Monitoring Gatwick s promises: Air traffic over west Tunbridge Wells

Transcription

1 Monitoring Gatwick s promises: Air traffic over west Tunbridge Wells December 2013 to July 2017 Langton Green Rusthall Tunbridge Wells Photo: Langton Green, May 16, 2016, 06:57 EBC 8/17

2 Contents Background and the Gatwick Arrivals Review: Overview and Final Action Plan 3 Report card: one year on 4 The arrivals swathe and populations affected 5 Aircraft noise 9 Key items from the Arrivals Review: The Airbus whine 13 Continuous Descent Approach (CDA) 15 Pre-2013 conditions and fair and equitable dispersal (FED) 20 Spill-over into night time 27 A simplified view for managing the swathe 33 Comments 38 2

3 Background In 2013 Tunbridge Wells was surprised by a several-fold surge in overflights headed for Gatwick Airport. A flight stabilisation initiative caused the lengthening of Gatwick s final approach path by three nautical miles. Following public outcry*, in June 2016 Gatwick Airport published an Overview and Final Action Plan**. Departing aircraft Gatwick Tunbridge Wells Arriving aircraft Snapshot showing 4 hours of flightpaths around Gatwick Airport and the final approach path *For more information visit, for example: and campaign groups and ** ivals-review/gatwick-airport-arrivals-review-final-action-plan-01june2016-final-copy.pdf. 3

4 Report card: one year on*... still a long way to go Action Plan ref. Summary description Slide nos. Progress at July 2017 Comments Imm-01 The Airbus A320 whine Elimination by 31 December 2017, or penalties thereafter. 13 Significant progress: aircraft with whines divided by four. Imm-06 Imm-07 Continuous Descent Approach (CDA) Improved performance from 8,000 feet. [This implies descent angles closer to 3 0, per established international best practice.] No progress. Descent angles continue to be half what they should be. Average altitude is 1,000 feet too low. Altitude variation remains excessive. Imm-10 Pre-2013 conditions and fair and equitable dispersal (FED) Minimum final approach join-point reduced from 10 to 8 nautical miles (nm) to more closely emulate pre-2013 conditions and support a fair and more equitable dispersal Negligible progress. The reduction to 8 nm was carried out in Oct The swathe peak position was marginally improved for a few weeks only. Dispersal remains unfair and inequitable. Imm-12 Less spill-over into nights. Reducing unplanned night arrivals (i.e. from 23:30) Out of control. 40% of arrivals during the first hour were spillovers during June-July *For a precise reading of actions, objectives and accompanying information, see: als-review/gatwick-airport-arrivals-review-final-action-plan-01june2016-final-copy.pdf. 4

5 The arrivals swathe and populations affected 5

6 The swathe of westerly flights headed for Gatwick Departing aircraft The westerly approach to Gatwick is the busiest Gatwick: Capacity of up to 55 movements (i.e. landings plus arrivals) per hour Tunbridge Wells Crowborough Arriving aircraft The westerly approach is used when prevailing winds are westerly, i.e. coming from the west (on average 7 days out of 10). Source: CASPER 4-hour delay screenshot taken 14:00, August 5,

7 MAY-R004 flightpath** The swathe of westerly flights headed for Gatwick (2)* Departing aircraft More people affected by noise since 2013 Gatwick Runway 26 6 nm 8 nm 10 nm Tunbridge Wells Crowborough Arriving aircraft Sources: *CASPER 4-hour delay screenshot taken 14:00, August 5, **MAY-R004 flightpath in case of no ground radar, from CAA map ref. AD 2-EGKK-7-12 Feb 4, In 2013 Gatwick Airport increased the minimum join-point to its final approach path from 7 to 10 nautical miles, pushing arriving flights eastwards over Tunbridge Wells and surrounding areas. 7

8 Populations affected by at least 50% of aircraft noise level 70,000 more people affected by flightpaths further east 2 46, , , ,542 Note: This shows that the 2013 flightpath change, in shifting flights eastwards, disregarded Government policy to minimize population affected. Sources: Population numbers: 2011 census by parish. The shadowed area approximates to the predominant flightpath swathe used by aircraft. 1. MAY-R004 = default flightpath when no radar, from CAA map ref. AD 2-EGKK-7-12 Feb 4, Flightpaths from FLIGHTRADAR24, am July 16, 2016: 2 = IBK5BV; 3 = AEA1013; 4 = EZY8416. *See graph page 51 from Gatwick Airport Independent Arrivals Review, January The average parish width is about 3 nautical miles i.e. the same as the width of a 50% aircraft noise level envelope*. Total population affected can therefore be estimated by adding up parishes crossed. 8

