What happened
On 6 August 2004, a Cessna 210L, registration N249SP, was conducting a private flight from Paris Le Bourget Airport to Belfast City Airport. During the approach to Runway 22, the pilot utilized an ILS procedure under conditions of light winds and scattered clouds at 2,500 feet. While performing the approach, the pilot failed to deploy the landing gear or verify that the gear was in the down and locked position.
As the aircraft reached short finals, it was flying slightly below the 3-degree glideslope. Although the aerodrome controller observed that the undercarriage remained retracted and issued a warning to the aircraft, the pilot did not receive the transmission. The aircraft subsequently touched down with the gear up, resulting in no injuries to the two occupants but causing damage to the propeller and the lower fuselage.
The investigation
The investigation examined the aircraft's landing gear indication and warning systems. It was confirmed that the gear warning system was fully functional. The system utilizes a green light for a locked-down state and an amber light for the gear being fully up, triggered by microswitches on the landing gear legs. An audio warning horn is designed to activate if the gear is not locked when manifold pressure drops below a specific threshold.
Investigators noted that the audio warnings for both the gear and stall systems are routed through an overhead speaker rather than the pilot's headset. The pilot indicated that the gear warning horn's volume was relatively low and could be mistaken for the stall warning. Additionally, the investigation looked into the pilot's flight path, noting that a shallower approach required higher power settings, which likely delayed the activation of the gear warning until the moments immediately preceding touchdown.