AAE5304 Chap.6 SORA Volumes, Buffers and Safety Distance
SORA Volumes, Buffers and Safety Distance
Each boundary represents a state
Flight geography contains normal operation. Contingency volume contains recoverable abnormal deviation. Ground risk buffer contains the expected end of flight after loss of control. Adjacent areas address fly-away beyond containment.
Build margins from physical causes
Horizontal contingency width adds positioning, map, reaction and manoeuvre allowances.
Vertical height adds flight-geography height, altitude error, reaction gain and contingency climb. Each term needs a unit and independent basis.
Recompute parachute drift
Impact mitigation can increase descent time and wind drift.
Ground-risk-buffer distance must therefore be recomputed rather than retaining a smaller one-to-one allowance.
Attach an action to each boundary
Normal navigation keeps the aircraft in flight geography. A detected excursion should trigger a recoverable contingency action within contingency volume.
When recovery is no longer credible, termination behaviour must keep the expected end of flight inside the ground buffer. Adjacent-area analysis addresses the rarer loss of containment.
Writing the trigger, action and expected state beside every boundary stops geometrical terms from being treated as interchangeable rings.
Audit each margin term
For every symbol, record value, unit, physical meaning, source, owner and conservative direction. Position uncertainty, mapping allowance, reaction travel and manoeuvre distance should enter once each.
If two terms describe the same uncertainty, adding both exaggerates the boundary without improving safety reasoning.
If a value changes with environment or aircraft state, identify the condition used and the evidence that makes it representative.
Use sensitivity before interpretation
Increasing speed should lengthen reaction travel and raise manoeuvre energy; increasing wind or height should increase parachute drift; increasing descent speed should reduce time exposed to wind.
Test these directions before accepting a numerical result. A value with the wrong sensitivity usually signals a misplaced variable, inconsistent unit or misunderstood model. The check is quick and reveals errors that correct-looking arithmetic can hide.
Propagate every geometry change
A new speed, height, reaction time or parachute characteristic can alter contingency width, contingency height and ground buffer.
Those dimensions affect population exposure, containment assumptions and potentially the ground-risk path. Use an assumption register to list every document that consumes the value. Recalculation is incomplete until the map, procedure, risk assessment and credited mitigation all describe the same revised operation.
What this chapter covers
- 01
Flight geography
- 02
Contingency volume
- 03
Ground risk buffer
- 04
Adjacent ground and airspace
- 05
Horizontal and vertical margins
- 06
Parachute deployment and wind drift
Worked example · free
Compute contingency width and height
- 4Add independent horizontal allowances with units.
- 5Derive reaction and climb contributions to height.
- 3State the limits of the engineering result.
Key terms
- Flight Geography
- The volume intended for normal unmanned-aircraft operation.
- Contingency Volume
- The surrounding volume used to manage recoverable abnormal deviation.
- Ground Risk Buffer
- The ground area intended to contain the end of flight after loss of control.
SORA Volumes, Buffers and Safety Distance FAQ
What is the difference between contingency volume and ground risk buffer?
Contingency volume is three-dimensional and supports recovery from abnormal deviation. Ground risk buffer is an area on the ground surrounding that volume and addresses where the aircraft is expected to end flight after loss of control. They represent different states and use different evidence.
Why is vertical reaction gain based on speed?
The taught model assumes the aircraft pitches upward during pilot reaction, so part of forward speed becomes vertical speed. Multiplying that component by reaction time estimates altitude gained before the contingency manoeuvre begins. The assumption must match the aircraft and procedure being credited.
How do I check a safety-distance formula?
Write the physical meaning and unit beside every term. Confirm all terms reduce to distance, check that no uncertainty is counted twice and trace the resulting boundary into the route map, population exposure, contingency procedure and risk classification.
Why record a distance origin?
A value measured from the route centreline differs from one measured outward from another boundary; mixing those origins produces an incorrect operational footprint on the route map.
Exam move
Redraw the nested volumes, then recompute one horizontal margin, one vertical height and one parachute-drift buffer using fresh numbers. Change speed and wind separately and explain every downstream result that must be reopened. Keep a five-column ledger for symbol, unit, physical cause, source and affected documents.
Before checking the arithmetic, predict the direction in which each result should move; reject any output that violates that physical sensitivity. Label every distance origin and state whether it is measured from the route centreline or from another boundary. Beside the drawing, write the trigger and action associated with flight geography, contingency volume, ground buffer and adjacent area.
Finish by walking one changed speed through reaction distance, manoeuvre energy, geometry, population exposure and any dependent risk conclusion. This is the check that keeps a correct formula attached to the operation it describes.
