An aviation researcher, writer, aviation participant, pilot & agricultural researcher. Author of over 35 scientific publications world wide.


Good reads

Oil Prices


VFR Flight Report from CAA UK 2007 Helicopters Why was this not used in the ABC Chopper Report??

The following is a report on degraded helicopter flight from UK CAA. It makes very interesting reading.

A pity the ATSB could not have used this in the current ABC report, except to make a minor reference as follows:

A recent review conducted for the United Kingdom Civil Aviation Authority (2007) into helicopter accidents in degraded visual conditions stated:

At the heart of the high accident rate is the inherent instability of many small and some medium helicopters which can rapidly lead to excessive pilot workload when attempting to fly in degraded visual conditions.


In addition, inadvertent entry into cloud is more likely at night because the cloud is harder to see (United Kingdom Civil Aviation Authority 2007).

Really this is a very poor use of what is an excellent reference and the following example which is as follows, was never used in the final report. Instead there are examples of 747’s and other fixed wing aircraft, with dubious relevance.

Appendix A Detailed Accident Case Studies

1 Case 1 (SA355/199604787)

1.1 Synopsis

1.1.1 Overview: The aircraft was en-route with one pilot plus four passengers on-board.
The flight was carried out at night in visual contact with the ground, and the accident occurred during the execution of a climb to a higher altitude. During the climb, the pilot was deprived of external visual references, the aircraft entered an unintentional steep, nose-up attitude and lost airspeed. This manoeuvre developed subsequently into a fast, spiral descent from which the aircraft did not recover; it crashed into a field
and all occupants were killed.


1.1.5 Visual cueing aspects:

From subsequent flight tests carried out by the AAIB in the locality of the crash site, under night conditions with excellent visibility, no cloud and a full moon, it was ascertained that the following visual cueing factors would have played a role in the accident:

• After astronomical twilight there may be no true horizon.
• Minor terrain features could not be seen from the air from 1500-2000 ft above ground level.
• Optical perception of the horizon plane is provided by an illuminated ground plane.
• Unlit features such as rivers and roads were hard to see and follow and motorways
provide the best line features.
• The vicinity was unexpectedly dark because of the limited artificial lighting outside of towns.

1.2 Relevant causal factors and conclusions

• The pilot’s workload in marginal conditions was excessive.
• The pilot probably lacked recent experience of recovering the helicopter from an unusual attitude using flight instruments.
• The pilot was unable to control the aircraft by sole reference to flight instruments when external references were lost.
• The helicopter had no autopilot or autostabilisation equipment and was not approved for IMC operations.
• The flight had to operate below an overcast cloud layer, which was below the MSA.
• The flight had to avoid obstacles by detouring around them.
• The weather conditions were acceptable for attempting the flight.
• The lack of visual horizon was likely to become a problem where the cloud cover was overcast and the ground lighting was sparse.
• Immediately prior to the accident, the aircraft was in view of the ground and did not enter cloud.
• The helicopter adopted a steep, nose-up pitch attitude during the climb, during which the speed fell from 105 to 33 kn in 30 s.
• The excessive pitch attitude deprived the pilot of visual ground references and he subsequently became disorientated through losing external attitude references.
• Safe recovery from unusual attitudes depended on the pilot’s instrument flying skills.
September 2007


Question is: – Why did ATSB not use this particularly relevant case study by UK-CAA and the relevant AAIB reports in a more pro-active manner???

Night Operations – Canada Department of Defence

This also makes a useful read.