Size Isn’t Everything

The day after the Civil Aviation Authority (CAA) CAP1145 report on North Sea helicopter safety was published, the Aberdeen Press & Journal focused on one controversial action with the front page headline ‘If you are too fat you won’t fly’!

But when it comes to escaping from a submerged helicopter through the push out windows, it seems size really isn’t everything.

The CAA action that grabbed the headlines was the prohibition of passengers ‘whose body size, including the required safety and survival equipment, is incompatible with push-out window emergency exit size’ from April 2015 (CAP1145 Action 9) and was the subject of a presentation at a recent seminar (discussed by Aerossurance here).

Oil & Gas UK had already initiated an offshore workforce ‘Size and Shape’ study by Robert Gordon University (RGU) in 2011.  The study was designed to support a range of health, safety and ergonomic studies, scanning a target of 600 volunteers.  So far 450 people have been scanned with 150 more  volunteers being sought in further testing in June 2014 in Aberdeen and Norwich. Measurement to date has confirmed a 19% increase in average weight of the offshore population since a 1985 study, by Robert Gordon Institute of Technology (the forerunner of RGU).

3D Body Scanning (Credit: RGU)

The new RGU study was not just about weight though and also looked at body dimensions with and without survival equipment using modern 3D scanning technology. It was found that the full suite of survival equipment increases the body volume by an average of over 70%.

The RGU study received close attention from a new Oil and Gas UK working group tasked with assessing emergency egress and the practical implications of any type of passenger ‘body size’ limitations. Early work suggests that’s the ability to egress is not simply a matter of waist size as the press headlines may have suggested.  It is possible that some board shouldered body builders may have as much difficultly as the most ‘portly’ of passengers. As part of the working group’s activities the size of push-out window apertures across all in-service types are being physically measured by joint industry / CAA team, to create a central repository of this data.

Another goal for this working group is to achieve an industry wide ‘clothing policy’ on the number and type of layers of clothing worn under the survival suit. Currently there are variations between different oil companies and whereas multiple layers give valuable insulation after an escape, they could hinder an escape for some. The working group aims to make recommendations in October 2014.

UPDATES Other legal complexities emerged in August 2014: Overweight workers could cost offshore industry

Oil & Gas UK are staged a briefing on 26 August 2014: Recipe for a Healthy Workforce

Oil & Gas UK produce this annual report: Offshore Workforce Demographics

UPDATE 2 September 2014: The Helicopter Safety Steering Group (HSSG) has confirmed that:

  • The RGU Size and Shape Study is complete.
  • The Workgroup has decided that passengers will be measured by the width of their shoulders, not by BMI or weight.
  • Details are to be announced of a new Standard Clothing Policy that will be introduced on 1 October 2014.

UPDATE 10 September 2014: The new clothing policy is described here.

UPDATE 6 October 2014: Helicopter safety: It’s your frame size that matters . . . broadly speaking This article describes the concept of ‘Extra Broad’ / XBR passengers (those of over 22″ [56cm] i.e. shoulder dimension) who will reportedly be limited to 25-30% of the available seats, next to a Type IV exits (26” x 19”).  We understand that a chest depth of over 14″ will also result in an XBR classification being added to the Vantage Person on Board (POB) system.

Passenger Size (Credit: Step Change in Safety)

Coincidentally 22″ is the theoretical diagonal across a 17″” by 14″ aperture (theoretical as most windows have rounded corners).  Leaflet 44-30 Helicopter Emergency Escape Facilities of CAA CAP562 Civil Aircraft Airworthiness Information and Procedures (CAAIP) is the latest CAA document to state a conclusion from the mid 1980s that:

Underwater escape through a rectangular aperture of 17” x 14” (432mm x 355mm) has been satisfactorily demonstrated by persons of a size believed to cover 95% of male persons wearing representative survival clothing and uninflated lifejackets.

UPDATE 14 October 2014: Step Change in Safety Passenger Size FAQs and CAA Operational Directive.

UPDATE 8 January 2015: Step Change have announced that offshore medics will do the measurements (see this presentation and this FAQ list).

UPDATE 24 January 2016CAP1145 Helicopter Water Impact Survivability Statistics – A Critique

UPDATE 12 February 2016: Video: The North Sea size and shapes impact on helicopter escape potential

Aerossurance has extensive helicopter safety, operations, airworthiness, risk management, survivability and accident analysis experience.  For helicopter advice you can trust, contact us at:

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