Hop! E170 at Paris on Oct 21st 2020, on go around veered into departure path of other aircraft

Last Update: May 31, 2023 / 17:23:51 GMT/Zulu time

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Photo of Hop! F-HBXK, Embraer ERJ-170 — Hop! F-HBXK, Embraer ERJ-170 (Photo credit: airlines470 / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Oct 21, 2020

Classification
Incident

Airline
Hop!

Flight number
AF-7739

Departure
Brest, France

Destination
Paris Charles de Gaulle, France

Aircraft Registration
F-HBXK

Aircraft Type
Embraer ERJ-170

ICAO Type Designator
E170

Airport
Charles de Gaulle International Airport, Paris

Airport ICAO Code
LFPG

A Hop! Embraer ERJ-170 on behalf of Air France, registration F-HBXK performing flight AF-7739 from Brest to Paris Charles de Gaulle (France), was on final approach to Charles de Gaulle's runway 26L descending through about 1000 feet MSL when the aircraft encountered windshear prompting the crew to initiate a windshear escape and go around maneouver. The aircraft turned to the right and came into conflict with an A320 which departed runway 26R at the same time. ATC stopped the A320's climb at about 2300 feet MSL and turned the aircraft to the north (to their right) immediately, the Embraer was turned immediately south (to their left) and resolved the conflict that way. The A320 continued to their destination, the Embraer positioned for another approach to runway 26L and landed safely about 15 minutes after the go around.

A Brussels Airlines Airbus A320-200, registration OO-SNE performing flight SN-3634 from Paris Charles de Gaulle (France) to Brussels (Belgium), departed runway 26R, stopped the climb at 2300 feet and was turned north before the aircraft continued the climb.

On Oct 30th 2020 the French BEA reported they rated the occurrence a serious incident involving the risk of a collision in mid flight and opened an investigation (no minimum separation was reported so far by the BEA). The BEA stated with respect to the E170: "Following a windshear warning, they interrupted the approach. The aircraft's path deviated to the right causing an abnormal approximation with another aircraft taking off on runway 26R."

According to Mode-S Data transmitted by both aircraft the Embraer did not transmit position data, based on time differences of arrival of their transponder transmissions at at least 3 receivers (MLAT) a position estimate with a possible deviation of several hundred meters suggests the aircraft was well established and on center line on the final approach to runway 26L descending through 1100 feet MSL descending at about 700 fpm and 134 knots over ground. A minute later the aircraft is shown to the right of runway 26R however, having crossed the extended center line of runway 26R a first time before the runway threshold, turning parallel to the runways, overflying the terminals at about 1900 feet MSL still at 134 knots over ground before initiating a steep climb trading speed for altitude (speed over ground decreased by 21 knots from 134 knots to 113 knots over ground) and turning to the left to the south crossing the departure path of runway 26R at about 3600 feet MSL almost exactly overflying the A320 at 2300 feet.

The transponder of the A320 transmitted position data showing the aircraft was exactly over the extended center line of runway 26R when they stopped the climb at 2300 feet and turned north, just as the Embraer, based on the positions estimated by MLAT crossed the extended center line of runway 26R a second time, this time at 3600 feet MSL almost on top of the A320.

On May 31st 2023 the French BEA released their final report concluding the probable causes of the serious incident, minimum separation 460 feet vertical and 0.09nm horizontal, were:

The following factors may have contributed to the abnormal proximity between the two aeroplanes and to the issuance of the TCAS resolution advisories:

- Insufficient consideration given, in the implementation of procedures associated with specialised simultaneous operations, to the combination of risks associated with a strong crosswind and the crew’s compliance with a Windshear procedure.

- Compliance with the Windshear procedure up to an altitude of 1,500 ft, irrespective of the effective presence of windshear conditions, which may have delayed the subsequent separation actions by the parties involved.

The BEA described the scenario:

The landing and take-off operations at Paris-Charles de Gaulle airport were taking place on the south parallel runways, in particular weather conditions, with a strong crosswind and moderate to severe turbulence below 1,500 ft.

The ERJ170 was at 500 ft on short final on runway 26L when the crew of the A320 were cleared to take-off from runway 26R.

At a height of 200 ft, a Windshear warning was triggered on board the ERJ170. The crew applied the procedure associated with this warning by interrupting the approach and keeping the wings level.

After eight seconds, when the ERJ170 flew through 580 ft in climb, the Windshear warning stopped. The crew identified the end of the windshear situation when the aeroplane flew through 1,000 ft, 11 s after the end of the warning. The crew continued complying with the procedure by keeping the wings level for a further eight seconds up to an altitude of 1,500 ft, in accordance with the operator’s operational instructions for the ERJ170. They then notified the controller of the windshear and the go-around.

Due to compliance with the Windshear procedure and the strong crosswind, the ERJ170 deviated northwards and closed in on the A320 taking off from runway 26R.

The controller attempted to resolve the conflict by using the emergency phraseology to order the ERJ170 to turn onto a heading of 240°, around 10 s after the ERJ170 had reported the go-around. The crew read back the instruction but the controller’s order to change the heading was not followed. In fact, complying with the TCAS procedure, the crew stopped the turn as they passed through a heading of 250° which resulted in a track of 263°. The crew of the ERJ170 did not immediately inform the controller of the TCAS resolution advisory due to the frequency being busy.

The controller then asked the crew of the A320 to stop climbing without using the emergency phraseology. The latter replied that they were following a resolution advisory emitted by their TCAS.

The crew of the ERJ170 then ambiguously informed the controller that they had also had a TCAS resolution advisory.

The crews followed the orders of the resolution advisory provided by their respective TCAS systems. The minimum separation reached during the incident was 0.09 NM and 460 ft.

Neither of the crews informed the controller of the end of their respective TCAS resolution advisories using the standard message set out in the phraseology rules. The use of the past tense in the non-standard message made by the crew of the ERJ170 stating that they had also had a TCAS may have led the controller to believe that the resolution advisory had ended. The controller therefore issued orders to the crews despite the ongoing resolution advisories.

Metars:
LFPG 211200Z 20021G32KT 9999 BKN032 BKN040 20/13 Q1002 NOSIG=
LFPG 211130Z 20026G38KT 9999 BKN032 BKN038 20/13 Q1002 NOSIG=
LFPG 211100Z 19024KT 9999 BKN033 BKN040 19/13 Q1002 NOSIG=
LFPG 211030Z 19022G33KT 9999 SCT033 BKN040 20/13 Q1001 NOSIG=
LFPG 211000Z 20022KT 9999 FEW033 BKN040 19/12 Q1001 NOSIG=
COR LFPG 210930Z 21024G34KT 9999 FEW033TCU BKN040 19/12 Q1001 NOSIG=
COR LFPG 210900Z 19025KT 9999 BKN048 20/11 Q1000 NOSIG=
LFPG 210830Z 18022KT CAVOK 18/11 Q1000 BECMG 19020G35KT=
LFPG 210800Z 16018KT CAVOK 17/11 Q0999 BECMG 19015G25KT=