Sky Regional E175 at Toronto on Jan 28th 2019, rejected takeoff due to runway incursion by snow ploughs

Last Update: May 13, 2020 / 15:18:06 GMT/Zulu time

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Photo of Sky Regional Airlines C-FEJB, Embraer ERJ-175 — Sky Regional Airlines C-FEJB, Embraer ERJ-175 (Photo credit: "Fast" Eddie Maloney / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Jan 28, 2019

Classification
Incident

Cause
Rejected takeoff

Airline
Sky Regional Airlines

Flight number
RS-7665

Departure
Toronto, Canada

Destination
Dallas Ft. Worth, United States

Aircraft Registration
C-FEJB

Aircraft Type
Embraer ERJ-175

ICAO Type Designator
E175

A Sky Regional Airlines Embraer ERJ-175, registration C-FEJB performing flight RS-7665 from Toronto,ON (Canada) to Dallas Ft. Worth,TX (USA), was accelerating for takeoff from Toronto's runway 06L when tower instructed the crew to reject takeoff. The crew complied, rejected takeoff and brought the aircraft to a stop just short of the intersection of runway 06L and taxiway C2.

The Canadian TSB reported a convoy of snow ploughs and sweepers had been operating north of runway 06L and proceeded southbound on taxiway E. Ground control instructed the convoy to turn left onto taxiway C (parallel to runway 06L), the vehicles turned left, however onto taxiway C2 (high speed turn off from runway 24R) and were moving towards runway 06L crossing the hold short line. Ground control instructed the vehicles to stop, the vehicles stopped just short of the runway edge. Tower at the same time instructed the Embraer to abort takeoff.

On May 13th 2020 the Canadian TSB released their final report concluding the probable causes of the serious incident were:

Findings as to causes and contributing factors

These are conditions, acts or safety deficiencies that were found to have caused or contributed to this occurrence.

- The transponder installed on PLOW 862 was not updated to remove the code from the vehicle on which it had previously been installed. As a result, the incorrect code was shown on the ground controller’s display.

- NAV CANADA did not have procedures in place to track or report vehicle transponder errors to the Greater Toronto Airports Authority.

- Due to the reduced visibility from blowing snow, the operator of PLOW 862 was not aware that the vehicle was on Taxiway C2 as it approached the holding position. As a result, the operator was not looking for, nor expecting to see, any of the visual cues that would have alerted him that the vehicle was approaching an active runway.

- Because some of the visual cues at the holding position were obscured by snow, and others may not have been working, the cues were not conspicuous enough to alert the operator of PLOW 862 to the vehicle’s proximity to the runway. As a result, PLOW 862 and the following 2 vehicles incurred on the protected area of the runway.

- The ground controller recognized the incursion by PLOW 862 and instructed the vehicle to stop 4 times; however, the first 2 instructions were addressed to PLOW 170 rather than PLOW 862. Immediately after the ground controller used the correct call sign, PLOW 862 came to a stop 10 seconds and 270 feet after crossing the holding position on Taxiway C2.

Findings as to risk

These are conditions, unsafe acts or safety deficiencies that were found not to be a factor in this occurrence but could have adverse consequences in future occurrences.

- If air traffic controllers use abbreviated phraseology when issuing safety-critical instructions, there is a risk that the instruction will not be recognized or followed by flight crews.

Other findings

These items could enhance safety, resolve an issue of controversy, or provide a data point for future safety studies.

- The vehicle operators did not have access to any real-time navigation displays to assist with navigating the various taxiways and runways, such as moving maps or a global positioning system.

The TSB analysed:

All 4 of the vehicle operators were experienced in operating vehicles on the airport manoeuvring areas, and there was no misunderstanding of the air traffic control (ATC) instruction, where the vehicles were authorized to work, and the intended route.

The vehicle operators did not have access to any real-time navigation displays to assist with navigating the various taxiways and runways, such as moving maps or a GPS (global positioning system). The operators were knowledgeable about the area but were driving in conditions of reduced visibility.

