M1A – Strategic mitigation – sheltering
AMC1 Article 11 Annex B. M1A Strategic mitigation – sheltering
CAA ORS9 Decision No. 46
M1A Sheltering – Level of integrity
| Criterion | Low | Medium | High |
|---|---|---|---|
| Criterion 1 (Evaluation of people at risk) | M1A.C1.L.I |
M1A.C1.L.I M1A.C1.M.I |
Not applicable |
| Criterion 2 (Evaluation of penetration hazard) | M1A.C2.L.I |
M1A.C2.L.I |
Not applicable |
M1A Sheltering – Level of assurance
| Criterion | Low | Medium | High |
|---|---|---|---|
| Criterion 1 (Evaluation of people at risk) | M1A.C1.L.A |
M1A.C1.L.A M1A.C1.M.A |
Not applicable |
| Criterion 2 (Evaluation of penetration hazard) | M1A.C2.L.A |
M1A.C2.L.A |
Not applicable |
Low level of robustness
M1A.C1.L.I
Criterion 1- Evaluation of people at risk
If the applicant claims a reduction in ground risk due to a sheltered operational environment, the applicant must:
(a) Only fly over operational environments which generally consist of structures providing shelter.
(b) Verify that they reasonably expect uninvolved people will be located under or inside a structure.
This mitigation may not be applied when only overflying open-air assemblies of people or areas with no shelter.
M1A.C2.L.I
Criterion 2 – Evaluation of penetration hazard
The applicant must use a UA that is not expected to penetrate structures and fatally injure people under the shelter.
M1A.C1.L.A
Criterion 1- Evaluation of people at risk
(a) The Applicant must provide evidence of compliance with the integrity requirements.
(b) The evidence should be in the form of a report that describes that the operation is in an environment that has structures providing shelter where people are generally expected to be, and the applicant does not fly over large open-air assemblies of people.
M1A.C2.L.A
Criterion 2 – Evaluation of penetration hazard
The applicant must submit a declaration of compliance that the UA used is under 25 kg MTOM.
OR
For UA with MTOM higher than 25 kg, the applicant must provide compliance evidence that the required level of integrity is achieved. This should be a report detailing testing, analysis, simulation, inspection, design review or through operational experience.
Medium level of robustness
Lower robustness level requirements to be complied with:
• M1A.C1.L.I
• M1A.C2.L.I
• M1A.C1.L.A
• M1A.C2.L.A
Additional requirements to be compiled with:
M1A.C1.M.I
Criterion 1- Evaluation of people at risk
(a) Same as low. In addition, the applicant must restrict operating times and demonstrate that an even higher proportion of uninvolved people are sheltered.
M1A.C2.M.I
Criterion 2 – Evaluation of penetration hazard
No additional requirements.
M1A.C1.M.A
Criterion 1- Evaluation of people at risk
(a) Same as Low. In addition, the applicant must have time-based restrictions in place and provide compliance evidence to support that a higher proportion of people are sheltered.
Medium robustness M1(A) mitigation may not be combined with M1(B) mitigations.
M1A.C2.M.A
Criterion 2 – Evaluation of penetration hazard
No additional requirements.
GM1 Article 11 Annex B. M1A Strategic mitigation – sheltering
CAA ORS9 Decision No. 46
GM.M1A
M1(A) mitigation relies on the fact that people spend on average very little time outdoors without protection from structures. Therefore, operators of sufficiently small UAS may expect that a large percentage of the population will be sheltered from potential impacts. For larger UAS, the effectiveness of this sheltering assumption must be demonstrated.
Time-based arguments, such as the claim that flying at night reduces risk because fewer people are outdoors, are not applicable at low robustness. However, these arguments are included at medium robustness.
Sheltering at low robustness is considered a generally applicable mitigation based on the environmental characteristics where the UAS is operated. This mitigation does not involve any additional operational restrictions. To avoid double counting, M1(A) medium robustness mitigations may not be combined with any M1(B) mitigations. In contrast, M1(A) low robustness, which has no operational restrictions, may be combined with M1(B) mitigations.
GM.M1A.C1.L.I
(a) The consideration of this mitigation may vary based on local conditions. The intention is to estimate the proportion of people outside on average and not at a specific time of day or year. There will be times when at specific locations temporarily there are more people exposed, but it should be sufficient to expect that on average the proportion of people exposed outside is below 10%.
GM.M1A.C2.L.I
Guidance on how to evaluate sheltering effect can be found from:
(a) ASSURE UAS Ground Collision Severity Evaluation A4 report section "4.12. Structural Standards for Sheltering (KU)", pages 103 to 111, or
(b) MITRE presentation given during the UAS Technical Analysis and Applications Centre (TAAC) conference in 2016 titled ‘UAS EXCOM Science and Research Panel (SARP) 2016 TAAC Update’ - PR 16-3979.
In general, it may be expected that UAS weighing less than 25 kg are not able to penetrate buildings except in rare cases where the UAS speed or building materials are unusual (tents, glass roofs, etc).
GM.M1A.C1.L.A
(a) For example, a city or town consists generally of structures providing shelter. While it may also include areas that are not sheltered, the mitigation is expected to be provided in most of such cases.