What happened
On the night of 6 November 2017, an Embraer ERJ190-100LR, registration CS-TPV, operated by Portugalia, was taxiing at Nice Côte d’Azur airport for a scheduled flight to Lisbon. The flight was running over an hour late, which placed additional time pressure on the crew.
Following a non-standard push-back, the crew was instructed to taxi via taxiways T and A to holding point A1 for runway 04L. During the taxi, the crew performed engine start-up and various checklists. As the aircraft approached the intersection of taxiway A, the captain mistook a sign for taxiway A as the mandatory holding point sign for A1. Simultaneously, the aircraft was transitioning onto taxiway U, an old runway that is significantly wide.
The tower controller, aiming to maintain traffic flow and manage incoming arrivals, cleared the crew to line up and take off from runway 04L before the aircraft had actually reached the correct holding point. The crew, believing they were on the runway due to the green centerline lighting and the width of the taxiway, applied thrust. Approximately 20 seconds into the run, as the aircraft reached a speed of over 85 kt, the ground controller noticed the error on radar and alerted the tower. The crew immediately rejected the take-off, bringing the aircraft to a halt after traveling 922 meters.
The investigation
The BEA examined the flight data, cockpit voice recordings, and air traffic control communications. The investigation focused on the crew's situational awareness, the controllers' monitoring of the movement area, and the airport's infrastructure. Investigators analyzed the lighting differences between the taxiways and the runway, the lack of digital mapping tools (such as EFB or RAAS) on the aircraft, and the specific phraseology used during radio exchanges between the crew and the controllers.
Findings
Several contributing factors led to the unintended take-off run on a taxiway:
- Pilot Error and Confirmation Bias: The crew did not sufficiently monitor their position using charts or external visual references. The captain's misidentification of the taxiway sign, combined with the first officer's incorrect assumption that green lighting indicated a runway, created a confirmation bias that reinforced their erroneous belief they were on the correct path.
- Controller Oversight: The tower controller issued take-off clearance before the aircraft had passed the point where a route error was still possible. Additionally, the ground controller's attention was diverted by an unrelated request from another aircraft, leading to a failure to verify the aircraft's exact position.
- Communication Issues: The crew used non-standard phraseology, failing to use the word "negative" when stating they were already on the runway, which prevented the controller from immediately recognizing the discrepancy.
- Infrastructure and Equipment: The aircraft was not equipped with a Runway Awareness and Advisory System (RAAS) or an Electronic Flight Bag (EFIC) with digital maps. Furthermore, the width of taxiway U and its green centerline lighting were similar enough to the runway to mislead the crew at night.
Safety action
The aircraft operator updated its standard operating procedures to recommend leaving the stand on one engine for long taxi times and added a specific requirement to the before-take-off checklist to verify the runway. The aerodrome operator installed centerline lighting on taxiway A and updated safety publications to warn of the potential for confusion between taxiway U and runway 04L.