What happened
On April 4, 2009, a Piper PA-34-220T (registration CS-DER) departed Évora Municipal Aerodrome for a flight training mission. The crew, consisting of an instructor and a student pilot, intended to perform an ILS approach to runway 26 at Montijo Air Base (Base Aérea nº 6).
During the approach, heavy military traffic in the area required Air Traffic Control to instruct the crew to fly directly to a position only 5NM from the runway threshold, authorizing an immediate ILS interception. This compressed the time available for the crew to configure the aircraft. As the student pilot intercepted the localizer and glide slope, the crew performed various configuration tasks, including adjusting flaps.
During the flare, the instructor noticed the aircraft was descending abnormally, suggesting the landing gear was not extended. The instructor attempted to initiate a go-around, but the aircraft' and the propellers struck the runway surface. The crew subsequently returned to Évora, where they confirmed the gear was down and the aircraft landed without further incident. The impact caused severe damage to the propeller tips of both engines.
The investigation
The GPIAAF investigation examined the aircraft's maintenance history, the crew's performance, and the operational environment. The investigation found that the landing gear system was fully functional and had no prior history of anomalies. However, the investigators noted that the instructor had previously pulled the circuit breaker for the gear warning horn to prevent a distracting audible alert during the approach, which prevented the crew from receiving an automated warning that the gear was not down.
Findings
- The primary cause of the incident was the propeller strike resulting from the landing gear not being extended at the time of touchdown.
- A significant contributing factor was the failure to follow three critical items in the Landing Checklist, which would have alerted the crew to the gear configuration.
- High workload contributed to the error, as the crew had to manage rapid configuration changes due to heavy military traffic and ATC instructions that shortened the approach.
- The instructor's decision to disable the gear warning horn via the circuit breaker removed a vital safety alert.
- The student pilot had very limited experience in this specific aircraft type, having only completed three flights in the model.