Air Canada E190 at Toronto on Mar 11th 2013, did not follow two instructions to go around

Last Update: July 22, 2024 / 13:44:06 GMT/Zulu time

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Incident Facts

Date of incident
Mar 11, 2013

Classification
Incident

Airline
Air Canada

Flight number
AC-178

Departure
Edmonton, Canada

Destination
Toronto, Canada

Aircraft Registration
C-FLWH

Aircraft Type
Embraer ERJ-190

ICAO Type Designator
E190

An Air Canada Embraer ERJ-190, registration C-FLWH performing flight AC-178 from Edmonton,AB to Toronto,ON (Canada), was on final approach to Toronto's runway 24R cleared to land when the tower controller instructed "178, go around" without response and repeated "178, go around", again without response. The aircraft continued for a safe landing on runway 24R, after landing tower inquired "Air Canada 178, did you hear my calls?" with the crew responding "We heard them but thought they were for somebody else", tower continued "Did you see anything on the threshold?" with the crew reporting "not a thing". The aircraft was subsequently instructed to vacate the runway and taxied to the apron.

NAV Canada reported that a Sunwing Boeing 737-800 parked at Gate H16 had needed maintenance, a mechanics had driven a van to the aircraft and had entered the aircraft. The vehicle started to move without a driver on board and rolled towards runway 24R when AC-178 was about 0.75nm out and crossed the runway coming to a stop on soft ground on the other side of the runway. A subsequent inspection found the vehicle with the engine running and gear engaged. Based on the ground radar target moving across the runway tower had instructed AC-178 twice to go-around however without reply, the landing was continued. When the mechanics later came out of the aircraft he found the van missing. The Sunwing 737 received damage by the unmanned moving vehicle.

The Canadian TSB reported that the vehicle departed gate H16 southeast bound without a driver on board heading towards the threshold of runway 24R, tower instructed AC-178 on short final to go around, the aircraft however continued, passed directly over the vehicle and landed safely. The vehicle was located shortly after southeast of taxiway D7. The TSB is currently assessing whether an investigation into the occurrence will be opened.

On Jul 22nd 2024 The Aviation Herald was able to retrieve the final report completed by Canada's TSB on May 21st 2014 however never released to their website. The report concludes the probable causes of the serious incident were:

- The vehicle was left unattended in drive gear, resulting in the vehicle rolling across the active arrival runway.

- The air traffic controllers were unable to determine the identity of the target on the ground radar and as a result were uncertain as to its intended path.

- The airport surface detection equipment at the tower controller’s position was not being monitored. When the Stage 1 runway monitoring and incursion alert system (RIMCAS) visual alert was activated, it went unnoticed.

- The first air traffic control go-around instruction was masked in the cockpit by a louder overlying enhanced ground proximity warning system automated callout, and the crew did not hear it.

- The second air traffic control go-around instruction issued by the tower controller was truncated by the transmitting and receiving radios. This, in combination with a rapid speech rate and elision, caused the aircraft call sign to be absent from the received transmission.

- Although the crew heard a “go-around” transmission, without other supporting cues such as visually sighting an obstacle, the crew did not interpret the instruction to apply to them. Consequently, the communication was insufficient to challenge the flight crew’s mental model of the situation, or their expectation of an uneventful landing.

- The RIMCAS Stage 2 aural alert was heard by the controllers 2 seconds before the conflict, which was too late to provide a useful warning.

- The vehicle beacon did not meet the standard required for airport
operations, decreasing the likelihood that it would be seen by ground personnel, the flight crew or air traffic control.

- The flight crew did not see the vehicle and passed directly overhead, separated by approximately 35 feet, resulting in a risk of collision.

Other findings

- The guidance provided to maintenance crews regarding the procedure to isolate the digital voice–data recorders was unclear and as a result, important data relevant to the investigation was lost.