9 Aircraft noise Below: 1-minute sound recording taken under the flightpath of flight TOM92W crossing the A264 at Langton Green at 04:38 on July 7, 2017, clear sky. Aircraft type Boeing 737-8K5; origin Larnaca; altitude 5,081 feet; ground speed 229 knots; descent angle 1.37 degrees. Aircraft distance travelled = 3 nautical miles (18,228 feet) 9

10 Aircraft noise level Table 4: Human perception of differences in noise level (decibels) [3] 3 db just perceptible 6 db clearly noticeable 10 db half as loud Aircraft are too noisy for night time use Examined swathe line 3 db Just perceptible Human perception of differences in noise level (decibels) 6 db Clearly noticeable 10 db Half as loud (1.5 nautical miles away at altitudes around Tunbridge Wells) Sources: *Adapted from DOT January 2017 night flights restrictions consultation document, page 70. **WHO (World Health Organisation) Night Noise Guidelines for Europe (2009). According to the World Health Organisation (WHO), people indoors trying to sleep within an outside noise envelope of 61 decibels are likely to suffer sleep disturbance**. 10

11 Frequency of audible noise at the centre* of the swathe July 2017 (68% of noise events occur within less than 4 minutes) No change. Noise events remain too frequent Average July (66% of noise events occurred within less than 4 minutes) Note: Noise lasts for up to one minute on each occasion. Minutes between aircraft Audible noise events (i.e. aircraft within 1.5 nautical miles) July 2015 July 2016 July 2017 % of noise events occurring within less than 4 minutes 63% 69% 68% Average time between successive events (minutes) Source: *FLIGHTRADAR24: Aircraft crossing a central 5 km stretch of the swathe. 70 flights from random 1-hour samples from each of: Dec-13, Nov-14, Jul-15, Jul-16, Jul-17. **See graph page 51 from Gatwick Airport Independent Arrivals Review, January The central third of the swathe line is close to 3 nautical miles wide, i.e. the same as the width of a 50% aircraft noise level envelope at these altitudes**. A fair and equitable flightpath distribution would reduce noise event frequency. 11

12 Noise ranking Factors influencing noise level invasive Aircraft noise feels invasive from less than 9,000 feet. Aircraft distance is by far the main factor for noise slight nuisance Observation position Diagonal distance (feet) Factors compared to find best correlation (Aircraft exhibiting whines excluded) Lateral distance Altitude Descent angle Ground speed 176 to 9,712 feet (average = 5,179 feet) 2,850 to 5,500 feet (average = 4,402 feet) 0.2 to 3.8 degrees (average = 1.5 degrees) 201 to 246 knots (average = 220 knots) Aircraft type Airbus 320 family = 83% Sources: Aural comparison of smartphone recordings. Sorting for ranking using editing software. FLIGHTRADAR24 and CASPER: Sample taken , Sunday April 9, Distance, engine thrust, type of engine and wing configuration can all affect aircraft noise. 26 sound recordings were subjectively ranked in order of noise level. 12

13 The Airbus whine Action Plan reference Imm-01 Summary description: Elimination by 31 December 2017, or penalties thereafter. 13

14 The Airbus A320 whine Airline Boeing etc. no whine August 2016* July 2017** Airbus no whine Airbus with whine % Airbus whine Boeing etc. no whine Airbus no whine Airbus with whine % Airbus whine EasyJet % % British airways % % Norwegian n/a n/a Monarch % % Ryanair n/a n/a Thomas Cook % % Tomson n/a n/a Vueling % others n/a TOTAL % % Observation position Significant progress: whines divided by four August 2016 July 2017 Sources: *50 ground observations using CASPER to identify aircraft, 13:47-16:06, August 31, **50 ground observations using CASPER to identify aircraft, 10:34-13:09, July 7, The Airbus whine is due to a small feature under wings of older models of the A319, A320 and A321 aircraft family. Airlines, led by easyjet, are in the process of modifying or replacing their aircraft. 14

15 Continuous Descent Approach (CDA) Action Plan reference Imm-6-7 Summary description: Improved performance from 8,000 feet. [This implies descent angles closer to 3 0, per established international best practice.] 15

