Noise Abatement Procedures set out by the International Civil Aviation Organisation and low flying aircraft on departure from Heathrow

On departure there are two noise abatement procedures where a stepped departure climb is being used. They are called “NADP 1” and “NADP 2” (Noise Abatement Departure Procedure). 1 is used where there are noise sensitive areas close to the airport and 2 is used to alleviate noise in an area further away, say 25 kms+ from the start of roll on the airport runway. The restriction to two noise abatement departure procedures was agreed at the ICAO in order to minimize confusion internationally at the appropriate procedure to use for the lessening of noise for people on the ground.

Essentially the two noise abatement procedures are:

NADP 1: Aircraft to climb to 800’+ and then reduce thrust. Keep flaps lowered in take-off mode and continue climbing as fast as possible to 3,000’. Then retract flaps, increase thrust and go on your way

NADP 2: Aircraft to climb to 800’+ and then reduce thrust. Withdraw flaps at that  point and continue at a decreased rate of climb until 3,000’. Then increase climb and thrust and go on your way

The profiles look like this (illustration reproduced from Heathrow document Airline Survey Questionaire 2016):


A graph from the CAA document CAP1191 compares the various airlines and shows BA using a NADP2 type procedure against smaller other airlines using an NADP1 type procedure:

It can be seen by about Twickenham to the east or Englefield Green / Windsor/ Virginia Water to the west that a BA 787 is almost 2,000’ lower than an Ethiopian Airlines 787 or an Air India Airlines 787. The difference in noise caused by this 2,000’ difference is enormous.

A section from the ICAO Document 8168 describing the two noise abatement departure procedures is set out at the end of this article. There is also an arrivals procedure which includes the delay of bringing down flaps and landing gear but that will be dealt with in another article.

Notwithstanding that the ICAO make a clear recommendation that the different procedures should be used in different circumstances, Heathrow state that “One procedure would not necessarily have a better noise impact than another. Instead, changing from one procedure to another may redistribute noise from one location to another, resulting in both noise decreases and noise increases”[1]. The ICAO have published research which indicates that the contrary is true. The ICAO research paper Doc 9888 sets out details of some 25 surveys. Some are on arrivals and some are on departures. The results indicate that there is a difference of 2 – 9 dB between NADP 1 and 2 close in (research at Tokyo airport). That is to say that NADP 1 is between just under twice to three times quieter on departure than NADP 2 for people close to the airport.

In a recent Freedom of Information Act response from both the DfT and the CAA, they both say that “It is important to note, however, that no conclusions have yet been reached from this work, which is still ongoing”. Clearly Heathrow’s statement that noise is just re-distributed is disingenuous.

The ICAO acknowledge that there is more research to be done but they are clear that the two procedures are not so similar that “one does not have a better noise impact than another”. Clearly NADP 1 confers substantial benefits to residents close by the airport. Even on Heathrow’s illustrations the NADP 2 departing aircraft will not have caught up with an NADP 1 departing aricraft until at least 24 kms from start of roll. The levels beyond, as demonstrated by the Heathrow diagram above, show that the NADP 2 departing aircraft is marginally higher from some 24 kms from start of roll, but by then both planes are higher and the noise is less intrusive. In any case the ICAO say nothing of the NADP 2 departing plane climbing faster than the NADP 1 further out from the airport. None of this is new. The ICAO published its document 8168 setting out the two procedures and recommendatons in 2006.

Airlines operating out of Heathrow (an airport of acute noise sensitivity close by) are not required to use any specific noise abatement procedure apart from the attainment of the very bare minimum set out in the Heathrow Airport-London (Noise Abatement Requirements) Notice 2010. This is contrary to the Aeronautical Information Publications (AIPs) of any other airport in Europe, which provide detailed requirements for departure. Indeed, both the CAA and the DfT have stated in response to Freedom of Information Act questions that neither body has any idea of which airlines use which departure procedure out of Heathrow and why. In other words, there is a complete abdication of responsibility and the airports and airlines are able to operate what amounts in effect to a free for all regardless of the environmental consequences.

Many aircraft are using a form of the NADP 2 procedure out of Heathrow and one of the main users of the NADP 2 procedure is BA. Amongst other sources, this is confirmed by the CAA in their document CAP1191 on the departure profiles of the Boeing 787. The NADP 2 procedure at an airport like Heathrow is contrary to the recommendation and guidance of the ICAO. Heathrow and the CAA should not be allowing the NADP 2 type profile to be used at Heathrow airport if they are to comply with the requirements of the ICAO. From the diagram, it can be seen that the difference in height is at its greatest at some 12 – 13 kms from the start of roll of the departing aircraft – Teddington and Twickenham. To the west the most affected areas are Slough, Windsor, Englefield Green, Woodside, Cheapside, Virginia Water. The difference in height at 12 – 14 kms from start of roll between NADP 1 and NADP 2 is likely to be between 1,000’ and 2,000’. This will make a huge difference to the noise and environmental impact of a departing plane – yet neither Heathrow nor the CAA have said anything about this, rather simply saying “One procedure would not necessarily have a better noise impact than another”.

Research by TAG has shown that on a single day, within 30 minutes of each other, one long distance plane got to 4,000’ by 12 kms from start of roll while another at the same distance got to only 2,000’ (higher to Lahore, lower to Johannesburg). As both were long haul planes flying on the same day, variables like fuel load or air density were very unlikely to be relevant.