The operator of the lead vehicle, PLOW 862, was instructed to proceed east on Taxiway C. However, after making a wide left turn to position snow near the south edge of the taxiway, he inadvertently turned onto Taxiway C2. Believing he was on Taxiway C, he continued onto Taxiway C2, and due to the limited visibility the other vehicles followed.

Due to the reduced visibility from blowing snow, the operator of PLOW 862 was not aware that the vehicle was on Taxiway C2 as it approached the holding position. As a result, the operator was not looking for, nor expecting to see, any of the visual cues that would have alerted him that the vehicle was approaching an active runway.

In addition to the reduced visibility, Taxiway C2 was covered in snow, which obscured the paint markings and the inset stop-bar lights. When investigators later examined the location, it was noticed that 1 light in each pair of elevated stop-bar lights was not working. Although it could not be determined if these lights were operating on the day of the occurrence, the reduced lighting likely would have further reduced the conspicuity of the holding position.

Because some of the visual cues at the holding position were obscured by snow, and others may not have been working, the cues were not conspicuous enough to alert the operator of PLOW 862 to the vehicle’s proximity to the runway. As a result, PLOW 862 and the following 2 vehicles incurred on the protected area of the runway.

The Greater Toronto Airports Authority (GTAA) conducted a risk analysis in 2012 regarding vehicle transponders and identified vehicle mismatch as a hazard. As a result, standard operating procedures (SOPs) were developed to prevent the situation from occurring in future. The SOPs in effect for installing and testing the transponders include programming a code for the new transponder and then using web-based software to check that the code is correct before the vehicle is operated on the manoeuvring area. Once the transponder and vehicle are operational, the vehicle operators have no method of checking the software themselves to verify that the transponder is displaying the correct code.

Normally the GTAA installs new transponder units in new vehicles that are to be operated on the manoeuvring areas of the airport. However, in this case there were no new transponders available, and so a used transponder was installed. Transferring of transponders between vehicles is not common; the majority of the installations are new units, and therefore would not have a transponder code pre-programmed in the unit. The used transponder was checked for proper operation and deemed to be serviceable before it was installed on PLOW 862, although it was programmed with the code PLOW 170.

The transponder installed on PLOW 862 was not updated to remove the code from the vehicle on which it had previously been installed (i.e., PLOW 170). As a result, the incorrect code was shown on the ground controller’s display.

Before the introduction of the advanced surface movement guidance and control system (A-SMGCS), the ground radar system at Toronto/Lester B. Pearson International Airport (CYYZ) was based on primary surveillance radar. At that time, vehicles did not have transponder codes, so controllers were used to seeing the targets without these codes appearing as tags on their displays. Over time, some targets began to have tags associated with them, but controllers were still using the extended computer display system (EXCDS) screen to get call sign information. Consequently, when there was a mismatch between the tag on the A-SMGCS display and the vehicle call sign, although controllers initially reported these errors to vehicle operators, they did not deem it a serious ongoing hazard.

At the time of the occurrence, the NAV CANADA control tower at CYYZ did not have procedures to follow if there was a mismatch between a vehicle call sign and its transponder code. It was reported that when the transponder program began, ATC would often challenge a vehicle that had a wrong or missing code; however, this could not be verified. In addition, there were no records available regarding the frequency or number of transponder code and vehicle call sign mismatches. Over time as fewer challenges were received, the GTAA assumed that fewer mismatches were occurring. Even though PLOW 862 had an incorrect transponder code for 7 weeks, the error was not identified or reported to the GTAA.

NAV CANADA did not have procedures in place to track or report vehicle transponder errors to the GTAA.

When the ground controller observed the vehicles crossing the holding position at Taxiway C2 on the A-SMGCS display screen, he used the call sign associated with the target (PLOW 170) when instructing the plow operator to stop. When the ground controller did not receive a response, he referred to the EXCDS screen and obtained the correct call sign (PLOW 862).

The ground controller recognized the incursion by PLOW 862 and instructed the vehicle to stop 4 times; however, the first 2 instructions were addressed to PLOW 170 rather than PLOW 862. Immediately after the ground controller used the correct call sign, but 10 seconds and 270 feet after crossing the holding position on Taxiway C2, PLOW 862 came to a stop.