AIRSPACE INFRINGEMENTS BACKGROUND STATISTICS What is an airspace infringement? A flight into a notified airspace that has not been subject to approval by the designated controlling authority of that airspace in accordance with international and national regulations. Such airspace is considered to be: Controlled airspace, namely ICAO airspace classes A to E. Note: VFR traffic cannot infringe Class E airspace because under ICAO rules neither an ATC clearance nor a radio communication is required to enter or operate within it, unless filed national differences call for one or the other (or both). IFR traffic can infringe Class E airspace when not in receipt of a clearance to enter it. Aerodrome Traffic Zones, where these exist in Class G airspace. Airspace restrictions, such as: Prohibited, Restricted and Dangers Areas, Temporary Reserved Airspaces or airspace notified by a restriction of flying in accordance with national requirements. Who infringes? All sectors of the aviation community - commercial, military and GA alike - are associated with airspace infringements. Infringement reports submitted to the CAA through the Mandatory Occurrence Reporting (MOR) scheme (see below) - form the basis of infringement statistics to which the CAA and the Airspace Infringement Working Group (AIWG, see below) will refer in the course of their work. Although it is recognised that many infringements are resolved on the spot, these may go unreported and therefore may not form part of the official statistics. How often do infringements occur? Statistically, roughly three infringements occur every couple of days. The majority are attributable to GA pilots and most, but not all, involve controlled airspace - primarily Control Zones (CTRs) and Control Areas (CTAs) serving airports and also TMAs and Airways. Those occurring outside controlled airspace tend to involve Aerodrome Traffic Zones (ATZs) and Danger Areas. Infringements of Restricted Airspace (Temporary) (RA(T)) associated with air shows or Red Arrows displays (often both) also feature. Infringements occur throughout the year, but there is a clear seasonal variation as to when they occur. Unsurprisingly, peaks are traditionally associated with the summer months good VFR conditions encouraging more pilots to fly, sheer numbers alone increasing the probability of infringement with troughs emerging with the onset of autumn and winter. The arrival of spring brings with it a steady monthly rise in reported infringements, leading to again to the annual summer peak. Where do infringements occur? Some airspaces are more infringed than others. Why? Several factors come into play. Most infringements occur in southern England and so can be attributed to more congested skies and a complex airspace structure. Another factor which should not be overlooked is the impact major air events can have on the scale and pattern of infringements; RA(T)s protecting these are infringed despite the best efforts of event organisers and the aviation community in general to make pilots aware of their establishment. Sheer weight of numbers
of VFR aircraft flying to and from such an event can lead to a number of infringements of adjacent controlled airspace, danger areas and the like by participating aircraft. Furthermore, external factors such as the 2001 foot and mouth crisis and the immediate effects of September 11 2001 can curtail aerial activity (and thus the probability of infringement) or heighten awareness and observation of infringements from a security perspective. It is not clear whether current economic conditions are influencing flying rates and therefore the probability of infringements; evidence from certain quarters suggests reductions in some activities, whereas other sources suggest no change at all. Finally, the number of infringements attributed to GA pilots must be considered within the context of the number of GA pilots and aircraft, and the number of flights and hours flown by them. BBGA, on their website www.bbga.aero, state that there are over 8,000 GA aircraft in the UK, representing more than 90% of UK-registered civil aircraft. No statistics are available to show exactly how many GA flights are undertaken and how many hours are flown in any given year, but it is probably safe to say that that those flights resulting in an airspace infringement represent a small proportion of these. That does not suggest there is not a problem, as each infringement will carry with it some degree of flight safety risk. Infringements are caused by all sectors of the aviation community and every effort should be made to reduce the number of occurrences. Infringement Trends 1200 annual total 1000 number of reports 800 600 400 200 381 314 413 344 314 326 376 341 517 630 829 814 1086 888 912 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 year Data is based upon MOR information held by the CAA. MORs are submitted in accordance with the requirements of CAP 382 The Mandatory Occurrence Reporting Scheme.
