It is difficult to understand how the ‘leaked’ causes and recommendations have been assembled from the factual report. I assume that the missing parts of section 3 of the draft report will give an analysis and explain the logic used in the investigation, but on the data seen so far there appear too many illogical or flawed deductions.
I hope that the final report / investigators will address the following issues:
Did one or both propellers go into beta range during flight causing the aircraft to reduce airspeed (150-115), pitch nose down (-1 to -15), and loose altitude (2750 – 2100) such that the aircraft ultimately hit the ground? Thus this could have been a loss of control accident due to having reverse thrust in the air and ‘bunting’ (-0.5g) at low altitude. Following an apparent upset the crew may at a very late stage shut down one engine (fuel flow zero, LH prop rpm 5). Could they have encountered misleading power plant indications causing them to suspecting a failure? The crew appeared to be taking some corrective action – flap up and pulling nose up (less negative g: the elevator trace and lateral acceleration not shown).
A more extreme consideration would be that a pitch down after lowering flap is symptomatic of tail plane icing – recovery by pulling hard and retracting flap; is this to be formally discounted in the report?
What has not been clearly explained (or is not yet established / published) is why the propellers were in the beta range. Was this due to technical failure, or crew error in combination with a technical weakness (16 sec vulnerability when lowering the gear), or indeed a greater combination of these or other technical / organizational failures?
What is the logic in citing the crew’s late change of plan to continue the approach got to do with the cause other than they wished to slow down, they selected flight idle thrust, and lowered the flap and gear? If the technical weaknesses existed then the crew was just as vulnerable on this approach as any other.
Were the crew aware of the warnings about inadvertent or deliberate in-flight beta selections; how were they trained, did the documentation come with the aircraft?
Even with a comprehensive explanation and that in extremis the crew made an error, the rationale for the error must be presented before the recommendations can imply poor CRM or individual crew behavior. If the crew (crews) were inadvertently selecting beta in flight then an FDR monitoring program should have identified it, but so too would a LOSA program; furthermore LOSA would explain why the error was occurring. Deliberate, inadvertent, technical or a combination. Human error will occur in most operations; crews / organisations do not make errors deliberately, there is usually a complicated background to each event. What were the backgrounds to the errors in this accident?
I find it hard to understand why the anti skid manufacturer’s modification was only ‘optional’. Were they were more concerned about publishing that the mod was at the operator’s expense as opposed to closing down a safety weakness? It is not clear that the national authority mandated (must do) the mod, nor that they gave sufficiently strong advice about in flight beta awareness and avoidance training. Thus is an oversight program (Recc 4.3.1.1) equally applicable to the authority; as they audit the operators?
I hope that these points are answered with the publication of the final report. What the industry needs is information as to why crews make errors in emergency / unusual situations, not more reasons to blame them (and retrain them). The industry depends on the accident investigators to deliver this data.
Keep monitoring this thread.
Last edited by alf5071h; 22nd Nov 2003 at 02:36.