What happened
On 1 February 2000, at approximately 14:19 UTC, a runway incursion occurred at Geneva Airport involving a commercial airliner and a light aircraft. A Boeing 737-400, operating as KLM 1931 from Amsterdam, was on final approach for runway 23. Simultaneously, a Piper PA28A, registration HB-OQS, was holding at the Yankee intersection.
After a Boeing 757 (Speedbird 728) vacated the runway via the Charlie taxiway, the air traffic controller instructed the HB-OQS to line up on runway 23 behind the incoming KLM flight. However, the pilot of the HB-OQS immediately aligned the aircraft on the runway. The controller did not notice this movement. The Boeing 737-400 subsequently landed on runway 23 and passed the aligned light aircraft at the Charlie intersection. The crew of KLM 1931 alerted the controller that the runway was occupied and intended to file an incident report.
The investigation
The investigation established that the HB-OQS pilot had moved onto the runway following the instruction to line up behind the incoming traffic. The investigation examined the radio communications, noting that 11 different radio contacts occurred between the tower and various aircraft during the critical period, which likely distracted the controller.
Analysis of the instructions revealed that the controller used the phrase "behind the incoming traffic" (in French, "derrière le trafic à l'arrivée"). The investigation found that this phraseology was not sufficiently precise to clearly distinguish between the aircraft currently vacating the runway and the aircraft on final approach. The pilot of the HB-OQS believed they were following instructions correctly, while the controller was unaware of the intrusion until the light aircraft signaled it was ready for departure.
Findings
- The primary cause of the incident was the premature alignment of the HB-OQS on the active runway.
- The pilot of the HB-OQS misinterpreted the controller's instruction regarding the sequence of traffic.
- The air traffic controller failed to notice the light aircraft entering the runway due to high frequency of radio communications and a lack of visual monitoring.
- The use of standard but imprecise phraseology contributed to the misunderstanding of the landing sequence.
Safety action
- Controllers and pilots should be reminded to use highly precise phraseology, especially when issuing conditional instructions.
- Increased vigilance is required during the read-back and hear-back process to prevent misunderstandings.
- Controllers must perform a visual check of the runway before authorizing take-offs or landings.
- Private pilots using the main runway should perform their own visual checks of the approach axis before lining up, regardless of ATC authorization.