What happened
On February 12, 2018, at 16:40 UTC, a Beechcraft 76 Duchess, registration CS-DCS, operated by Escola de Aviação Aerocondor S.A., experienced an abnormal runway contact at Ponte de Sor Airfield in Portugal. The aircraft was performing a flight operation when it made contact with the runway while the landing gear was not properly extended.
The investigation
The GPIAAF investigation examined the aircraft's landing gear system, maintenance records, and the crew's operational procedures. The investigation focused on the effectiveness of the landing gear warning horn and the consistency between the Pilot’s Operating Handbook (POH), Standard Operating Procedures (SOPs), and checklists. Investigators also reviewed the training department's methods for ensuring pilot compliance with gear extension checks and evaluated the role of modern noise-canceling headsets in potentially masking audible warnings.
Findings
- The primary cause of the event was the landing gear being in the retracted position during touchdown.
- The investigation noted that modern noise-canculating headsets used by crews can effectively cancel out the sound of the landing gear warning horn, preventing the pilot from hearing the alert.
- There was a lack of uniformity between the POH, SOPs, and checklists, which can complicate quick reference during critical flight phases.
- The incident was categorized alongside a trend of gear-up landings during instructional flights, often resulting from pilot distraction or interruptions to established flight routines.
Safety action
Following the investigation, several safety actions were established or are being developed:
- The landing gear warning horn test will now be included in every annual inspection.
- An operational placard will be placed on the instrument panel to remind pilots to verify the landing gear position.
- A visual warning (a "G" sign) may be added to the flight display when the aircraft reaches the appropriate speed for gear extension.
- The training department will implement the recording and playback of the warning horn sound during theoretical lessons to increase student awareness.
- Efforts are underway to explore piping the warning horn sound through the aircraft intercom to bypass the interference of noise-canceling headsets.
- Air Traffic Controllers (ATC) have adopted best practices to inform crews during the approach phase if they observe the gear is not down.
- Operators are encouraged to review methods for improving situational awareness and managing risks related to complacency.