Summary
On 20 July 2011, at 08:53 UTC, the AVRO 146-RJ100 aircraft, registration HB-IXP, took off under flight number LX 5187 and radio call sign "Swiss five one eight seven" on a ferry flight from Nuremberg to Zurich.
Shortly after take-off, at a height of approximately 400 ft above the ground, when the aircraft was still under manual control, the autothrottle (AT) and the flight director (FD)1 failed simultaneously. These could subsequently be regained, together with the autopilot (AP).
After an otherwise uneventful flight, the crew assumed that all systems were available with- out any restrictions. LX 5187 then received clearance for an approach on runway 14. When lined up on the localiser and at an altitude of 4000 ft AMSL, at 09:51:40 UTC the autopilot, the autothrottle and the flight director failed. A few seconds later the acoustic alert "bank angle" for a high bank angle sounded.
At 09:52:04 UTC, the red ATT (attitude) and HDG (heading) warnings appeared on the commander's electronic flight instrument system (EFIS) and the navigation data disappeared. On the copilot's EFIS displays the indications remained stable and allowed the aircraft to be controlled manually.
The copilot no longer trusted his indications; the commander took over control of the aircraft using standby instruments and also continued to conduct radio communications. Shortly afterwards, he reported to air traffic control that there were navigation problems and that no heading indication was available. During the subsequent flight phase, significant oscillations in attitude occurred and the rate of climb and descent, as well as the aircraft's airspeed, var- ied considerably. The air traffic control officer (ATCO) guided the aircraft with left/right in- structions into a position for a repeated approach. In addition, arriving and departing traffic on Zurich Airport was halted in order to provide flight LX 5187 with optimal support.
In accordance with the abnormal checklist, the crew switched the EFIS selector to the "BOTH 2" position and at 09:58:52 UTC reported that they would shortly have the indications available again.
A little later the ATCO gave clearance for an approach on runway 14 and the crew, who had reengaged the AT and the FD, reported at 10:03:21 UTC that they were "fully established". The approach was carried out manually.
The subsequent final approach and landing were uneventful.
Causes
The serious incident is attributable to the fact that after the failure of a single system the crew did not use the remaining systems appropriately and safe control of the aircraft was at times no longer guaranteed.
The investigation identified the following factors which led to the serious incident:
- The crew had a fundamentally unfounded picture about the technical problem causing the system failure.
- After the loss of the autopilot, autothrottle and flight director, the copilot did not manage to continue to control the aircraft manually.
- The commander was able to fly the aircraft only to a limited extent with the aid of the standby instruments.
- Crew resource management (CRM) was unsatisfactory.
- The crew did not carry out a sufficient analysis of the situation.
- An exercise which had been practised in the simulator using standby instruments and raw data could only be partially implemented in the actual case.
hahemmm....so they knew that they
might have an AT/AP/FD problem.... thats a crew of a well respected airline?
A capt with 9400hrs of nearly 4000 on type? The F/O with 1500/1000 on type?
Woah.