Heathrow ranks airlines’ emissions and night noise performance

The 50 busiest airlines at Heathrow will now be publicly ranked on their work to reduce emissions and noise in their operations. Every three months, Heathrow will publish its new Fly Quiet and Clean League Table showing a red/amber/green rating for seven noise and emissions criteria. 

The new league table is an expanded version of the successful Heathrow Fly Quiet programme, which has tracked airlines’ noise performance since 2013 and incentivised airlines to use their quieter aircraft types and operating procedures at the airport. It adds two emissions-based criteria which scores the type of engines used by aircraft (the ‘CAEP’ score) and the efficiencies of aircraft when it comes to NOx emissions per seat (the ‘NOx/seat’ score). 

As part of the airport’s efforts to reduce the number of aircraft operating at night, and to provide more predictable periods of noise respite for local residents, the new table also includes a new metric tracking unscheduled airline operations between 11:30 at night and 4:30 in the morning.

The first Fly Quiet and Clean League Table, based on data from January to March, reveals British Airways’ short haul, Aer Lingus and Etihad Airways as the cleanest and quietest fleets at the airport. 

The Fly Quiet and Clean Table is part of Heathrow 2.0, the airport’s new sustainability strategy, which aims to make Heathrow the world leader in delivering the cleanest aircraft and operations possible, targeting emissions in several ways: 

• On arrivals: by linking our landing fees to an aircraft’s NOx emissions. In 2017 we increased this fee by nearly 100%.
• On the airfield: by encouraging airlines to use reduced-engine taxiing
• At gates: through £20-million-pound investment in technology like pre-conditioned air so aircraft can turn their engines off. This year, we are aiming to increase the use of this technology by 20% compared to 2016.
Matt Gorman, Heathrow Director of Sustainability said:

“While the main contributor to local pollution remains road traffic, Heathrow is playing its part to improve air quality by reducing emissions from its vehicles, buildings and aircraft. We are excited to add a whole new dimension to the league table and have another tool to help airlines to reduce their impact on air quality. Together, we can play our part to improve our local environment and help the UK and London governments meet their air quality targets.” 

By publishing the table each quarter, Heathrow aims to recognise good performance, provide airlines with regular feedback, and identify specific areas to be targeted for improvement. Heathrow will engage with airlines showing red results in the latest league table to improve their rating.

The position of an airline in the league table is determined by the overall score figure. The higher the overall score is the better the position is in the league table. The overall score can be a number between 0 and 1000. The final score for each airline is calculated by adding up combinations of an airline’s ranking position for each individual metric and the weighting set for the given metric. This means that in order to get a ‘perfect’ overall score of 1000 an airline would have to be ranked #1 in all metrics across the board; conversely to score a 0 an airline would have to be ranked #50 in all metrics in the programme. The amount of points deducted from the ‘perfect’ overall score depends on the weighting of individual metrics; for example ranking #5 in Continuous Descent Arrivals (CDA) metric will mean more lost points than ranking #5 in Noise Certification metric due to higher weighting associated with the CDA metric (150%) than the weighting associated with the Noise Certification metric (50%).

The 7 metrics explained:

Each metric is assigned a “RAG” (Red, Amber, Green) status based on the performance bands set for that indicator. As a result operators towards the top of the table will typically have more ‘green scores’ than those towards the bottom. Individual metric scores will not be published.

Where the table shows amber dots, the airlines have met Heathrow’s minimum performance targets and green dots show they have exceeded them. If the airline has a red dot in a particular area, we work closely with them to improve performance.

1. Noise quota/seat 

This is a relative noise “efficiency” metric which scores the noise efficiency of an operator’s fleet, recognising that whilst larger aircraft tend to be noisier they also carry more passengers. It is calculated by dividing the sum of quota count points (QC) for arrivals and departures by the aggregate seat capacity. Just like all other metrics, the product of the calculation described is divided by number of movements; this provides a balance between a QC/seat or QC/movement metric which will tend to overly bias long haul or short haul carriers respectively.

1. Chapter number (noise certification)

Each aircraft is required to have a noise certificate which can be used to determine its relative performance against ICAO noise standards called Chapters. This allows us to recognise “best in class” and compare performance across different fleets that airlines operate on their flights to and from Heathrow. In the first step, a ‘nominal’ Chapter number score is assigned on the basis of the certification of the aircraft associated with each individual flight, using the scoring mechanism as shown in the table below. In the second step, in order to account for the increased sensitivity of neighbouring communities to noise in the evening and night hours, a time adjustment factor is applied to the ‘nominal’ Chapter number score for flights operated in the evening period (between 19:00 and 23:00 local time) and in the night time period (between 23:00 and 07:00 local time), as explained below. Using these principles we favour airlines that operate modern, quieter aircraft.

For more information on Chapter number charging categories please refer to Heathrow’s Conditions of Use (visit heathrow.com and search for “Conditions of Use”).

Chapter number 3 4 High 14 Base 14 High 14 Base 14 Low Nominal points 8 4 2 2 1 0.5

The points above are adjusted by a factor of 1.5 and a factor of 2 for evening (19:00-23:00 local time) and night (23:00-07:00 local time) periods respectively.

1. NOx emissions/seat

This is a relative emissions “efficiency” metric which is in many ways similar to the noise quota/seat in the noise metrics set. For each arrival and departure we calculate the total mass of NOx emissions, based on the certified values and accounting for the number of engines for the aircraft associated with individual flights. The aggregate of certified NOx emissions for all flights of an airline are then divided by the aggregate seat capacity.

1. CAEP Standard (engine emissions certification)

Each engine has to be certified against the emissions standards produced and published by the ICAO’s Committee on Aviation Environmental Protection. This allows us to recognise the use of clean technology by giving better scores to aircraft that are compliant with the more recent and more stringent CAEP standards. Taking into account the specific aircraft associated with each arrival and departure, we determine the CAEP standard compliance and assign a specific score against each flight based on the table below. The score is based on the certification value for a single engine, which means that a twin-engine aircraft the engines of which are compliant with CAEP 6 standard gets the same score as a quad-engine aircraft the engines of which are compliant with the same standard.

CAEP standard pre-CAEP 2 4 6 8
Points 16 8 4 2 1
1. Continuous Descent Approach (CDA) violations 

CDA involves arriving aircraft maintaining a steady angle of approach during the descent towards the airport, as opposed to a stepped approach which involves periods of prolonged level flight. This reduces noise because it requires less engine thrust and keeps the aircraft higher for longer. By following a CDA on arrival, the noise on the ground can be reduced by up to 5dBA in areas away from the final approach paths. The purpose of the indicator is to capture the non-CDA arrivals and so potentially reduce the disturbance caused.

1. Track keeping (TK) violations 

A. ircraft are required to stay within the corridors of ‘noise preferential routes’ (NPRs) – 3km-wide corridors in the sky, designated by the Government to route aircraft away from more densely populated areas as far as possible – until they reach 4000ft above mean sea level. The track deviations indicator is expressed as the proportion of departures that flew outside the NPRs below 4000ft. The purpose of the indicator is to capture the aircraft which operate outside of these boundaries and so potentially cause unexpected noise disturbance. Instances where this occurs for reasons outside of the airline’s control are excluded for the calculation.

1. Early or late movements between 23:30 and 04:30 

A. his metric focuses on flights that take place during the time period within which the neighbouring communities are most sensitive to aircraft noise. For the purpose of this metric, we count the night flights that have operated between 23:30 and 04:30 local time and have not been granted a dispensation (e.g. due to medical emergency) and that are not exempt from the night quota system.

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