Aviation safety issues and actions

Dual-point restraints

Issue number: AO-2014-053-SI-03
Who it affects: Parachute aircraft owners
Issue owner: The Civil Aviation Safety Authority (CASA) and the Australian Parachute Federation (APF)
Transport function: Aviation: General aviation
Background: Investigation Report AO-2014-053
Issue release date: 23 June 2017
Current issue status: Closed – Not addressed
Issue status justification:

While both CASA and the APF have highlighted the issues surrounding dual point/dual release systems, there has been no attempt to redesign the system to address these limitations. Rather, the ineffective single point restraint system is permitted to continue in service, putting parachutists at increased risk of injury.

Safety issue description

Research has identified that rear‑facing occupants of parachuting aircraft have a higher chance of survival when secured by dual-point restraints, rather than the standard single-point restraints that were generally fitted to Australian parachuting aircraft.

Response to safety issue by the Civil Aviation Safety Authority (CASA)

The immediate survivability in a number of specific crash scenarios may be increased by the use of dual-point restraints. However, other possible scenarios requiring rapid emergency egress from an aircraft should also be taken into account. Survivability in possible scenarios, such as an emergency landing or crash into a body of water (e.g., ATSB Aviation Occurrence Investigation 200600001, Collision with terrain, Cessna U206, VH-UYB, Willowbank, Qld, 2 January 2006), post-crash fire (AO‑2014-053, Collision with terrain involving Cessna U206G, VH-FRT, Caboolture Airfield, Qld, 22 March 2014) or the immediate emergency evacuation of passengers who are in an injured or non‑conscious state should also be examined. The usage of dual-point restraints in these post-crash scenarios may impede the rate that the emergency evacuation may be completed thus presenting additional risks as identified in the survival aspects section of this report.

The differing aircraft types utilised in parachuting operations in Australia also needs to be taken into account when examining the possible usage of dual-point restraints. With reference to Sport Parachuting, United States Federal Aviation Administration (FAA) Advisory Circular AC105-2E Appendix 3 (Seats and Restraint Systems) depicts an aircraft equipped with quick release track fittings. This type of floor mounted fitting, although standard in many large, turbine-powered aircraft such as the Cessna Caravan and Twin Otter, are not fitted to all aircraft. Smaller piston-powered aircraft in use for parachute operations, such as the Cessna 182 or 206, do not have these floor mounted fittings. In these types of aircraft the restraints need to be fitted to suitable anchor points, which may or may not be located at convenient loading points for the operation.

The anchor points used to secure the restraints in these smaller aircraft types are generally those approved by the aircraft manufacturer as the original seatbelt or seat mounting points. An STC [supplemental type certificate] owned by the APF [Australian Parachute Federation] allows certain models of Cessna 182 aircraft to operate with a total of 6 POB providing the MTOW is not exceeded. To allow this the STC requires an appropriate number of single-point restraints (SPRs) to be fitted to specific attachment points in the aircraft cabin. Any additional requirement to use dual-point restraints would double the number of attachment points required which would increase the compliance costs. CASA is required to take all relevant considerations, including cost, into account.

The research conducted into the use of dual-point restraints stems from a Twin Otter Skydiving Aircraft accident in the USA on 29 July 2006 (NTSB/AAR-08/03/SUM).

The NTSB Aircraft Accident Summary Report contained the following safety recommendations:

The National Transportation Safety Board recommends that the Federal Aviation Administration:

Conduct research, in conjunction with the United States Parachute Association, to determine the most effective dual-point restraint systems for parachutists that reflects the various aircraft and seating configurations used in parachute operations. (A-08-71)

Once the most effective dual-point restraint systems for parachutists are determined, as requested in Safety Recommendation A-08-71, revise Advisory Circular 105-2C, Sport Parachute Jumping, to include guidance information about these systems. (A-08-72)

The National Transportation Safety Board recommends that the United States Parachute Association:

Work with the Federal Aviation Administration to conduct research to determine the most effective dual-point restraint systems for parachutists that reflects the various aircraft and seating configurations used in parachute operations. (A-08-73)

Once the most effective dual-point restraint systems for parachutists are determined, as requested in Safety Recommendation A-08-71, educate your members on the findings and encourage (edited to add emphasis) them to use the most effective dual-point restraint systems. (A-08-74).

