1 engine. Accordingly, the Boeing 737 MAX emits more CO2 emissions than its competitor Airbus A320 NEO (both engine versions).

 

NOx emissions

The third step and I am almost certain the most important one, that will determine the future of Boeing is the NOX emission. The LTO cycle was again taken as a reference point.

Comparing the NOX emission LTO cycle of the new Boeing 737 MAX 8 and the older version of Boeing 737 NG, we find that the Boeing 737 MAX 8 (LEAP 1B28) has NOX emissions about 12% higher than the older version of the Boeing 737 NG (737-800 with CFM56-7B27). In other words, the new generation of Boeing 737 has a higher NOX emission of about 12% than the older Boeing 737 NG generatin.

It has been heard many times in the automotive industry that this is actually quite normal that by reducing noise and CO2, NOX emissions increases.

But whether this is actually the case is best seen in the example of the Airbus A320 NEO.

Airbus A320 NEO equipped with LEAP engine, has about 49% lower NOX emissions than the older version of Airbus A320 CEO equipped with IAE engines.

If we look at the absolute figures between the Airbus A320 NEO and the Boeing 737 MAX 8, the Airbus emits 2852 grams of NOX per LTO, while the Boeing 737 MAX8 emits 6719 grams per LTO, which is a huge difference of almost 2.5 times.

It is difficult to explain why the Boeing 737 MAX 8 has so much worse environmental characteristics than its biggest competitor Airbus, even when they are equipped with engines from the same manufacturer (LEAP).

As I have already stated, the prices of take-offs and landings at many Western European airports already depend on the environmental characteristics of the aircraft (emissions), and I am almost certain that in the near future this will become the standard.

The above data clearly confirms that the Boeing 737 MAX 8 has a higher noise level, higher CO2 emission and much higher NOx emissions, compared to the main competitor.

How much and whether Boeing 737 MAX users will ultimately have to pay higher take-off and landing charges, whether airports will prefer Airbus, and how much this will affect the operation of Boeing 737 MAX and its cost-effectiveness and sustainability, there is no answer yet.

EU demands that airport charges should be transparent and non-discriminatory, but will Boeing 737 MAX users be discriminated in this case, even though the data obtained are based on official measurements?

We have no choice but to wait and see how uncertain the future of Boeing 737 MAX really is, and all indications are that it will be uncertain and certainly interesting.