Future noise standards, effective from 12/31/2017, puts the current noise level down by 7 EPNdB (equivalent perceived noise in dB). Now, what does that mean? Will we see less noisy aircraft in the future as we would have seen without that new regulation? Will aircraft and engine companies have to put more resources to optimize the aircraft/engine system regarding noise levels? Let's have a look at a chart that was published in the "ICAO Environmental Report 2010":
The report states that these values of noise levels relative to Chapter 3 represents "today's best practice aircraft" to "understand the current state-of-the-art (...) aeroplane noise technology."
The current Chapter 4 is 10dB below Chapter 3, so the proposed Chapter 5 would be -17dB in the chart. As we can see, the only aircraft type that is marginal relative to Chapter 3 -17dB would be the "Short and medium range jets with two engines", i.e. the A320/B737 category (in the future also CSeries, C919, MS-21).
According to the french noise certification database, the B737-900ER certified as of today has a margin relative to Chapter 3 of 11.7 EPNdB (highest -900ER MTOW version). Therefore it would not be compliant with Stage 5, missing the target by 5.3EPNdB. The A321 as the member with the highest MTOW of the A320 family would also miss the new standard, showing 12.8 EPNdB margin (with V2533-A5) resp. 11.6 EPNdB (CFM56-5B2/3). But that does not mean you can't fly these aircraft anymore in 2018. It does not even mean you can't sell/by them after 12/31/2017. The new standard only affects aircraft/engine combinations certified after that date. But by that date all A320neo variants and the B737MAX ( at least the first variant, either the -8 or the -9) will be certified - at least that is the plan of the manufacturers. These aircraft are marketed by the manufacturers as to be 15-20 EPNdB below Stage 4, so that would be 8-13dB below the new Stage 5.
There is another chart in the ICAO report from 2010, showing what independent experts thought would be achievable by 2018 (when Stage 5 comes into play) and in 2028 (Stage 6?).
The goal for the A320/B737 category then was Stage 4 -21+/- 4.6 EPNdB, so the minimum goal was Stage 4 -16.4 EPNdB. The new regulation now calls for Stage 4 -7 EPNdB. To say it clear: this is no regulation at all, this just showing what has been state-of-the-art before.
As for the A320/B737 category, the real successors (A30X, B797?) are maybe 15-20 years away so they would probably affected by a Stage 6 regulation (if that would be any). The chart above now can give us an indication where Stage 6 could be. As the 2018 minimum goal was reduced by almost 10 EPNdB and the 2028 minimum goal was -(23.5-5.5)EPNdB = -18 EPNdB I could imagine we will see a further reduction of 5-7 EPNdB, so that Stage 6 would be 12-14 EPNdB below Stage 4. This is what A320neo and B737MAX (and their engines) will have achieved by 2017 anyway. Ridiculous I say! Airports all over the world should cry foul immediately - and airlines with them. Look at Europe in particular: Munich does not get a 3rd runway in the next few years, Heathrow will probably never get one...and why: it's all over noise! If ICAO does not get proactive on the noise issue, growth will be prohibited in the future.
The only reason I see for these new regulations is the hope for an Open Rotor to get certified on day. All experts say (at least until today) that an Open Rotor can not be less noisy than today's turbofans (like CFM56 and V2500), so any future strict regulation would prohibit the Open Rotor from the beginning. But the hope for an Open Rotor to become a viable alternative for the generation of advanced and geared turbofans now in development is fading anyway - if you talk to airport managers, they will tell you about it...
An opportunity for a future path of growth in aviation, accepted also by the public, was missed - let's hope for the next one!
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