Module 1/5 · Weeks 1–3 · 27 h

Mission planning

DRT 342 Mission Planning, Autonomous Operations and Beyond Visual Line of Sight

About 90 minDraft, awaiting reviewLast updated 26 September 2026

By the end of this module you will be able to

Explain the mission planning and execution cycle from brief to debrief
Define the operational area using flight geography, contingency volume and ground risk buffer
Select aircraft and payload from the mission question
Lay out a survey pattern from ground sampling distance and image overlap
Calculate flight time in wind and an energy budget with a reserve

Prerequisites: DRT 341 modules 1–4 · Vectors and trigonometry (DRT 111)

Why this matters

Many drone accidents are not caused by a broken aircraft but by a plan that was not good enough: nobody knew the wind would pick up in the afternoon, nobody budgeted energy for the way back, or nobody noticed a road running under the flight path. Mission planning is therefore a core skill of the professional UAS operator. The more automated the mission, and the further it goes beyond visual line of sight, the harder it is to fix a planning error in the air, because a person is no longer in the control loop every second.

A simple comparison: planning a mission is like planning a long road trip. You need to know why you are going, which route to take, whether you have enough fuel, where you would stop if the car broke down, and who needs to know you are on the road.

This module builds on knowledge units from the drone knowledge hub: writing a brief, assessing a site, integrating weather into the plan, and the mission-concept exercise. Read them before class.

The mission cycle

A good mission does not start with opening a waypoint editor. It starts with the question that needs an answer.

A six-step cycle: brief with question and output, site and weather assessment, route energy and contingency plan, decide GO HOLD or NO-GO, fly and monitor, then debrief and lessons learned feeding the next brief — Figure 1 The mission planning and execution cycle

Brief: state the question, who receives the result, how long the result stays useful, and the team roles. “Imagery no coarser than 3 cm per pixel of a 2 km canal, delivered to the municipality within 48 hours” is far better than “take the clearest possible photos of the canal”.
Assess the site and weather: obstacles, people, roads, airspace, launch and alternate landing sites, forecasts and observations. Keep “what has been checked” separate from “what is still an assumption”.
Plan the route, altitude, speed, energy, and the procedures for abnormal events.
Decide: GO when conditions are met, HOLD when key information is still unconfirmed, NO-GO when risk exceeds the criteria.
Fly and monitor, comparing actual state with the plan throughout.
Debrief: record what differed from the plan and feed the lessons into the next mission.

CAAT publishes an Operations Manual (OM) template, CAAT-GM-UAS-001, which has separate sections on responsibilities, planning, site survey and communication. Each operator writes its own procedures in its OM for its aircraft and type of work. The tables in this lesson are exercises only, not a mandatory regulator format.

The operational area

A map with a single flight line is not enough, because a real drone never flies exactly on the line. JARUS SORA 2.5 divides the area into layers, a concept that is useful even for missions that do not use SORA.

Cross-section: the flight geography is the innermost box containing the flight path, surrounded by the contingency volume, with the adjacent area outside. On the ground beneath is the ground risk buffer. Operational volume equals flight geography plus contingency volume — Figure 2 Layers of the operational area in the SORA concept

Layer	Meaning	Example of how it is set
Flight geography	The area and heights where the aircraft flies in normal operation	A 200 m wide canal corridor up to the authorised height
Contingency volume	The surrounding volume used in abnormal situations, where contingency procedures return the aircraft to the flight geography	Allows for position error, wind drift and stopping distance
Ground risk buffer	Ground area around the operational volume where the aircraft is expected to end its flight if control is lost	SORA 2.5 proposes a 1-to-1 principle, as wide as the flight height, as a starting value
Adjacent area	The area further out, assessed for who would be affected if the aircraft escaped	A community or main road next to the work site

SORA 2.5 states that the operational volume must account for navigation accuracy, flight technical error, path definition (map) error and latencies. It is not drawn by feel.

Selecting the aircraft and payload

Choose from the mission question, not from whatever aircraft is in the store room (review DRT 341 modules 2 and 4).

