History of the Flight
On 26 April 2012 at 1750 UTC, a serious incident occurred near London City Airport involving a Piaggio P.180 Avanti II (registration PH-DLN) and an Avro 146-RJ85 (registration EI-RJW). Both aircraft were conducting commercial passenger flights. Runway 27 was in use, with a strong south-westerly wind, good visibility, and scattered cloud at about 3,000 ft. PH-DLN had just taken off and turned right in accordance with its clearance, but subsequently flew into conflict with EI-RJW, which was on final approach from Dublin. Both aircraft were under a Radar Control Service.
The crew of PH-DLN reported climbing to 3,000 ft on the Thames Radar frequency about half a minute before the crew of EI-RJW reported established on the Runway 27 localiser. EI-RJW was instructed to establish on the glideslope and transferred to the Tower controller. PH-DLN appeared to establish on an easterly track at 3,000 ft before the controller noticed it had turned onto a south-easterly track, towards the final approach path.
The controller instructed the crew of PH-DLN to turn left onto 030°, but the instruction was apparently not complied with. A further instruction was given using the phrase "AVOIDING ACTION" with details of the conflicting traffic. At that point, EI-RJW was 3 miles ahead, descending through 2,800 ft. As PH-DLN began a left turn, the controller instructed it to climb to 4,000 ft. The minimum separation recorded on radar was 2.7 nm lateral and 700 ft vertical. No TCAS warnings were received by either crew.
Heading Indications
While at the holding point, the crew of PH-DLN had selected Directional Gyro (DG) mode for heading indications on their Horizontal Situation Indicator (HSI) and adjusted the indicated heading to match the runway QDM. After takeoff, slaved mode was selected. The crew were occupied with flying in turbulent conditions and did not recognise that a navigational error had occurred. After complying with the avoiding action, the crew realised the indicated heading was in error by about 60°. The crew reported that their heading reference system should normally be kept in slaved mode, with DG mode only used in case of failure. The pilot's report identified an operational error and the distraction posed by turbulence as causal factors.
Previous Occurrences
Similar navigation problems after departure from London City Airport had been reported previously. In October 2006, a Hawker 800XP experienced significant navigation problems. An AAIB Field Investigation (reference EW/C2006/10/10) revealed several similar incidents. Local magnetic anomalies in the area of the holding point could adversely affect cockpit heading indications and, in some cases, lead to heading system failure indications. Six Safety Recommendations were made concerning airport standards for magnetic anomalies, published aeronautical information, and advice to operators.