A recent letter to Flight International commented on the MD 11 incident and queried why the crew did not check the ILS, a point amongst others omitted, or apparently not considered in the report.
This is a good example of the difficulties investigators experience when considering the human factors contributions to events; ‘why didn’t they …’ etc. Most difficulties stem from ICAO requirements restricting the conclusions to factual evidence. However, it could be argued that this limits the industry benefiting from many Human Factors lessons to be learnt from these investigations, especially where some speculative discussion might prompt operators to consider – ‘that could happen to us’, although it could not be proven in the incident.
Further consideration of why the MD 11 incident did not involve an EGPWS warning as observed by Safetypee might elicit some interesting viewpoints.
The aircraft was approximately 700 ft a.g.l. which would be at the edge of the EGPWS terrain alerting boundary at longer ranges from the runway, but within the boundary as the aircraft continued the approach. So why no warning?
The aircraft may not have been fitted with EGPWS. Given that US registered cargo aircraft do not have to fit EGPWS raises a point of commercial advantage, but also for safety, should the CAA be equally concerned about saving life on the ground as well as in the air. Although the aircraft probably had the ‘old’ GPWS, during an approach with the gear down, then no terrain related alerts are given. If the weather/vis had been marginal, then the aircraft could have encountered terrain near the village of Kegworth!
Additional speculative investigation could also have consideration that instead of the crew forgetting the change from the standard altimeter setting (1013hp) to the QNH of 974hp, they actually set 29.74in (close to 29.93/1013 std). This error could easily result through reversion to the US habit of clipping/abbreviating the value of the pressure setting during read-back, i.e. 974 instead of 29.74. This could also answer why the crew appeared adamant that the QNH was set when queried by ATC. Then add fatigue – a route involving a US-Europe time change then from Europe to the UK arriving at 0200 local… etc, etc.
A little speculative discussion in the AAIBs reports could add significant safety value.