Mission question	Resulting requirement	Suitable choice
Map a 48 ha farm	Wide area, long straight lines	Fixed-wing or VTOL with an RGB or multispectral camera
Inspect cracks under a bridge	Hover close to a structure; GNSS may be blocked	Multirotor with a zoom camera and collision protection
Search for a missing person at night	See heat, stream live video	Multirotor or VTOL with a thermal camera and video link
Inspect a 30 km pipeline	Long range beyond visual line of sight	Fixed-wing or VTOL with long-range C2 (modules 3–4)

Routes and waypoints

An automated mission is a list of waypoints, each with coordinates, altitude and a command (module 2). Common route patterns are:

Point to point for delivery or transit to the work area
Lawnmower survey for mapping
Orbit around an object for 3D capture
Linear following of a structure such as a power line or pipeline

Image resolution and survey lines

The ground sampling distance (GSD), the ground size of one pixel, depends on flight height $H$ , sensor pixel size $p$ and focal length $f$ :

GSD = \frac{H \cdot p}{f}

Adjacent images must overlap so that software can stitch them. If the image footprint width on the ground is $W$ and the side overlap is $o_{side}$ , the line spacing is $s = (1 - o_{side}) W$ . The photogrammetry is covered in the mapping courses.

Top view: eight back-and-forth survey lines cover a rectangle, with overlapping image strips. Line spacing equals one minus the overlap times the ground footprint width — Figure 3 Lawnmower survey pattern and image overlap

Example 1 Laying out survey lines

A camera has a 13.2 mm wide sensor, images 5472 pixels wide and an 8.8 mm lens. It flies at 80 m with 70% side overlap over an area 540 m wide and 800 m long at 10 m/s.

Pixel size $p = 13.2/5472 = 0.002412$ mm $= 2.412 μ m$
$GSD = \frac{80 \times 2.412 \times 1 0 ^{- 6}}{8.8 \times 1 0 ^{- 3}} = 0.0219$ m $\approx 2.2$ cm per pixel
Footprint width $W = 5472 \times 0.0219 \approx 120$ m
Line spacing $s = (1 - 0.7) \times 120 = 36$ m
Number of lines $= 540/36 + 1 = 16$ ; total path $16 \times 800 + 15 \times 36 = 13340$ m
Flight time $13 340/10 = 1334$ s $\approx 22.2$ minutes, excluding take-off and landing

A 3 cm GSD would allow flying up to about 109 m, but the general conditions of Thailand’s 2015 Ministry of Transport notification prohibit flying higher than 90 m above ground; anything higher needs specific authorisation. The calculation is only a technical upper bound.

Energy and wind

Wind changes flight time

Ground velocity is the vector sum of air velocity and wind, $v_{ground} = v_{air} + w$ . The time for each leg is its distance divided by its ground speed:

t = i \sum \frac{d _{i}}{v _{ground, i}}

Example 2 Does a tailwind cancel a headwind?

A drone flies at 12 m/s airspeed to a point 2 km away and back, with a 4 m/s headwind on the way out.

Outbound $v = 12 - 4 = 8$ m/s, time $2000/8 = 250$ s
Return $v = 12 + 4 = 16$ m/s, time $2000/16 = 125$ s
Total 375 s, compared with $4000/12 \approx 333$ s in calm air

Wind adds about 12.5% even though there is both a headwind and a tailwind, because more time is spent in the headwind. A multirotor draws nearly constant power over time, so the energy used rises too.

Energy budget

The usable energy is not the energy on the label. Remove the share that should not be used (usable fraction $η$ ) and divide by average power $P$ :

t = \frac{η E}{P}

Operators set a minimum reserve in their OM, for example landing with no less than a stated percentage of energy. This course uses an example policy of “use 80% of battery energy”. Real values must come from the manufacturer and the OM.

Example 3 Can this mission be flown in one sortie?

Use the mission from Example 1. The battery is 22.2 V, 8.0 Ah; average survey power is 350 W; take-off and landing take 2 minutes in total.