The objective of the MOR Scheme is to contribute to the improvement of air safety by ensuring that relevant information on safety is reported, collected, stored, protected and disseminated. The sole objective of occurrence reporting is the prevention of accidents and incidents and not to attribute blame or liability. The graph above shows the total number of reported airspace infringements per calendar year from 1996 to 2011. The increases in 2005 and 2006 are believed to be attributable (at least in part) to stricter infringement reporting requirements within NATS En-Route Limited (London, Manchester ad Scottish Control Centres) rather than an increase in the actual numbers. Such requirements have been extended to NATS Services Ltd (those airports at which NATS provides ATC), within MOD and other non-nats/mod service providers. Of note is the 2009 peak number, and subsequent and significant fall in numbers in 2010. Although the number of reported infringements in 2011 did not maintain this decline, the increase is relatively small and indications are that 2012 will see a further reduction. As already mentioned, the number of reported infringements is seasonal in nature the better the weather (traditionally during the summer) the greater number of aircraft flying at any time. Therefore the possibility of an airspace infringement increases. The following graph shows the mean number of reported infringements per calendar month from January 1996 to December 2011. 80 mean monthly infringements 1996-2011 70 number of reports 60 50 40 30 20 10 22 26 39 47 64 69 75 62 57 44 27 18 0 January February March April May June July August September October November December month
A look at the rolling 12-month total (below) helps to illustrate the impact of more rigorous reporting requirements, the introduction of these within NATS coinciding with 2005 s summer traffic/infringement peak. Several things are of note. Firstly, there is the relative consistency in the number of Airproxes over any given 12 month period. Secondly, the impact of more rigorous reporting requirements amongst ATC providers has been cumulative since 2005. Thirdly, the 2009 peak is evident, as is the subsequent (and sustained reduction) throughout 2010. Finally, note the somewhat sharper reduction in 2010 of infringements after the Stansted TMZs have been factored out, and the return to a rolling total similar to that associated with 2008.
Of significant concern is the safety impact of infringements. Infringements represent a major collision risk, and each year a number of Airproxes and losses of separation arise from them. As can be seen in the preceding graph, the number of Airproxes arising from an infringement has remained consistently low, however some variation has occurred, as can be seen in the following graph. The percentage rates for each year shown above have been obtained by dividing the number of Airproxes resulting from an airspace infringement divided by the number of reported infringements. Fortunately, the majority of Airproxes resulting from an infringement have either resulted in a low Airprox risk, represented a technical loss of separation and/or resulted in a slight increase in ATC workload. Another 10% of reported infringements result in a loss of standard separation, while a further 25% or more result in disruption to traffic, resulting in delayed approaches and departures, consequently impacting upon the travelling public. Infringements associated with air displays can result in disruption to display sequences; on occasion can lead to individual displays being stopped, consequently impacting upon the paying public. Therefore, a significant proportion of all infringements directly impact upon the public.
As mentioned earlier, approximately three quarters of all reported infringements can be attributed to General Aviation pilots. Whilst there are inevitably annual variations in this number, the numbers attributable to all airspace user groups have remained remarkably consistent since at least 2000. In the following pie chart, GA = General Aviation, AOC = Aircraft Operators Certificate (commercial operators), Mil = Military and Unknown = not identifiable, could be any of the other categories. Infringements by airspace user group 2% 3% 15% 17% 60% GA (UK) GA (other) Mil AOC Unknown
Of the various kinds of airspace structures, those associated with airfields (Control Zone, Control Area, airway, Danger Area, ATZ, etc) terminal airspace are the most frequently infringed. Each year around 80%-85% of all reported infringements will occur in airspace established to protect aircraft at the critical stages of flight landing and taking off. As can be seen in the following graph, the majority of these occur in the South East of England, in or beneath the London TMA and affecting one of the busiest and complex airspaces in the world. Not only do they represent almost a half of all terminal infringements, in 2011 they also represented a third of all reported infringements in the UK FIRs. Some of the London area hot spots are shown in the map extract below. Each numbered circle represents an infringement red for those leading to an Airprox and orange for loss of separation; all others are shown in yellow. Note the number of infringements occurring in the vicinity of the Luton, Stansted and London City CTRs/CTAs, and also in the westerly portion of the London Control Zone. In each
case these will have seriously impacted upon airport operations and in the most severe of cases will curtail arrivals and departures, affecting dozens of aircraft in the air and on the ground, and thousands of passengers. The resultant delays and avoidable fuel burn will have significant operational, economic and environmental impacts. Whilst the map is now several years old and the distribution of infringements may have changed, the Luton, Stansted and London Control Zones remain infringement hotspots.
