French investigators have detailed a serious airprox incident which occurred at Paris Charles de Gaulle when an Embraer 170, executing a go-around, drifted into the climb path of an Airbus A320 departing simultaneously from the parallel adjacent runway.

While descending to runway 26L on 21 October 2020 – during a period of strong crosswinds and turbulence – the Hop Embraer aborted its approach at 200ft, following a windshear warning.

Its crew applied a windshear manoeuvre, climbing to 1,500ft while maintaining a wings-level attitude, and then notifying the tower controller of the go-around.

But the strong crosswind had caused the Embraer to drift to the right in the meantime, straying into the vicinity of the Brussels Airlines A320 taking off from runway 26R.

French investigation authority BEA says the controller – about 10s after hearing of the go-around – attempted to resolve the conflict with emergency phraseology, instructing the Embraer crew to turn left onto a heading of 240°.

“The crew read back the instruction but the controller’s order to change the heading was not followed,” says the inquiry.

BEA says the Embraer crew was complying with a collision-avoidance procedure and stopped the turn on passing a heading of 250°. The crosswind meant the aircraft was still tracking 263°, towards the A320’s path.

E170 A320 airprox-c-BEA

Source: BEA

Flightpaths of the A320 and the Embraer 170 with point ‘7’ the moment of closest approach

Owing to a busy radio frequency, the Embraer crew had not told the controller about the collision-avoidance resolution.

The controller intervened to order the A320 crew to stop climbing – but did not use emergency phraseology. The A320 crew responded that they were following a collision-avoidance advisory.

BEA says the Embraer crew then “ambiguously” informed the controller of their own collision-avoidance advisory, using the past tense, which might have led the controller to believe the conflict was over – and meant the controller was giving orders to the crews even as the conflict resolution was continuing.

Analysis of the aircraft flightpaths shows they came within 0.09nm – about 550ft – horizontally and 460ft vertically at their point of closest approach.

F-HBXK Embraer 170 Hop-c-Bene Riobo Creative Commons

Source: Bene Riobo/Creative Commons

Phraseology issues complicated efforts to resolve the conflict, the inquiry found

BEA says the A320 crew stopped the climb at about 2,000ft as part of the resolution advisory, and the Embraer crew, after flying clear of the conflict, resumed a left turn onto a heading of 200°.

Investigators state that “insufficient consideration” was given to implementation of simultaneous runway operations during strong crosswinds and with the risk of windshear. The inquiry adds that the Embraer crew’s compliance with the windshear procedure up to 1,500ft altitude – irrespective of whether windshear was still present – could have delayed subsequent aircraft-separation actions.

None of the occupants – totalling 62 on the Embraer (F-HBXK) and 41 on the A320 (OO-SNE) – was injured.