Infringement occurrences

While we understand that many pilots are currently unable to fly due to COVID-19 restrictions we aim to continue to release safety education and awareness material to support the GA community with the future return to flying and continue to help promote longer-term safety awareness. To meet that aim we have launched a new series of narratives focusing on infringement occurrences.


Class A airspace: Cotswold Control Area

Infringement of Class A airspace – Cotswold Control Area

Date 20 August 2020
Aircraft Category Fixed-wing Microlight
Type of Flight Instructional Flight
Airspace/Class Cotswold CTA / Class A

Met information

At the time of the infringement the local QNH both at Brize Norton and Fairford was 1003 hPa. The cloud was BKN (5-7 oktas) at 4,800 feet and the forecast 5,000 feet wind on the UK Low-level Spot Wind Chart (Form 214) was 190/30.

The Air Traffic Controller

The Air Traffic Controller reported observing an unknown aircraft squawking 7000 indicating FL071 (7,100 feet based on 1013 hPa) enter the lateral confines of L9 in the vicinity of the IFR reporting point GAVGO, which is near Swindon. The aircraft remained in L9 for a period of 9 minutes 32 seconds. The aircraft was later observed to change to a Brize Norton conspicuity squawk (3737) but the Brize Norton Air Traffic Service Unit was unable to establish contact with the pilot.

The Pilot

The pilot reported that the training flight was being conducted in very local and familiar airspace. Navigation was being carried out using a 1:250K VFR chart with no GPS/Moving Map. The initial part of the flight was conducted under a layer of cloud (reported to be at 4000-5000 feet) but training was made difficult due to turbulence. The aircraft was turned south to remain clear of the Cotswold CTA with a base of FL065 and climbed above the cloud. Due to strong winds aloft, the aircraft was not positioned as far south an anticipated and with repeated turns the aircraft was ‘blown back’ into L9. The pilot found it difficult to determining their position due to only intermittent sight of the surface as a result of operating above cloud; they felt that the infringement was increased due to the low QNH.

Causal Factors/Findings

1:250,000 VFR charts have a vertical limit of airspace of 5000 feet ALT. The decision to climb to an altitude where no airspace information was available in the cockpit was the result of the instructor being  inadequately prepared for this flight. Figure 1 compares the information available on the 1,250,000 with the 1:500,000 chart. Figure 2 shows the warning annotated on all 1:250, 000 charts to remind users of the vertical limits.

1,250,000 vs 1:500,000 chart

Figure 1: 1,250,000 vs 1:500,000 chart

1:250, 000 chart warning to remind users of the vertical limits

Figure 2: 1:250, 000 chart warning to remind users of the vertical limits

The infringement lasted 9 minutes 32 seconds. Figure 3A shows the area on a 1:500,000 chart. Figure 3B shows the same area on the chart available to the instructor in the cockpit.

Area shown on a 1:500,000 chart

Figure 3A: Area shown on a 1:500,000 chart


Area on the chart available to the instructor

Figure 3B: Area on the chart available to the instructor

When it became clear that prevailing weather conditions required a change to the plan after departure the instructor should have either abandoned the flight or revised their plan. To mitigate against risks associated with over confidence/complacency their revised plan needed decisions based on aeronautical information available in flight, rather than perceived knowledge.

The instructor chose to operate without a Moving Map. The CAA and safety partners actively encourage all pilots to incorporate the use of Moving Maps in both pre-flight planning and in-flight.  When properly configured and used effectively, a visual and aural airspace warning would have been given alerting the pilot of their proximity to controlled airspace.

The instructor failed to recognise the Threats associated with cloud base and strong winds aloft. This resulted in the pilot losing situational awareness of the aircraft’s position. Once above cloud and unable to maintain positional awareness, the pilot made an Error in not requesting an air traffic service (ATS) from the local Lower Airspace Radar Service unit; Brize Norton is just 12NM from the location of the infringement.