16 Stacking, meandering and altitude Note: A crowded sky above Tunbridge Wells, helping to push flights downwards 3 0 descent angle (international best practice) Need to liberate airspace and stack further out Flight UAE15, May 16, 2016 Descent angle Source: FLIGHTRADAR24: Samples taken May 16, Note: Meandered planes appear to arrive lower and with shallower descent angles (see next two slides) Distance travelled within a 40 km radius of join-point to final approach Vertical airspace over Tunbridge Wells is overcrowded. Due to frequent use of nearby stacking and meandering, Gatwick aircraft arrive at the swathe at lower altitudes and descent angles than at other airports. 16

17 Aircraft altitudes, central third of swathe July 2017 Av Altitude determined by international best practice of 3 0 descent angle Altitudes are too low. Altitude variation is excessive Altitude (feet)* Examples of altitudes less than 3,000 feet (should be 5,400 feet)** Dec 2103 Nov 2014 Jul 2015 Jul 2016 Jul 2017 Average hourly altitude variation (feet)* Altitude 2,804 feet Altitude 2,985 feet Sources: *FLIGHTRADAR24: Aircraft crossing a central 5 km stretch of the swathe line selected. 70 flights from random 1-hour samples from each of: Dec-13, Nov-14, Jul-15, Jul-16, Jul-17. **CASPER: Feb 28, 2017; Jul 17, Lower altitudes mean more noise. At a best practice 3 0 descent angle, average altitude should be 1000 feet (22%) higher. Large altitude variation means some aircraft are 35% lower than others. 17

18 How descent angles* compare with other airports To Gatwick RWY26** (at the A264 swathe line) To other airports*** (at similar altitudes) Descent angles are half those elsewhere Descent angle (degrees) Sources: *Angles calculated from horizontal and vertical speeds above the examined swathe line. **FLIGHTRADAR24: Aircraft crossing a central 5 km stretch of the swathe line. 70 flights from random 1-hour samples from each of: Dec-13, Nov-14, Jul-15, Jul-16, Jul-17. *** FLIGHTRADAR24: Jul 25-29, Readings taken at equivalent altitudes. Airports: ADL; AMS; ARN; ATH; ATL; BCN; CDG; DOH; DUB; DXB; FCO; FRA; GVA, HGK; JFK; LAX; LHR; LIS; MDW; NRT; OSL; SAW; SCL; SHA; SIN; SYD; TLV; VIE; VKO; YUL. **** See, for example, Basic Principles of the Continuous Descent Approach (CDA) for the Non- Aviation community CAA, 2007; Noise from Arriving aircraft: An Industry Code of Practice NATS, CAA et al *****Descent gradient = (Drag Thrust)/Weight. So a lower descent angle implies more thrust. Best practice advises a 3 0 descent for optimum noise reduction****. Shallower descent angles imply aircraft are flying lower earlier and are employing higher thrust***** (i.e. more noise). 18

19 Average speed (knots) Aircraft speed July 2017 Average Aircraft are now flying slower Speed in knots Dec-13 Nov-14 Jul 15 Jul 16 Jul 17 Note: Overall reduction in speed 2013 to 2017 Source: FLIGHTRADAR24: 70 flights from random 1-hour samples from each of: Dec-13, Nov-14, Jul-15, Jul-16, Jul-17. This is positive news. Higher speeds would tend towards the use of higher engine thrust (and therefore noise). 19

20 Pre-2013 conditions and fair and equitable dispersal (FED) Action Plan reference Imm-10 Summary description: Minimum final approach join-point reduced from 10 to 8 nautical miles (nm) to more closely emulate pre-2013 conditions and support a fair and more equitable dispersal. 20

21 Hourly flightpath variation Flightpaths appear haphazard +1 hour Bunched Bunched +1 hour Sources: Top: CASPER 1-hour screenshots, 12:00 and 13:00 September 5, Above: CASPER 1-hour screenshots, 20:00 and 21:00 September 27, Aircraft vectoring appears random. Hour-to-hour variations in position and concentration of flightpaths remain significant, even when overall activity is similar. 21

22 Hourly flightpath variation (2) Flightpaths appear haphazard +1 hour Bunched Bunched +1 hour Sources: Top: CASPER 1-hour screenshots, 22:00 and 23:00 May 29, Above: CASPER 1-hour screenshots, 20:00 and 21:000 July 20, 2017 Hour-to-hour variations in position and concentration of flightpaths continue today for no apparent reason. 22