The TSB analysed:

The investigation determined that all of the individuals involved in the occurrence were adequately experienced, trained and licensed, and were operating without the negative effects of fatigue. Therefore, the analysis will focus on the underlying reasons that the risk of collision occurred and how the defenses in place to prevent this type of occurrence failed.

After moving the vehicle forward several feet and getting out to assist the groomer, the technician did not intend to be out of the vehicle for very long, and did not secure it as required by the Greater Toronto Airports Authority. The fact that the transmission was left in drive would normally have been noticed by vehicle movement upon exiting but the vehicle did not initially move. The surrounding noise from the rain and the ground power unit may have masked the sound of the vehicle’s movement and striking of the aircraft cowling.

The vehicle was not noticed as it moved slowly across the apron. The ground controller first saw a very slow-moving unidentified airport surface detection equipment (ASDE) target shortly after its appearance on intersection DV but was unaware of the target’s identity or intentions. The controller planned to monitor the target, and returned to other tasks. When attention was returned to the target 2 minutes later, the target was on the runway. The 3 controllers attempted to determine the target’s identity but could not visually see the vehicle, possibly due in part to the inadequate vehicle beacon.

The ASDE in the tower was an older technology that did not have the functionality of current models. Newer ASDE’s have the ability to display identity tags on surface vehicles and aircraft, allowing the controllers to positively identify radar targets. If this information had been available to the controllers, they would have been able to identify the hazard sooner.

The runway monitoring and incursion alert system incorporated within the ASDE system did not provide alerts as intended. The tower controller’s display was set to monitor the runway as required, but this display was not being attended to at the time of the occurrence. The ground controller’s display, which was being attended to by both controllers, was not set to provide RIMCAS warnings.

The Stage 1 visual warning appeared on the tower controller’s display 23 seconds before the conflict, 7 seconds later than intended, reducing the time available for the tower controller to recognize the conflict and react. The Stage 2 visual and aural alert activated 2 seconds before the conflict, too late to provide a useful warning, and after both go-around instructions had been transmitted.

When the aircraft radios received the first go-around instruction, there was a simultaneous broadcast in the cockpit of an automated enhanced ground proximity warning system callout. The callout was louder than the received radio transmission and the transmission went unnoticed by the flight crew.
The audio delays encountered in the transmission and reception were both within the limits specified by the equipment design standard. These inherent delays are very minimal and unnoticeable in day-to-day operations because the delay normally occurs during the small amount of time between push-to-talk activation and the speaker beginning to talk.

The controller issued the second go-around instruction by pressing the push-to-talk switch and immediately talking at a rapid pace, responding to the urgency of the situation. The pronunciation of the call sign “Air Canada” was significantly elided. Due to the rapidity of speech, elision and inherent delays in the radio systems, the resultant audio, which arrived at the flight crews headsets, was devoid of the term “Air Canada”, or its elided counterpart ”ɛrkænə”.

On short final to land, the flight crew had a clear view of the entire runway and was aware that the previous landing traffic had cleared the surface. The weather was adequate, the approach was stable, and radio traffic on the frequency was light. The flight crew focused their attention on the detailed task ahead and was expecting a typical non-eventful landing.

What is expected is a key factor in attention behavior and, as a result, cues that indicate that the situation is not as expected may not attract attention from anticipated tasks. The implication is that situations will appear normal or familiar unless the “out of the ordinary” is of sufficient magnitude to attract attention and subsequent analysis.

Although the crew heard a “go-around” transmission, without other supporting cues such as visually sighting an obstacle, the crew did not interpret the instruction to apply to them. Consequently, the communication was insufficient to challenge the flight crew’s mental model of the situation, or their expectation of an uneventful landing.
Incident Facts

Date of incident
Mar 11, 2013

Classification
Incident

Airline
Air Canada

Flight number
AC-178

Departure
Edmonton, Canada

Destination
Toronto, Canada

Aircraft Registration
C-FLWH

Aircraft Type
Embraer ERJ-190

ICAO Type Designator
E190

This article is published under license from Avherald.com. © of text by Avherald.com.
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