At 1003 hPa, the QNH was not uncharacteristically low but it meant that the aircraft was some 300 feet higher on the local QNH when adjusted for the Standard Altimeter Setting (the correct pressure datum of the Cotswold CTA). However, the aircraft was still flown some 600 feet higher than the base of controlled airspace. Had the Instructor had the correct chart available and having stated they were aware of the Class A airspace with a base of FL065, they should have incorporated a maximum altitude of 6,000 feet on the QNH of 1003 hPa into their plan to remain below controlled airspace. This, in line with Take 2 guidance, would have ensured they were operating below the CTA and have a buffer of 200 feet to allow the management of the Threats associated with turbulence or student handling error.

When the pilot eventually displayed a Brize Norton SSR code the unit was unable to establish 2-way communications. In the first instance a pilot should only select the conspicuity code (3737) when instructed to do so or in accordance with local procedures.  Had the pilot intended to display the Frequency Monitoring Code (Listening squawk) the code selected should have been 3727 with the relevant frequency selected (124.275 MHz).

Instructors often lower the volume of the comms panel/radio during instructional flights as constant R/T can distract the student and impede in-cockpit talk between instructor and student.   It is not uncommon in occurrence involving instructional flights for ATC not to be able to establish communication with the pilot for this reason.

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Class D Airspace: Stansted Control Area 4 and Luton Control Area 1

Infringement of Class D airspace – Stansted Control Area 4 and Luton Control Area 1

Date 26 September 2020
Aircraft Category Fixed-wing Aeroplane
Type of Flight Recreational Flight
Airspace/Class Stansted & Luton CTA / Class D

The Air Traffic Controller

The Air Traffic Controller reported that they had traffic on a right-base for Runway 25 at London Luton Airport descending to 3,000 feet. A radar contact was seen to climb into controlled airspace south of Royston passing 2,600 feet before stopping the climb at 3,000 feet on an approximate track of 250o. Traffic information was passed to the Luton arrival aircraft and it was turned onto a shorter final to avoid the infringing aircraft. At this point the unknown aircraft selected 0013 squawk and the controller was able to ascertain their callsign and get 2-way communication with him. The pilot informed the controller they were leaving controlled airspace to the north which they subsequently did. The aircraft was then identified and given a service as per the pilot’s request. The Luton arrival was then re-vectored and completed a safe approach to land.

The Pilot

The pilot reported carrying out a recreational flight from Duxford to Cornwall via Wing (west southwest of Leighton Buzzard) to route to the north of the Luton Control Zone. The route was planned to be flown at 3,000 feet to remain below the CTAs with a lowest base of 3,500 feet. The plan was to climb straight ahead to 3,000 feet on a heading of 251o after departure from Runway 24 (Figure 1).

Figure 1

Figure 1

On the morning of the flight there was a strong northerly wind flow down the east side of the UK. The associated TAF were as follows:

  • Stansted: 300/14, PROB 40 TEMPO 2606/2609 32018G28
  • Luton: 300/14, TEMPO 2606/2706 33018G28.
  • The forecast 2,000 feet wind at 5230N 00E was 340/35 (35 knots at 90o to the planned track)

Just before departure an aircraft called Duxford Information to state they would be conducting visual circuits at Fowlmere (2.5NM west southwest of Duxford). On lining up for departure the pilot was informed of the traffic at Fowlmere and the surface wind “being something like 310/16”.

On climb out the pilot encountered the most vigorous turbulence that they could recall flying in for many years. They elected to hold runway heading as best they could to climb straight ahead out of the ATZ without turning right to the track of 251o degrees to enable them to remain clear of Fowlmere (blue line in Figure 2); the passenger was asked to look out for the Fowlmere circuit traffic. Given the turbulence, the pilot elected to climb at best rate of climb speed, which was approximately 80 knots, with the aim of getting into smoother air as soon as possible.

Once clear of Fowlmere, the pilot called Duxford to leave their frequency, changed to Luton Radar on 129.550 MHz and then selected the Luton Frequency Monitoring Code (FMC) of 0013. With the long nose of the aircraft, forward visibility is limited when climbing steeply; unfortunately, that meant fewer visual cues as to actual track were available to the pilot. As the aircraft approached 3,000 feet the pilot asked the passenger to pass them their Moving Map tablet that had been running since departure. The pilot was just noting they had had flown to the left of the airspace line (magenta line in Figure 2) when Luton Radar called to advise that they were indicating at 2,800 feet and was advised immediate descent to below 2,500 feet. Realising their error, the pilot responded that they were descending and turning north to head out of the Stansted CTA as quickly as possible.