Response to safety issue by the Australian Parachute Federation (APF)

Regarding the use of dual‑point restraints, the Australian Parachute Federation (APF) stated:

…APF believes that the use of dual restraints will not result in a net improvement in safety due to additional complications. These include dealing with inexperienced or tandem parachutists in relation to in flight emergencies and the ability to disconnect them quickly and safely in reaction to an emergency…

Australian Transport Safety Bureau (ATSB) response:

The ATSB acknowledges the concerns of CASA and the APF regarding egress following an accident. However, occupants of an aircraft must first survive the accident and remain conscious in order to extricate themselves and/or others. Research shows that this is more likely to occur if dual‑point restraints are used for rear facing parachutists.

The Federal Aviation Administration (FAA) provided educational material to those engaged in parachuting in the form of advisory circular AC 105-2E (appendix B). That document has reference material which can and has been used by the industry in an effort to enhance safety. It provides guidance:

…to improve sport parachuting safety and disseminates information to assist all parties associated with sport parachuting to be conducted in compliance with Title 14 of the Code of Federal Regulations (14 CFR) part 105…

Appendix 3 to that circular states:

(3) Single point, single tether restraints are not recommended.[emphasis added]

(4) Dual point, dual tether restraints offer superior restraint compared to single point, single tether restraints. This restraint method consists of two straps, each connecting the parachute harness to the aircraft floor on both sides of the parachutist…

While the FAA have not made the use of dual‑point restraints mandatory, they have provided guidance to industry that clearly shows that single point restraints are an inferior restraint option. As a result, the ATSB has issued the following safety recommendation to the Civil Aviation Safety Authority.

ATSB comment:

As detailed above, given the identified safety benefit offered by dual point restraints, the ATSB issues the following safety recommendation.

Safety recommendation

Action number: AO-2014-053-SR-018
Action organisation: Civil Aviation Safety Authority (CASA)
Date: 23 June 2017
Action status: Released

The ATSB recommends that the Civil Aviation Safety Authority, in conjunction with the Australian Parachute Federation, takes action to increase the usage of dual‑point restraints in parachuting aircraft that are configured for rear facing occupants

Additional correspondence

Response date: 17 August 2017
Response from: Civil Aviation Safety Authority
Action status: Monitor
Response text:

It is acknowledged that an occupant must first survive an accident and be conscious to enable their extrication from the aircraft. Similarly, CASA recognises the research conducted by the FAA Civil Aviation Medical Institute (CAMI) regarding parachutist restraint and the recommendation for dual point restraints. However, CASA must also give consideration to all aspects of accident survival, such as:

  • A fundamental design philosophy for all occupant restraint systems is the use of a single point release. The introduction of dual point restraints will most likely introduce a two point release of the restraint unless the system is extremely complex;
  • In the event of evacuations for lesser impacts, which are likely to occur more often, a single point restraint may be adequate. In such instances, the use of dual point restraints would involve increased effort and time to evacuate that may be critical;
  • Delaying or complicating evacuation from a low level bail-out i.e. engine failure after take-off where the additional actions necessary to release dual point restraints could increase the risk of injury as a result of closer proximity to the ground at the time of exiting the aircraft and
  • Finally, dual point restraints will greatly increase the number of potential snags present in an aircraft interior.

CASA will continue to investigate all options and technology associated with parachutist restraint including a review of CAO 20.16.3 Air service operations - Carriage of persons, which currently uses prescriptive language that restricts parachutist restraint options.

ATSB comment date: 21 September 2018
ATSB comment:

Australian Transport Safety Bureau

As per the ATSB’s previous response, the potential for dual-point restraints to complicate evacuation in the event of an emergency is recognised. However, the testing conducted by the Civil Aerospace Medical Institute, supported by the Federal Aviation Administration Advisory Circular AC 105-2E Appendix 3, concluded that dual‑point restraint systems were superior to single‑point restraints and that single‑point restraints was specifically not recommended for use.

