History of Flight
The aircraft, a Cessna Citation 550 registered VP-CTJ, departed Lisbon Airport at 1750 hrs on 30 March 1999 for a flight to St Mawgan Airport, Cornwall, operated by a single pilot. The commander contacted St Mawgan ATC at about 200 nm and received weather information. The surface wind was 160°/10 kt and Runway 13 was in use. However, the commander requested an ILS approach to Runway 31, considering a coupled ILS approach with a tailwind preferable to a PAR approach to Runway 13.
The commander flew a coupled approach without incident. At 4 nm, he was cleared to land and advised of a 170°/12 kt wind, giving a 7 kt tailwind. He disconnected the autopilot when visual with the runway at an estimated 280 feet agl. He informed the Tower controller he was visual at about 200 feet and declined an offer to reduce runway lighting.
The visual segment appeared normal until, at about 140 feet agl, the commander was temporarily blinded by landing lights reflecting from light mist. He prepared to execute a missed approach but regained sight of the runway. However, a higher than normal rate of descent had developed, and the aircraft sank rapidly into the glare of the approach lights. The commander applied full power and pulled back on the control column, felt a light bump, and landed on the runway at 2000 hrs.
The aircraft struck and damaged the AR15 surveillance radar marker and the PAR reflector. On final approach, the aircraft was below the coverage of radar sites, so no recorded data were available. The PAR was set for Runway 13 and did not monitor the approach.
ATC Recording
An extract from the ATC tape described the event: the controller saw the aircraft's lights descending out of fog, then a very sharp rate of descent, with the landing light disappearing below the threshold lights. The controller thought the aircraft had gone into the field at about a quarter-mile final.
Meteorology
The initial weather (1850 hrs METAR) was: surface wind 160°/10 kt, visibility 3,500 metres in mist, cloud 4 oktas at 200 feet and 8 oktas at 400 feet, QNH 1010 mb/QFE 997 mb, temperature/dew point +10°C/+10°C. At approach start (1950 hrs), the METAR reported: surface wind 150°/10 kt, visibility 2,500 metres in drizzle, cloud 2 oktas at 100 feet, 6 oktas at 200 feet, and 7 oktas at 300 feet, QNH 1010 mb/QFE 996 mb, temperature/dew point +10°C/+10°C.
Damage and Markers
The AR15 marker, 8 feet high, is on the runway centreline, 10 metres inside the perimeter fence and 75 metres from the road. It is 266 metres from the start of paved surface and 566 metres from the glidepath origin. At that location, a normal approach would place an aircraft about 100 feet agl. Assuming a groundspeed of 120 kt and that the aircraft was on glideslope when the autopilot was disconnected at 280 feet, the rate of descent between that point and impact must have exceeded 950 fpm. The PAR reflector, 7 feet high, is 46 metres beyond the AR15 marker.
The first impact was on the forward underside of the left wing, just outboard of the main landing gear. Subsequently, one or both markers struck the left flap, which was of composite construction. Damage was confined to Zone 521 (forward of wing spar between Wing Station 79.00 and 145.75) and the left flap assembly. The left lower wing skin leading edge was dented, wing ribs buckled, and a stringer bowed. The left flap assembly was damaged beyond economic repair.
Subsequent Flight to Biggin Hill
The next morning, the commander inspected the damage and decided to ferry the aircraft to its maintenance base at Biggin Hill. He taped the damaged composite flap area and planned to fly with flap retracted. After refuelling both wing tanks, a slight fuel leak appeared from an underwing inspection panel; the left tank fuel gauge was unserviceable. The commander filled the right tank and fed both engines from it, estimating 1,500 lbs in the left tank and 2,400 lbs in the right tank. The aircraft departed St Mawgan at 0858 hrs.
During the flight, the commander, hand-flying, found a progressive tendency to fly left wing low, requiring increasing aileron input. In the visual circuit at Biggin Hill, he noticed significant fuel venting from the left wing. He informed ATC and landed flapless at 0957 hrs. After landing, the left wing tank was full (2,400 lbs) and the right held about 500 lbs.
Fuel System
The fuel system uses each wing as a tank feeding its respective engine. Crossfeed allows either engine to be supplied from the opposite tank. When crossfeed is selected from the right tank, the left engine receives fuel, and motive flow for the left tank's transfer pumps increases left tank fuel quantity. The manufacturer confirmed that during crossfeed, fuel transfers to the unused tank at about 950 lbs per hour.
The manufacturer stated the Master Minimum Equipment List allows one fuel quantity indicator inoperative provided both tanks are full, fuel used/remaining indicator and both fuel flow indicators are operative. The Flight Manual limits maximum fuel imbalance to 200 lbs, with an emergency limit of 600 lbs.
The left wing quantity indication had been intermittent prior to the accident; subsequent examination revealed a loss of contact on a wire in the left tank capacitance system, likely caused by the impact.
State of Registry Action
The aircraft was registered in the Cayman Islands. The Cayman Islands Civil Aviation Authority noted that no authority for single-pilot operation of VP-CTJ had been granted, though it would likely have been considered upon application with suitable training. They also stated that the accident invalidated the Certificate of Airworthiness and violated Articles 7, 9, and 11 of The Air Navigation (Overseas Territories) Order 1989 because the commander did not have the damage assessed by a qualified person or obtain a Ferry Permit. The Authority issued a caution rather than pursuing conviction, advising that single-pilot operations should not be conducted until formal application was made.