23 Hourly total swathe variation W of Holtye Holtye W of Ashurst E of Ashurst Langton Green W Tunbridge Wells E Tunbridge Wells Pembury E of Pembury W of Holtye Holtye W of Ashurst E of Ashurst Langton Green W Tunbridge Wells E Tunbridge Wells Pembury E of Pembury Swathe varies haphazardly Equitable distribution Equitable distribution Sources: Left: CASPER 1-hour screenshots, May 20, 2017; Right: CASPER 1-hour screenshots, July 27, 2017 Swathe position and spread are both inconsistent. Hardly any swathe corresponds with equitable distribution. Why? 23

24 Bimonthly overflight distribution, west to east Note: Temporary shift of peak towards pre-2013 conditions, around November 2016 July 2016 July 2017 Examined swathe line No change. Unfair and inequitable distribution 1.5 nm ( 10dB, or a 50% drop in noise level) Source: CASPER 1-hour screenshots, flightpath locations visually counted. Sampling method: Only entire days when Runway 26 being used (i.e. wind from the west) 1-hour samples captured from 1 am to midnight 1st sample: 1st day of month when RWY26 being used 2nd sample: 4 days later, or 1st day after that when RWY26 being used 3rd sample: 4 days later, or 1st day after that when RWY26 being used 4th sample: 4 days later, or 1st day after that when RWY26 being used etc. Following a promised October 2016 decrease in minimum join-point from 10 to 8 nautical miles, flightpath concentration still remains peaked where there was little traffic before (Temporary respite in November 2016.) 24

25 Focus on the central third of the selected swathe line 5 kilometres, 2.7 nautical miles Langton Green Rusthall W Tunbridge W No significant change since late 2013 Average (above) July 2017 Source: FLIGHTRADAR24: 70 flights from random 1-hour samples from each of: Dec-13, Nov-14, Jul-15, Jul-16, Jul-17. The post-2013 peak remains over Langton Green, which had been relatively traffic-free prior to Note that differences in flightpath frequency are discernible over as little as 700 metres. 25

26 Positions of aircraft join-points to the final approach path Join-points Join-point analysis does not help Examined swathe line Note: There exists good pre-2013 data on aircraft joinpoint positions, but the diagram above shows that this does not necessarily reflect crossing point over the examined swathe line that affects west Tunbridge Wells. Source: CASPER 4-hour screenshot 16:00, September 1, The position of the joinpoint to the final approach path (at top) does not signify where the aircraft crossed the examined swathe line. The two are unrelated. 26

27 Spill-over into night time Action Plan reference Imm-12 Summary description: Reducing unplanned night arrivals (i.e. from 23:30). 27

28 Arrivals per hour Air traffic variation around the clock (summer) 35 Night quota period 23:30-05:59 Communities face a 24-hr exposure to noise Time of day Source: CASPER: Sunday 28 August, 2016, all flights into Gatwick. Aircraft perform several rotations per day. This can result in a rushhour at the end of the day due to accumulated delays, causing a spill-over into night hours. 28

29 Arrivals per hour Night flight frequency* Friday Saturday Sunday Noise heard 25% of the time around midnight BLUE: Audible from centre of swathe line** Note: Noise lasts for up to one minute on each occasion, so at 15 audible flights per hour, noise can be heard 25% of the time. Sources: CASPER: Sample taken August 5-7, * The night quota period is from 23:30 to 05:59. **See graph page 51 from Gatwick Airport Independent Arrivals Review, January Under the central third of the arrivals swathe there are over 15 audible flights per hour around midnight during the summer. 29

30 Number of arrivals Spill-over into the night quota period (23:30-05:59) Air Canada tyre incident, Jul 17, 2017 Spill-over is out of control Scheduled arrivals Spill-over arrivals Note: 79.6% of spill-over flights landed during the first hour of night quota period (23:30-00:29). Focus on the pm am rush hour April 2017 May 2017 June 2017 July 2017 Scheduled arrivals / hour Actual arrivals / hour Spill-over, % of actual arrivals 5% 14% 35% 44% Sources: from April 1, 2017, supported by and airline websites. Spill-over was especially high during June and July 2017 where, during the first hour of night quota period, 40% of arrivals were spill-over flights. 30

31 Arrival rate/hour Spill-over rate Analysis of spill-over arrivals* Scheduled arrivals 21:00-23:29 Spill-over arrivals after 23:30 Later schedules and easyjet are problems Scheduled time Scheduled time Scheduled mix Spill-over mix TOP: Too many arrivals are scheduled for the 22:30 to 23:29 time slot. Sources: from April 1, 2017, supported by and airline websites. *Analysis of scheduled arrivals from 21:00 to 23:29 only. LEFT: EasyJet accounts for a disproportionate number of spill-over flights. 31