Figure 2

Figure 2

ATC aspect

The airspace and track where the aircraft infringed is routinely used by Luton and Stansted traffic. This incident took place when the traffic was light and therefore the consequences of the infringement was minimal. Following agreement with the pilot of the arriving aircraft the controller re-positioned the aircraft and ensured minimum separation was achieved between the two aircraft However, in normal traffic levels with a continuous stream of arrivals the ability to reposition the aircraft without any impact on subsequent arrivals is unlikely. The workload increase for pilot and controller is significant under these circumstances with safety remaining paramount. One infringement of only a few minutes can result in many minutes of delay to operators, with additional fuel burn and emission also a consideration.

Causal Factors/Findings

The pilot carried out detailed and effective planning in route selection to remain outside controlled airspace and included the use of FMC along the route. In addition, they were equipped with a Moving Map which was intended to be used actively en-route. They also recognised the Threat associated with dual operations at Duxford/Fowlmere.

However, a minor change to the plan moments prior to departure allowed the introduction of lapses in wider Threat and Error Management. The decision to fly further south in strong cross winds and to climb at a higher rate resulted in the aircraft’s track being affected greater over a shorter distance the aircraft drifting further south of track than had been anticipated. The pilot, unaware of their ground track due to reduced forward visibility associated with the aircraft’s attitude then lost situational awareness and extended beyond that required to avoid the traffic flying circuits to the north of Fowlmere. By the time the aircraft was south abeam the Runway 25 threshold at Fowlmere, it was 1.2NM south and passing 1,500 feet. In addition, had the pilot identified that routing to the south of Fowlmere would take them closer to the Class D CTAs they may have identified the increased value to using the Moving Map. This would have enabled them to regain situational awareness lost through the aircraft’s attitude. The pilot could have either turned right back onto track or stop their climb below 2,500 feet to remain below the CTA. However, the pilot was faced with several distracting factors from their original plan and their capacity was rapidly being used in handling the aircraft in extremely turbulent conditions whilst considering the traffic at Fowlmere and the wellbeing of their passenger.

In their wider plan, the pilot had considered the Take 2 aspect to remain clear of controlled airspace but that was not revised following the amended plan to deviate to the south of Fowlmere and thereby fly close to the CTA. Had the pilot only climbed to, for example 2,300 feet, until closer to Royston, the infringement could also have been avoided. This probably did not enter the pilots thought process as the focus was on climbing out of the turbulence, avoiding the Fowlmere visual circuit, and selecting the next radio frequency and FMC.

Notwithstanding the lapses in Threat and Error Management, the pilot’s initial plan was good and incorporated several key measures to prevent airspace Infringements:

  1. Comprehensive planning including airspace avoidance and meteorology;
  2. Use of a Moving Map; and
  3. Use of an FMC.

That decision to use an FMC enabled early intervention by air traffic control to assist the pilot and resolve the situation promptly. In addition, detailed post-occurrence analysis and open and detailed reporting by the pilot enabled lessons to be identified to avoid a recurrence.

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Class D Airspace: Birmingham Control Area 1

Infringement of Class D airspace – Birmingham Control Area 1

Date 24 August 2020
Aircraft Category Fixed-wing Aeroplane
Type of Flight Recreational Flight
Airspace/Class Birmingham CTA-1 / Class D

The Air Traffic Controller

The Air Traffic Controller reported that Runway 33 was in use at Birmingham with one aircraft shortly to depart. The controller was alerted to an unknown aircraft entering CTA-1 indicating 1,900 feet and squawking 0010 (the Birmingham Frequency Monitoring Code). Using MODE S derived information, the controller made a transmission to the pilot and asked them to descend immediately. The departing aircraft was instructed to depart straight ahead to maintain separation to the west of the infringing aircraft. The pilot stated they were mistakenly inside the CTA and descended; the aircraft was identified, issued with a discrete squawk and, once clear of the CTA, offered a Basic Service. Sometime later the aircraft climbed again into the CTA to 1,600 feet and, when informed of the climb, the pilot carried out an immediate descent.