The lower flying of NADP 2 causes more harmful toxic NOx emissions according to both the UK Government and its Aircraft Noise Management Advisory Committee. According to the European Environmental report of 2016 from the European Environment Agency, this is getting progressively worse. The report states that:

“In 2012, aviation represented 13% of all EU transport CO2  emissions, and 3% of the total EU CO2 emissions. It was also estimated that European aviation represented 22% of global aviation’s CO2 emissions. Similarly, aviation now comprises 14% of all EU transport NOx emissions, and 7% of the total EU NOx  emissions. In absolute terms, NOx  emissions from aviation have doubled since 1990, and their relative share has quadrupled, as other economic sectors have achieved significant reductions”.

On noise and CO2 the European Environmental Report says “emissions and noise exposure in 2014 are around 2005 levels. Future improvements are not expected to be sufficient to prevent an overall growth in emissions during the next 20 years”. The industry has committed itself to keeping emissions at 2005 levels by 2050.

Heathrow themselves seem not to mention NOx, confining themselves to CO2 in their “Airport Reporting Criteria”. It appears that for NOx, Heathrow simply rely upon the certification of the of the ICAO’s internal Committee on Aviation environmantal Proection (CAEP). Using NADP 2 locally does not alter the certification on NOx.

So why is NADP 2 being used when it should not be used?

The answer is likely to be engine maintenance costs and fuel consumption. By retracting flaps at 800’+, the air resistance is reduced and less fuel is consumed. Our lives under departure routes are being made a misery not because it is necessary for the good of others who need to travel but because of money savings to be had by the aviation industry. Not only that; the UK is unique in this level of suffering since our European friends insist on the recommended procedures being followed. Their planes climb at a far greater rate than out of Heathrow – see the Teddington Action Group article on our website (which can be viewed by clicking here).

A technical presentation by the CAA to ANMAC (the Government’s Aviation Noise Management Abatement Committee) stated of the experiment at Brussels to reduce noise by increased climbs that:  “The marked difference in the average climb profile between the airline’s normal NADP2 procedure at Stansted and the current NADP1 procedure at Brussels is illustrated for information in Figure 7. It should be noted that the airline’s decision to initiate cutback to climb thrust at 2,500 feet, rather than 1,500 feet, in order to reduce noise at Brussels airport (at specific monitoring points under the flight path) would almost certainly result in an increase in the airline’s operating costs (engine wear, fuel burn, etc)”. That sums up the Aviation Industry and their lack of responsibility admirably.


[1] Heathrow Airline Survey Questionnaire by Mike Glen

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  1. Mahmoud
    7th January 2023

    Hi, I believe that there’re few vital contradictions as well as overlooking other facts in this article.
    1- reducing engine power at early stage as in NADP B or 2 as mentioned in this article, it doesn’t save engine life only but reduce fuel consumption as well. It’s obviously better as increase engine life that to say reduce the need for maintenance check which reduce materials consumption which ECO target. On the other hand, reducing power means reducing Fuel consumption “less pollution emissions”, very obvious however, it has been used in a negative sense!!
    2- NADP 2 or B is allowing to acceleration earlier, what that means? Less time passed over noise sensitive points or area which means less exposure to noise. To make it more clear, noise isn’t only the value of noise pollution production but it’s as well the Time of exposure

    • 7th January 2023

      Thank you for your comment. This line of argument is familiar to us and is put forward by both Heathrow and the CAA. It is a false argument as anyone living under or near a flight path can testify to. It is also disproved by To70 in their report as set out in the main article.
      Firstly the ICAO specifically recommend a higher rate of ascent in noise sensitive areas near the airport. Heathrow fail to abide by this guidance.
      Secondly, both NADP1 and NADP2 require a power reduction at the same moment. We in the communities around the airport are not offering ourselves as sacrificial lambs to afford a saving in maintenance costs to the airlines.
      Thirdly, the To70 report showed that the savings in fuel consumption were marginal and out of all proportion to the suffering inflicted by low flying.
      Fourthly, the concept of shortening the length of the noise by lower flying so as to benefit residents underneath is false. The disturbance, particularly late at night comes from the sound pressure levels (the maximum level of decibels emitted). Doubling up the loudness for every extra second through the SEL noise metric, so as to get a greater reading with a lower sound pressure level does not get an accurate result in assessing the suffering of the residents from the noise emitted
      Fifthly, the Heathrow Airport – London (Noise Abatement Requirements) Notice which requires that “aircraft shall at all times be operated in a manner which is calculated to cause the least disturbance practicable in areas surrounding the aerodrome”. Low flying singularly fails to do this.

  2. Nikolaj
    24th October 2022

    Is there any difference f.x between NAPD 1 and NAPD A in Europe?

    Thank you)

    • 25th October 2022

      Yes we believe that there is a difference and that NADP A is no longer in use (but stand to be corrected). NADP1 requires take-off thrust to be used until at least 800′ and thereafter a thrust reduction with flaps down until 3,000′. NADP A required take-off thrust to be used until 1,500′ and then a thrust reduction with flaps down until 3,000′

  3. Tim Walker
    7th September 2018

    good morning from South London. Excellent article. We are more affected here by noise from arriving aircraft from Heathrow (about 3500ft) on westerly operations and London City (about 1800 feet) on easterly operations, often both at the same time. I can find no references to Noise Abatement Arrival Procedures. Have you anything/references that can help?

  4. Katoe
    22nd August 2017

    Thank you for such a useful report. What can we do about it?
    Additionally, East Molesey MP recently wrote to Heathrow saying the just ‘three’ residents in his constituency were concerned about noise. This is untrue. We have no confidence in his ability to defend our rights…

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