The Australian Carrier Alliance Aviation took action to stop the recurrence speed mode selection error by Embraer Crews after an incident in which E190 pilots did not notice that the jet was slowing when they first climbed the Solomon Islands.
Officers who flew jets from Honiara to Brisbane on February 23 last year did not monitor air speeds or detect any slowing speeds, the Australian Transportation Safety Agency said.
At about 134kt, when the captain noticed the lack of acceleration, they believed the drag was responsible and partially retracted the flap from setting 4 to setting 3 while it was below the minimum flap target speed.
This caused the aircraft to have reduced lift and airspeeds to 131kt.
The E190 has a stall protection system that includes a slow “amber zone” indication on air speed tape, with stick shaker activation as speed continues to drop to “red zone.”
It also warns the pilot with an amber pitch limit indicator on the primary flight display.
Investigators say the assistant officer noticed the pitch limiter and warned the captain before choosing to change the speed mode to “manual.”
As part of the pre-query procedure, the captain had to set the speed knob to “manual” mode. As a result, the target speed setting has been set to 80kt.
The captain then had to run another set of actions before running the “pre-start” checklist.
This series of actions included a selection of speed modes. The crew was intended to select “FMS mode” so that the flight management system could handle airspeed upon departure.
“It was not detected by either (the pilot), this step was omitted and the speed mode selection remained in the manual,” the inquiry says.
The choice of speed models did not have to be verbally stated by the captain or challenged the sect.
The crew formed the aircraft with a 4 flap setting for departure, with warm conditions and a 2,200m runway.
When the aircraft rotates, the target speed of 80kt was automatically changed to a V1 speed of 125kt. This target was displayed to the crew, but neither pilot noticed it.
While the aircraft was operating in “take-off” mode, it provided flight director guidance for the assistant officers for pitch attitudes, initially maintaining an airspeed of 144kt.
However, when the autopilot was involved at about 1,000 feet and the aircraft switched from a 1,200-foot “take-off” mode to “change vertical flight level”, the jet began pursuing a target airspeed of 125kt.
The aircraft began to turn left to follow the departure pattern, the assistant officer reduced thrust to climb the force, the captain checked weather conditions and monitored traffic conditions. Airspeed on the aircraft began to slow down, and the decline was initially not noticed to achieve its target.
Investigators say when the mates tried to increase airspeed manually and discovered that the jet was already in “manual” mode, they changed to the intended “FMS mode” based on their choice. This accelerated the aircraft to a correct target speed of 190kt.
None of the 70 residents were injured during the incident.
The carrier reviewed flight data after the outbreak, analysed 254 flights over 30 months between 2022 and 24, and found that 112 crews had not set relevant target speeds as manual speed settings were used during that time. The 76 crew members of these events changed their selection to “FMS mode” during takeoff. This risks distractions at critical stages.
Alliance Aviation has since changed its pre-flight procedures to reduce the possibility of such an incident, but Embraer also indicates that it will make changes to its operating manual.
