Airprox Report 2013086

2
Analysis and Investigation
CAA ATSI
The incident was reported to have occurred at approximately 1835, 19.5nm to the West of London
Heathrow at FL340. The A320 pilot was operating under IFR in receipt of a Radar Control Service
from London Control. CAA ATSI had access to area radar recording, together with the written
report from the A320 pilot and the NATS Ltd investigation report.
The estimated viewing aspect through the DV window is shown at Figure 1 below.
Figure 1: LH DV window Viewing Aspect
At the time of the reported occurrence (1835:22) the radar recording was filtered to show aircraft
operating within the level band FL320 and FL390 along with unknown primary contacts, these
have been circled red in Figure 2 below.
Figure 2: Swanwick MRT at 1835:22
An unknown primary contact was recorded in A320’s 10 o’clock at a range of 2.2nm. This
contact first appeared on the radar at 1828:53, in the vicinity of the village of Eling,
approximately 30nm West of Heathrow. The unknown contact routed West and landed at
White Waltham at 1846. This was identified as being a Tiger Moth aircraft which was
operating at low-level and was eliminated from the investigation.