Infringement occurrences

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Airspace Infringement of Class D Airspace - Birmingham Control Area 1

Airspace 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.

Focus on

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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