A Review of the Current Regulatory Framework for Supersonic Civil Aircraft: Noise and Emissions Regulations

Round 1

Reviewer 1 Report

This manuscript presents a thorough and comprehensive review of noise & emissions regulations pertaining to supersonic civil transport aircraft. The authors have done a great job of organizing this manuscript, which is not always easy for such a topic. The important gaps in regulatory frameworks have been identified and explained effectively.

I have the following minor formatting comments -

1. The draft I received for review did not include any reference numbers in the body of the text. The missing reference numbers create some strange punctuations such as "... procedures , , . For details, see Chapter 6." on line 152. I request the authors to kindly check that reference numbers are properly rendered in the final version of the manuscript.

2. The standardized LTO cycle mentioned in lines 352-355 and lines 378-382 may be better presented as tables instead of bullet lists. 

Author Response

Reviewer 1

Comments and Suggestions for Authors

This manuscript presents a thorough and comprehensive review of noise & emissions regulations pertaining to supersonic civil transport aircraft. The authors have done a great job of organizing this manuscript, which is not always easy for such a topic. The important gaps in regulatory frameworks have been identified and explained effectively.

The authors would like to thank the reviewer for the valuable comments and endorsement.

I have the following minor formatting comments -

1. The draft I received for review did not include any reference numbers in the body of the text. The missing reference numbers create some strange punctuations such as "... procedures, , . For details, see Chapter 6." on line 152. I request the authors to kindly check that reference numbers are properly rendered in the final version of the manuscript.

Thank you for spotting the problem. We have checked and the problem do only appears when compiling the pdf. We will try to find out a solution with the help of the editorial staff.

2. The standardized LTO cycle mentioned in lines 352-355 and lines 378-382 may be better presented as tables instead of bullet lists. 

Thank you for this suggestion. We have improved the readability of the text by adding Table 1 combining both items.

Reviewer 2 Report

The only overall recommendation for the article - is to be reduced. It is a review of the status conditions, which is looking good for the report on the same subject, but not good for the scientific article. A large quantity of information is well-known for the specific auditorium, including historical aspects of the ICAO SARP, and its analysis is not used by the authors for any recommendation according to the new SST - some gaps are shown but what are the recommendations to cover them? Even in the Conclusion chapter there are a number of questions - not the answers.

If the general rules that have been developed for subsonic transport are applied to SST, inconsistencies may arise. They can cause the impossibility of implementing the standards by new SSTs and, as a result, disrupt the balance that was achieved by these standards in relation to subsonic aviation.

In my understanding, if specific standards need to be introduced in relation to new SSTs, for example for CO2 standard, then only be based on the condition of maintaining the established balance (in accordance with the balanced approach of ICAO), or justifying the new balance based on the need to implement SSTs in practice.

In any case, the article needs to be refined in terms of brevity, shortening and providing at least a couple of answers to the questions in the conclusions. 

Author Response

The authors would like to thank the reviewer for the work and the comments. The authors have tried to implement the suggestions related to the shortening of some wordy parts of the text. As far as the possibility of giving answers to the highlighted open points, the authors are involved in international discussions currently on-going at different levels including ICAO. Unfortunately, when the discussions are on-going, results cannot be revealed without breaching confidentiality restriction. We have included a remark in Section 1 highlighting this. However, the authors have tried to provide at least indications on the current research activities performed in the H2020 MORE&LESS project to find solutions for the arisen questions.