Prosecutions An airspace infringement may result in prosecution, however the CAA views this as an option of last resort. As can be seen from the supporting data, infringements leading to prosecutions represent a very small proportion of the overall number of reported occurrences. The number of prosecutions has progressively diminished, whilst the award of other measures such as Formal Conditional Cautions has increased. year (note 1) infringements (note 2) ARE investigations (note 3) ARE investigations as % of MOR infringements (note 4) Cautions and Conditional Cautions (note 5, note 6) Cautions and Conditional Cautions as % of MOR infringements Prosecutions (note 6, note 7) Prosecutions as % of MOR infringements total Cautions/ Prosecutions total all Cautions/ Prosecutions as % of MOR infringements 2000 (note 7) 344 9 2.62% 0 0.00% 5 1.45% 5 1.45% 2001 314 13 4.14% 0 0.00% 9 2.87% 9 2.87% 2002 326 44 13.50% 4 1.23% 17 5.21% 21 6.44% 2003 376 51 13.56% 15 3.99% 10 2.66% 25 6.65% 2004 341 45 13.20% 15 4.40% 8 2.35% 23 6.74% 2005 517 52 10.06% 22 4.26% 5 0.97% 27 5.22% 2006 630 40 6.35% 19 3.02% 5 0.79% 24 3.81% 2007 811 48 5.92% 14 1.73% 3 0.37% 17 2.10% 2008 814 32 3.93% 12 1.47% 7 0.86% 19 2.33% 2009 1086 45 4.14% 11 1.01% 4 0.37% 15 1.38% 2010 891 54 6.06% 22 2.47% 3 0.34% 25 2.81% 2011 912 32 3.51% 17 1.86% 8 0.88% 25 2.74% total 7362 465 6.32% 151 2.05% 84 1.14% 235 3.19% NOTES: 1. Calendar year. 2. Source: CAA MOR Database. 3. May include investigations into infringements not subject to MOR, eg on the basis of police report(s). 4. As % of infringements subject to MOR. 5. 'Conditional Cautions' may include recommendation for further training as an alternative to prosecution. 6. May include cautions/prosecutions arising from investigations conducting during previous calendar year. 7. May include cautions/prosecutions arising from investigations conducting during 1999.
The Airspace Infringement Working Group (AIWG) AIWG is a CAA-sponsored group established to monitor airspace infringement data and identify trends in order to instigate remedial action through regulatory or industry bodies in order to minimise the number of infringements and the risks associated with them. AIWG considers infringements of all types of airspace by all categories of pilot and whether airspace design or pilot awareness are features of the pattern of infringements. In addition, it has carried forward the findings and recommendations of the CAA s 'ON TRACK' project. Having considered statistical or other evidence, AIWG makes recommendations and takes action through its members to alleviate potential problem areas. These recommendations may be UK-wide, site-specific, or user-specific. AIWG sponsors the Flyontrack website, the purpose of which is foster awareness of the infringement issue and to encourage participation in resolving GA-related airspace infringements and to submit suggestions to AIWG for consideration and subsequent action. The following organisations are represented on AIWG: the CAA Directorate of Airspace Policy and the Safety Regulation Group (Flight Operations Inspectorate (General Aviation), Licensing and Training Standards Department; Aerodrome and Air Traffic Standards Department) and the Corporate Communications Department; NATS Ltd, Ministry of Defence, Airport Operators Association, AOPA, BGA, BMAA, GASCo, GATCO and invited representative(s) of GA community and other participants as required for specific issues. USEFUL WEBSITES: Further links can be found elsewhere on the Flyontrack and ASI websites. Numerous websites run by pilot associations carry articles on infringements and related issues. Numerous pilot web forums have discussion threads in which infringements are discussed there is a wealth of information and helpful advice out there to be accessed. www.nats-uk.ead-it.com/vfrcharts http://www.caa.co.uk/ga http://www.caa.co.uk/lasors http://www.caa.co.uk/pubsearch http://www.caa.co.uk/vfrguide www.flyontrack.co.uk www.ais.org.uk www.nats.co.uk/operational/pibs/index.shtml www.airspacesafety.com Aeronautical Charts (including VFR chart amendments) General Aviation (includes links to GA safety material, including GASIL (General Aviation Safety Information Leaflet) Safety Sense Leaflets and other safety awareness material) LASORS Publication Publications Search VFR Guide Flyontrack Aeronautical information Service Preflight Information Bulletins (PIBs) Airspace and Safety Initiative