Geneva Apron Airprox Involving Cessna C550 and Boeing 737-300 (PH-BTD)

Incident Overview and Aircraft Details On 8 April 2008 at 19:40 UTC, a serious airprox occurred on the traffic area (apron) of Geneva Airport (LSGG) at the intersection of taxiway OUTER and taxiway DELTA. The aircraft involved were a Cessna C550, registration HB-VNZ, operated by Jet Aviation Business Jet AG on a non-scheduled IFR commercial flight from Geneva to Zurich, and a Boeing 737-300, registration PH-BTD, operated by KLM Royal Dutch Airlines on a scheduled IFR commercial flight from Amsterdam to Geneva. ## Sequence of Events At 19:30:24 UTC, the Cessna C550 called Geneva APRON from the TAG Aviation apron at position Delta 4 and requested engine start. The crew consisted of two Swiss captains: a pilot flying in a supervised line flying (LIFUS) check and a type rating instructor supervising from the right seat. At 19:35:08 UTC, the crew requested taxi clearance and was cleared to the holding point for runway 23 via taxiway OUTER. The KLM 737-300 had landed on runway 23 from Amsterdam. At 19:39:43 UTC, after transferring from the aerodrome control frequency, the pilot reported having vacated runway 23 and was on taxiway DELTA. Geneva APRON cleared the 737 to taxi to stand 10 via taxiway LINK 4. At 19:40:00 UTC, the Cessna on taxiway OUTER approached the intersection with taxiway DELTA and passed just in front of the 737 at 19:40:10 UTC. The KLM pilot stated that he had to brake hard to avoid a collision and noted at 19:40:08 UTC that the Cessna had not been mentioned in the traffic information. The Cessna crew reported that they had not been instructed to give way to arriving traffic and were surprised to hear the KLM pilot report the hard braking. ## Contributing Factors and Investigation The apron controller stated that he had not been following the progress of the Cessna on the Swiss Airport Movement Area Control System (SAMAX) screen. Unfavorable weather conditions, including light drizzle, caused reflections from the apron lighting that affected night visibility for both the pilots and the apron controller. According to SAMAX traces, the Cessna covered 610 meters between taxiway ECHO and taxiway DELTA in 70 seconds, corresponding to an average speed of 17 knots. The KLM crew stated that the Cessna was taxiing very fast and that, without an emergency stop, a collision would have been inevitable. ## Meteorological Conditions The ATIS at the time reported variable winds at 2 knots, visibility of 6 km, light drizzle, few clouds at 100 feet and overcast at 600 feet, with a temperature of +2°C and a dew point of +1°C. The QNH was 1005 hPa. A METAR from MétéoSuisse at 19:50 UTC reported similar conditions with visibility of 5,000 meters and showers of rain.