The Sea King attrition saga*

* Moderator’s Note: This is an excerpt of an article originally published in Airforce Magazine, (Winter, 2008): 11 – 16. It is reprinted here with the permission of the publisher.  The article provides an analysis of the fates of the lost Sea Kings.  My thanks to Christine Hines, Curator at the Shearwater Aviation Museum, for bringing the article to my attention.  You can read a full version of it here.

As the Maritime Helicopter community reflects on 40 years of CH-124 Sea King operational service, one sobering thought relates to the fact that only 27 of 41 original aircraft remain on the Canadian Forces inventory.  Catastrophic accidents have claimed a total of 14 aircraft since the helicopter first entered military service in the mid-1960s, together with the loss of seven naval aviators.  Given the unforgiving nature of low-level maritime aviation, and the unsavoury maritime elements, a 33 percent aircraft attrition rate over such a long period could be viewed as impressive on one hand, yet offer some cause for reflection on the other.

Calamitous aviation accidents tend to assume mythical proportions over time, ultimately become distorted through rumour, gossip and innuendo.  Initially, the purpose of this article was merely to chronicle the circumstances surrounding each missing Sea King aircraft to distinguish fact from fiction.  As the data was being compiled and reviewed, however, some intriguing trends began to emerge in the form of statistical tendencies that could prove germane to future MH operations. Finally, and perhaps most importantly, the article shall bear testament to those who offered up their lives in selfless service to their nation.

The 40-Year Saga (1969-2007).  A snapshot synopsis of the 14 major Sea King accidents is provided in Table 1.  This lists each aircraft loss in chronological order along with pertinent investigative details.  An amplifying narrative of each accident has also been provided, gleaned through factual information contained within military post-accident reports.  [See the full version for these details and two additional tables.]

Table 1 – CH-124 Sea King Attrition




Accident Location



Cause (Primary)

1 402 Nov 67 At Sea No 2 Pilot - Fatigue
2 427 Feb 68 At Sea No 0 Engine - Failure
3 415 Jun 69 At Sea No 0 Engine - Compressor
4 420 Nov 71 At Sea No 3 Engine - Failure
5 432 Nov 72 Shearwater N/A 0 Pilot – Tail Rotor Buzz
6 418 Apr 73 Off Halifax No 0 Engine - Failure
7 409 Nov 87 Off Halifax Yes 0 MGB – Chip Lights
8 411 Sep 89 At Sea No 0 MGB – Oil Loss
9 439 Aug 91 Schenectady, NY N/A 0 Pilot – Vortex Ring State
10 423 Feb 93 At Sea Yes 0 Electrical - Battery
11 425 Apr 94 Saint John, NB N/A 2 Engine - Fire
12 422 Jun 00 At Sea No 0 MGB – Overheat
13 401 Feb 03 At Sea Yes 0 Engine – Power Loss
14 438 Feb 06 At Sea Yes 0 Under Investigation

Trends N’ Thoughts.  Through an analysis of the catastrophic Sea King accident summaries assembled here, what conclusions, if any, can be drawn?  Does the accumulated accident data in fact offer up any relevant trends, thoughts or revelations that could impact or enhance the safety of future MH operations?   Some items for consideration are offered below, bearing in mind that statistics can often be manipulated to support many differing sides of the same argument.

It readily becomes apparent that engines, transmissions (MGB – Main Gear Boxes), and personnel input are the three primary cause ingredients related to Sea king attrition.  Should the argument be accepted that Sea King CH-423 might have been recoverable had the battery not been turned ‘OFF’ while in IMC, then the statistical results become even more dramatic.  Such findings tend to confirm the late-1990s NDHQ decision to upgrade the Sea King fleet with enhanced GE MK100 engines and 24000 series MGBs should be applauded by all members of the MH family.  Indeed, the documented evidence suggests that the improved engine and transmission programs most likely saved many aircraft and lives that did not have to be reflected in this accident summary.

While only seven human fatalities have been identified with the Table 1 accident summary review, eight airmen have actually been lost on Sea Kings over this 40-year period.  The eight aircrew fatality was a Naval Aircrewman, P1 (Royal Navy) Ron Greenbury, who was declared missing on Mar 22nd 1967 during a night low-level training mission in the Shearwater dip sectors.  Indicating that he was moving to the rear cabin area to investigate a fuel leak, the aircrewman disappeared – never to be seen again.  Despite an exhaustive search of the aircraft and the training area, no trace of the missing airman has ever been found.  His fate remains a mystery to the present day.

The Bottom Line.  A brief synopsis of the 40-year CH-124 Sea King accident record has revealed so intriguing trends that have characterized Canadian maritime rotary wing aviation throughout its evolution, as well as offered some potential warning signs for future MH operations.   Experienced aviators understand that there seldom are new accident cause factors: simply old familiar ones forgotten through the passage of time, apathy and/or complacency.  Certainly, relative to other air force fleets, the Sea King community has managed an impressive safety record over an extended 40-year operational period, particularly when on considers the inherent low flight profile and hazardous environmental conditions associated with the sea-going role.

There can be little doubt that engines, transmissions and human factors shall continue to challenge future Sea King operations, thus demanding a close and continuous watch over their status on a recurring basis.  Never has the demand for such oversight been greater than the present as the MH community prepares to take delivery of the more highly advanced, sophisticated and capable CH-148 Cyclones.