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IAVWOPSG/4-WP/26
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International Civil Aviation Organization
WORKING PAPER / IAVWOPSG/4-WP/26
19/6/08

INTERNATIONAL AIRWAYS VOLCANO WATCH OPERATIONS GROUP (IAVWOPSG)

FOURTH MEETING

Paris, France, 15 to 19 September 2008

Agenda Item / 5: / Operation of the IAVWOPSG
5.3: / Consideration whether the smell of sulphur be a condition prompting the issuance of a special air-report

MATERIAL RELATED TO THE SMELL OF SULPHUR AT CRUISE ALTITUDE FOR THE USE OF FLIGHT CREWS

(Presented by Australia, United States (Rapporteur), IATA, IFALPA and IUGG))

SUMMARY
This paper recommends draft guidance language for inclusion in ICAO Doc 9766, Handbook on the International Airways Volcano Watch, Operational Procedures and Contact List for the reporting of and responding to sulfurous gas such as sulphur dioxide (SO2) at cruise altitude as a follow-up of Conclusion 3/21.

1.INTRODUCTION

1.1At the third meeting of the International Airways Volcano Watch Operations Group there was discussion on the need to develop guidance material related to the smell of sulphur at cruise altitudes. Conclusion 3/21 specifically tasks an ad hoc working group to assess the smell of sulphurous gases as an indicator of the presence of volcanic ash in the atmosphere.

1.2The group has met with some success in this assessment but there is still much more work to be done. What appears to be obvious is not necessarily the situation. This paper will highlight some of the issues that this group has been struggling with and proposes a first step in providing some type of guidance to flight crews.

2.Discussion

2.1Based on a review of existing available documentation that is easily accessible, there is limited or practically no procedure to advise flight crews that when they detect SO2 at cruise altitude they may be entering an volcanic plume. While much of this has been discussed over the years, the knowledge is limited to those who fully understand the association of SO2 with ash. The presence of SO2 is not a guarantee that volcanic ash is also present, but for a pilot to ignore the possibility that volcanic ash maybe present, do so at great risk.

2.2Pilots are trained to understand that the sensitivity to odors in flight is paramount to the safety of flight. The first discernment is whether the odor is generated from inside or outside the aircraft. Two odors that are described as somewhat similar are “Electrical Smoke and Fire” and SO2. Electrical Smoke and Fire has a deadly history and that odor remains as long as there is smoke and fire. SO2, best described as a sulfur odor similar to a struck match will only be detectable for a short period because the presence of sulfurous gases can lead to olfactory fatigue, (overloaded nerve receptors), resulting in the inability to smell the odor of SO2. Based on an in flight crew report, the breathing of 100% oxygen returns the ability to smell SO2 thereby allowing the crew to verify they are still in an SO2 cloud.

2.3In reviewing a select number of airline OPS SPECS, the following procedure is typically put into place. At the direction of the captain, the flight crew should don an oxygen mask and breathe 100% oxygen for a short period to regain the ability to smell the SO2 with the principal aim to determine the cause of SO2, specifically if there is a fire on board. Guidance on SO2 and its possible association with volcanic ash is lacking in general for most OPS SPECS. Therefore, it is recommended that the OPS SPEC provide some guidance to the captain after it is ascertained that there are no other sources of SO2 from onboard the aircraft. Attachment A provides a draft for inclusion in ICAO Doc 9766 on response to be taken by pilots in the event of entry into a SO2 cloud. However, it needs to be understood by the group that inclusion of any type of guidance of OPS SPEC is a function of a State’s regulator. Attachment ‘A’ is model example of what can be considered for inclusion. The regulator makes a final determination of what can be included in the OPS SPEC with regard to SO2.

2.4While this paper has focused on the issues associated with the detecting of SO2 with a proposal on guidance for pilots for what to do if SO2 is observed on the flight deck, it should not be forgotten that ICAO has provided training material and posters on what pilots are to do if they encounter an ash cloud. Please see the working paper on the ‘availability of training video on volcanic ash’ that makes reference to the most current training material available.

3.Conclusion

3.1Considering that there is a need to provide guidance on the detection of sulfurous gases for the flight crew the following draft conclusion is proposed:

Conclusion 4/xx ― / Guidance to pilots on the detection of sulfurous gases on the flight deck
That the Secretary be invited to include the guidance on practices that can be followed by pilots on the flight deck regarding the detection of sulfurous gases for inclusion in ICAO Doc 9766, Handbook on the International Airways Volcano Watch Operations Procedures and Contact List
Note: The Secretary needs to include Doc 9766, a qualifying statement that this is an example of a practice and does not necessarily reflect other practices that are used by operators

4.ACTION BY THE IAVWOPSG

4.1The IAVWOPSG is invited to:

a)note the information in this paper; and

b)decide on the draft conclusion proposed for the group’s consideration.

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A-1 / IAVWOPSG/4-WP/26
Appendix
IAVWOPSG/4-WP/26
Appendix

APPENDIX

Attachment A

DRAFT TEXT REGARDING ACTION & RESPONSE TO BE TAKEN

BY PILOTS IN THE EVENT OF ENTRY INTO A SO2 CLOUD FOR INCLUSION IN THE IAVW HANDBOOK (Doc9766)

. . .

4.6RECOMMENDED ACTION & RESPONSE TO BE TAKEN BY PILOTS IN THE EVENT OF ENTRY INTO A SO2 CLOUD

4.6.1The presence of a sulfurous gas, (SO2) at altitude is the result of volcanic activity. SO2, best described as a sulfur odor similar to a struck match will only be detectable for a short period because of the olfactory fatigue resulting in lose of the ability to smell the odor of SO2. Sensitivity to odors while in-flight is paramount to the safety of flight. “Electrical Smoke and Fire”and SO2 are two odors that are described as somewhat similar requiring a means to verify which odor is present.

4.6.2After determining there are no secondary indications that would result from and indicate an electrical fire, the crew should continue to determine the source of the odor. The first decision by the crew is to establish whether the odor is generated from inside or outside the aircraft. In order for the crew to make this determination and confirm if the odor is transient or not, at the direction of the captain, a crew member should don an oxygen mask and breathe 100% oxygen for the period of time that results in a complete change of air within the cockpit.

4.6.3The crew member should breathe 100% oxygen for the length of time determined in 4.6.2 to regain the ability to smell the SO2. After the appropriate time period, the crew member should remove their oxygen mask and determine if the odor is still present. If the crew member affirms the continued presence of SO2, it is recommended the captain report their findings to the controlling ATC facility and company dispatch as soon as practicable.

4.6.4It is recommended the reporting pilot use the Volcanic Activity Report form (VAR) Section 1, Items 1-8. Following the submission of the VAR, the crew should remain vigilant for signs of inadvertent entry into a volcanic ash cloud. The crew should also request periodic updates of any volcanic activity along their route of flight from the controlling ATC facility and company dispatch.

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