The Pilot

The pilot was prompt to submit a comprehensive report to the CAA. They reported that the aircraft had recently had a complete avionics refit with all original radios and navigation equipment replaced with fully integrated GPS/NAV/COM/MFD equipment, Electronic Flight Instruments and an autopilot. Initial flights post-installation were carried out for the pilot to become familiar with the basic instrumentation; the subject flight was planned for a longer distance to test the autopilot. The pilot openly admitted that the new avionics were not the reason for the infringement but “sloppy planning” carried out on the morning of the flight was a contributory factor. In that planning session, the pilot had ‘rubber banded’ the magenta line on the Moving Map. The red line in Figure 1 shows the route planned and that flown. Having taken the northern route around Birmingham many times, after departure the pilot usually routed at 1,900 feet to Lichfield Disused, then west between Cosford and Wolverhampton Aerodrome Traffic Zones taking them below the Birmingham CTA-3 with a base of 3,500 feet (blue line in Figure 1).

On the day of the infringement, the pilot followed their plan that took them west through, and not below, the similarly shaped but lower CTA-1 which has a base of 1,500 feet. On hearing their callsign broadcast by the Birmingham air traffic controller, the pilot’s first instinct was to disengage the autopilot and follow the requests of the controller. They then accepted a basic service and a discrete squawk. The second climb was thought to have occurred as the pilot wouldn’t normally fly as low as 1,500 feet over the built up areas to the west of Aldridge towards Walsall; they reported that they were most likely conscious of a lack of clearance with the terrain which, in that area, lies between 450 feet and 500 feet amsl. The rest of this flight, and the return flight home was uneventful.

The pilot added that on any other day they were sure they would have noticed the mistake of their plan in the air because the route was clearly wrong. However, distraction caused by focussing on the new avionics drawing more of their attention led them to miss the planning error.

After the occurrence, the pilot elected to take time with an instructor who was familiar with the new avionics to carry out some more familiarisation training and navigation practise.

Airspace Infringement of Class D Airspace - Birmingham Control Area 1 : Figure 1

Figure 1

Causal Factors/Findings

The pilot is to be commended by their openness and post-occurrence actions. This occurrence demonstrated the benefit of using a Frequency Monitoring Code (FMC); the pilot reported that they use them whenever they are available in the areas in which they are flying. This positive approach to, and correct use of, the FMC allowed the initial infringement to be resolved promptly by the controller and pilot. In addition, the pilot correctly operated their transponder with MODE C (ALT) alerting the controller to the infringement; had MODE C not been operated, the controller would have been correct to have ‘deemed’ the aircraft to be below the CTA. Had that been the case, the risk of a mid-air collision or the infringing aircraft being affected by wake turbulence would have been heightened.

Poor planning and a failure to double check the route and associate altitudes of the airspace resulted in confirmation bias that they were able to fly at 1,900 feet. In the planning phase, by creating a back-up on a paper chart, you are often notice additional information/details that you don’t always notice on your Moving Map display.

Even though the pilot was flying with a Moving Map, it is not known why there was no response to the alert. It is possible that the confirmation bias led the pilot to dismiss the alert without noting its subject. When properly configured and used, an airspace warning would have been given the pilot a timely alert of their proximity to controlled airspace.

In summary, the pilot did not carry out sufficiently detailed pre-flight planning which, combined with confirmation bias and distraction from overly focussing on new avionics, resulted in their flying into Class D controlled airspace without an air traffic control clearance. However, textbook use of an FMC allowed the infringement to be resolved in a prompt manner.

Despite some errors associated with Human Factors, the pilot has embraced a Just Culture and identified the benefits associated with completing the appropriate refresher training which was carried out with a Flight Instructor.

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Controller’s stories

A series of controller’s stories from NATS

Mark Davenport, an air traffic controller at Swanwick centre, talks about his experience with airspace infringements. Airspace Infringement Series: A controller’s story… (20 May 2019)

Brian Ringrose is an air traffic controller at Swanwick centre. He talks about his experience looking after airspace around Gatwick. Airspace infringement series: A controller’s story (12 April 2019)

Amanda Rhodes is an air traffic controller at Swanwick Centre.  She talks about her experience looking after airspace around Luton Airport. Airspace Infringement Series: A controller’s story (22 March 2019)


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