32 Spill-over rate Analysis of spill-over arrivals* (2) Top 25 airports of origin (out of 112) Some airports are worse than others Sources: from April 1, 2017, supported by and airline websites. *Analysis of scheduled arrivals from 21:00 to 23:29 only. Some airports of origin are more associated with late arrivals than others. Madrid, Athens, Lisbon, Toulouse and Munich are the worst. 32

33 A simplified view for managing the swathe 33

34 Arrivals frequency at Gatwick The average gap between aircraft is 135 seconds Time between flights (seconds) Average = 135 seconds = 27 arrivals per hour 135 seconds provides 27 arrivals interlaced with 27 departures per hour for Gatwick s single dual-use runway. Source: *CASPER: 24-hour study September 23, 2016 (454 arriving flights timed crossing the M23). 34

35 A simplified view for managing the swathe - STEP 1 1. Establish a default flightpath position 10 nautical miles MAY R004 designated approach without radar STEP 1 The default flightpath position should be to the extreme west, for example as shown (overflying Holtye on the A264). 35

36 A simplified view for managing the swathe - STEP 2 2. Control the number of aircraft in the swathe Crowborough 3 aircraft: flights cross at Ashurst 5 aircraft: flights overfly east Tunbridge Wells Crossing points west to east according to number of aircraft in swathe No. aircraft north of Crowborough Time between aircraft (seconds) AVERAGE A264 road cross-point* Holtye Ashurst Langton Green/Rusthall East Tunbridge Wells Source: *CASPER: Analysis of 50 flights timed from Crowborough to Gatwick, am Feb 25, (The A264 road runs due west from Tunbridge Wells and corresponds with the examined swathe line.) STEP 2 The number of aircraft north of Crowborough should be variably controlled in order to be able to evenly disperse aircraft west to east. 36

37 A simplified view for managing the swathe - STEP 3 BAW2783 will cross the M seconds after RAM808 2 NAX34E will cross the M seconds after BAW Ensure aircraft turn on time 1 RAM808 crosses the M23 Correct flight path for BAW2763 Actual flight path for BAW2763 BAW2763 will cross the M seconds after NAX34E. AIRCRAFT TURNED TOO LATE 4 37 Source: CASPER: Sample taken 20:13, September 1,

38 Comments 1. One of the products of the Arrivals Review had been a Noise Management Board in which local communities and campaign groups participate. General concerns about the future include the following: Promised change is slow. With the forthcoming arrival of fixed flightpaths (PBN), for affected residents matters could get worse. PBN and other modernisations are expected to significantly increase runway capacity. Gatwick Airport could always get its second runway to further increase capacity. There is the ongoing danger of increased numbers of allowed night flights. New housing estates projected for west Tunbridge Wells will be under the peak of the flightpaths. 2. Monitoring was commenced after the 2013 changes, once noise became an issue. For various reasons retrospective data concerning the pre situation has not been available or too limited in scope to compare with the data presented in this report. 3. Websites that track arriving flights include: CASPER: or FLIGHTRADAR24: The use of both apps is required according to need. 4. In this report it is assumed, from subjective assessments, that invasive noise level from an aircraft will be experienced at up to 1.5 nautical miles (9,000 feet) from that aircraft. That distance roughly corresponds to a change of 10 decibels, i.e. half the noise level. The width of a noise envelope is therefore double that distance. 5. Clearly the first consideration is how close an aircraft is. Fair and equitable distribution implies that aircraft would be evenly spread out within the arrivals swathe south of the final approach path. 6. In the chosen swathe line used for analysis here (i.e. the line of the A264 road headed due west from Tunbridge Wells) the present swathe is up to about nautical miles wide. 7. A second consideration for communities concerns night flights. Gatwick Airport is presently allowed a night quota. In summer we see between 30 and 60 scheduled arrivals between pm and 5.59 am. 8. The third consideration relates to the aircraft itself and how it is flown. Some comments: If it is flying at a lower altitude it will be louder. If it is flying faster and/or more horizontally it will likely require more engine thrust and therefore be louder. International best practice recommends a Continuous Descent Approach (CDA) for noise abatement. Most major airports worldwide operate at an average descent angle of 3 degrees from 6-8,000 feet. Detecting inconsistencies in altitude, speed, and descent angle provides opportunities for improvement. The original Airbus A320 family has a feature under the wing that causes an unpleasant whine unless modified. Newer aircraft engines, such as the Airbus Neo, are as a rule quieter. The industry has ambitious targets for the future, and electric engines (when they arrive, anticipated in the 2030s) could hail even better noise levels. 38