The ATSB notes that CASA intends to ‘…continue to investigate all options and technology associated with parachute restraint…’. While continued research in this area is welcomed, in the absence of any information regarding the scope and/or timeline associated with such investigation, it is not possible to assess whether any associated safety action arising from CASA’s investigations will adequately address the safety issue.

The ATSB notes that a Coronial inquest relating to the accident involving VH‑FRT will be conducted in September 2018. That inquiry will provide a valuable opportunity to further consider this safety issue, including its resolution. As such, it will remain open until the conclusion of the Coronial proceedings.

Safety recommendation

Action number: AO-2014-053-SR-019
Action organisation: Australian Parachute Federation (APF)
Date: 23 June 2017
Action status: Monitor

The ATSB recommends that the Australian Parachute Federation, in conjunction with the Civil Aviation Safety Authority, takes action to increase the usage of dual point restraints in parachuting aircraft that are configured for rear facing occupants.

Additional correspondence

Response date: 17 August 2017
Response from: Australian Parachute Federation (APF)
Action status: Monitor
Response text:

The APF's Aviation Committee and Technical & Safety Committee both reviewed restraints used in parachuting Operations and formally found at their meetings on 31 October 2017 and 7 November 2017. We support Single Point Restraints (SPRs) as the safest all-round restraint system for parachuting operations in Australia.

This was based on the following considerations:

  • SPRs restrain rear-facing, floor-seated parachutists and adequately prevent load shift.
  • APF has no recorded incident that shows lack of strength involving a SPR.
  • DPRs [Dual Point Restraints] are acknowledged as stronger than SPRs. It must be noted that stronger restraints are available in both passenger aircraft and domestic motor vehicles but are not always adopted due to practicability and other potential risk factors.
  • APF have implemented an improved SPR since the Caboolture aircraft fatalities (Model G025).
  • SPRs by their nature use a single-point release (one action, by one hand). DPRs for parachuting operations require dual-point release. APF supports single point release so that they can be operated quickly with one hand in an emergency and/or due to incapacitation.
  • APF typically use small civilian aircraft such as 182, 206 and 208. These are not wide body and two rows of skydivers provide little room between for restraint operation. This restricted space does however provide an advantage in reducing the chance of occupants twisting or rotating in the event of rapid deceleration whilst connected by a SPR to one side of the occupant's torso.

DPRs add inherent risk:

  • Due to delay in releasing in: fire prior to take off, low level emergency evacuation, ditching or fire after emergency landing situations.
  • Adding a second restraint to each parachutist would increase risk in the event of a premature deployment of a parachute in flight.
  • Doubling the number of restraints secured to the floor area significantly increases snag point hazards to exiting parachutists that could result in hang-ups under the aircraft.
  • Testing has found DPRs particularly cumbersome when briefing tandem students. The ability for student parachutists to manage release and un-threading of a DPR is of great concern.

APF acknowledge that in the Caboolture aircraft crash, there is doubt that SPRs were being worn. Non use of SPRs is in contravention of APF regulations. APF believes any non-use is very isolated and has since reinforced their use across the sport. The new G025 SPRs are now installed and in use in all jump aircraft across Australia.

Summary

Unlike all other aircraft operations, in parachuting operations, the intention of those onboard (except the pilot) is always to exit the aircraft (not to be restrained).

Despite the USA FAA AC 105-2E general information on DPRs, we are not aware of any civilian skydiving organisation in the world using DPRs.

ATSB comment date: 21 September 2018
ATSB comment:

Australian Transport Safety Bureau

The ATSB acknowledges that the Australian Parachute Federation (APF) remains concerned that the use of dual‑point restraints may introduce additional egress risks to occupants during parachuting operations compared to those associated with single‑point restraints. On that basis they have rejected the safety issue identified by the ATSB.

However, to date the APF has not provided any information that would enable the relative egress risk between single‑ and dual‑point restraints to be reliably quantified. In the absense of such an assessment, it is unclear on what basis the APF has concluded that the risk posed by dual‑point restraints outweighs the benefits identified by Civil Aerospace Medical Institute (supported by the Federal Aviation Administration Advisory Circular AC 105-2E Appendix 3).

The ATSB notes that a Coronial inquest relating to the accident involving VH‑FRT will be conducted in September 2018. That inquiry will provide a valuable opportunity to further consider this safety issue, including its resolution. As such, it will remain open until the conclusion of the Coronial proceedings.

Response from: Coroner
Action status: Closed
Response text:

Coroner

In response to the ATSB recommendation on dual-point restraints the Coroner stated the following:

The ATSB report contained a recommendation directed at CASA and the APF in relation to the use of dual point restraints.

In this inquest, it was clear that the question of the type of restraint fitted on FRT did not directly impact upon the manner and cause of death of the deceased. The recommendations of the ATSB are relevant to the wider issues that the ATSB has canvassed in its report.

ATSB comment date: 06 November 2020
ATSB comment:

Australian Transport Safety Bureau

During the Coronial inquest into the FRT accident, the Queensland State Coroner stated that single point restraints fitted to FRT did not directly impact upon the manner and cause of death of the occupants. Therefore, the Coroner did not expressly stipulate a recommendation or finding in the area of dual point restraints. However, significant testimony was delivered during the Coronial inquest along the lines of the ATSB, CASA and APF comments about the recommendation.

The ATSB conveyed its position in the FRT report and in the Coronial testimony about dual point restraint for rear facing occupants, which is summarised as follows:

  • Single point restraints significantly increase the chances of flail type injuries in the event of an aircraft accident when compared to dual point restraints.
  • Based on detailed crash test research data (NTSB investigation AAR-08-03), single point restraints do not offer an effective means of restraint.
  • Based on the NTSB research the United States Federal Aviation Administration Airworthiness Circular AC 105-2E states that:
    • Single point, single tether restraints are not recommended.
    • Dual point, dual tether restraints offer superior restraint compared to single point, single tether restraints.
  • Although single point restraints have shown significant deficiencies during testing, they are better than no restraint at all, as they limit occupant movement preventing load shift.

The APF and CASA position about dual point restraints for rear facing occupants was similar and therefore can be conveyed together in the summary below:

  • The FAA encourages, rather than mandates the use of the most effective dual point restraint system for use by parachute organisations
  • Dual point restraints increase the amount of time taken for an occupant to extricate themselves from an aircraft in the event of an accident, due to increased complexity of the dual release mechanisms. This may increase the risk of post-accident survival in situations such as post-accident fire or collision with water.
  • Dual point restraints will greatly increase the number of potential snags present in an aircraft interior.
  • The use of dual point restraints would double the amount of anchor points required, which would increase compliance costs.

ATSB assessment:

It is clear based on detailed research that single point restraints do not offer a requisite level of protection for rear facing occupants of parachute aircraft. It is also recognised that the same research does not take into consideration the issues highlighted by CASA and the APF with regards to dual point restraints. The ATSB accepts the position taken by CASA and the APF that dual point/dual release restraints of the style tested pose an increased risk in some post‑accident survival scenarios. The ATSB also accepts that the other issues highlighted by CASA and the APF are valid concerns. However, while recognising that dual point/dual release system have limitations, the ATSB remains of the view that dual point restraints for rear facing occupants remains the safest option.

The NTSB and the FAA both recognise that single point restraint systems are ineffective and increase risk of serious injury in the event of a significant parachuting accident. CASA and the APF also recognise that single point restraints do not secure and protect an occupant as well as dual point restraint systems. While they have highlighted the issues surrounding dual point/dual release systems, there has been no attempt to redesign the system so that the issues could be improved. Rather, the ineffective single point restraint system is permitted to continue in service, putting parachutists at increased risk of injury.

Given the issues about dual point restraint systems highlighted by CASA and the APF, it is important that they, in CASA’s words:

’… continue to investigate all options and technology associated with parachutist restraint…’

The ATSB encourages CASA and the APF to conduct research and development in the area of improved restraint systems for parachutists.

Last update 06 November 2020