Energy $E = 22.2 \times 8.0 = 177.6$ Wh; usable $0.8 \times 177.6 = 142.1$ Wh
Available flight time $142.1/350 = 0.406$ h $\approx 24.4$ minutes
Required time $22.2 + 2 = 24.2$ minutes

Only 0.2 minutes of margin remain, with no allowance for wind, climbing or holding. The mission should be split into two sorties, for example lines 1–8 and 9–16, with the battery change built into the plan.

Class activity

Activity: Build a mission concept pack

Use worksheet B01 from the drone knowledge hub (a hypothetical 2 km canal survey).

Write a one-page brief with the question, recipient, timing and team roles.
Sketch the flight geography, contingency volume and ground risk buffer on the practice map, with reasons for each distance.
Calculate GSD, line spacing and flight time, then check the energy budget with values given by the instructor.
Build an assumption register listing what still needs checking, the data owner, and the conditions that would trigger HOLD.

The pack is an exercise, not an authorised flight plan.

Common mistakes

Watch out

Starting by drawing the route before writing the question and deliverable
Making the flight area exactly as wide as the route, with no contingency volume or ground risk buffer
Assuming a tailwind on the way back cancels the headwind on the way out
Using the full label energy without a reserve
Treating an old map image as the state on the day: no people in the image does not mean no people on the day

Summary

The mission cycle is brief → site and weather assessment → plan → decide → fly and monitor → debrief
In the SORA concept the operational area consists of flight geography, contingency volume and ground risk buffer
Choose aircraft and payload from the mission question
GSD $= H p / f$ and line spacing $s = (1 - o_{side}) W$
Wind always lengthens an out-and-back flight; the energy budget must keep the reserve set in the OM

Check your understanding

Why is a brief that says “take the clearest possible photos” not enough for planning?
How does the contingency volume differ from the flight geography?
Flying at 60 m with a 2.412 µm pixel and an 8.8 mm lens, what is the GSD?
With a 100 m ground footprint and 75% side overlap, what is the line spacing?
At 10 m/s airspeed, out and back over 1.5 km with a 5 m/s headwind on the way out, what is the total time compared with calm air?

Answers

It does not say what the imagery is for, what resolution is needed, who receives it or when, so the team cannot choose height, equipment or acceptance criteria.
The flight geography is where the aircraft flies in normal operation. The contingency volume surrounds it for abnormal situations, where contingency procedures bring the aircraft back to normal.
$GSD = 60 \times 2.412 \times 1 0^{- 6} /8.8 \times 1 0^{- 3} \approx 0.0164$ m, about 1.6 cm
$s = (1 - 0.75) \times 100 = 25$ m
Out $1500/5 = 300$ s, back $1500/15 = 100$ s, total 400 s against 300 s in calm air (33% longer)

Key formulas

Ground velocity	$v_{ground} = v_{air} + w$
Total time over several legs	$t = \sum_{i} \frac{d _{i}}{v _{ground, i}}$
Ground sampling distance (GSD)	$GSD = \frac{H \cdot p}{f}$
Survey line spacing	$s = (1 - o_{side}) W$
Flight time from energy	$t = \frac{η E}{P}$

Key references

Joint Authorities for Rulemaking on Unmanned Systems. (2024). JARUS guidelines on Specific Operations Risk Assessment (SORA), main body, edition 2.5 (JAR-DEL-SRM-SORA-MB-2.5). link
สำนักงานการบินพลเรือนแห่งประเทศไทย. (2565). รูปแบบคู่มือปฏิบัติการบินของอากาศยานซึ่งไม่มีนักบิน (CAAT-GM-UAS-001, Issue 01 Rev 00). link
International Organization for Standardization. (2023). Unmanned aircraft systems – Part 3: Operational procedures (ISO 21384-3:2023). link
Fahlstrom, P. G., Gleason, T. J., & Sadraey, M. H. (2022). Introduction to UAV systems (5th ed.). Wiley.
Wolf, P. R., Dewitt, B. A., & Wilkinson, B. E. (2014). Elements of photogrammetry with applications in GIS (4th ed.). McGraw-Hill.
สำนักงานการบินพลเรือนแห่งประเทศไทย. (2569). ประกาศ กพท. เรื่อง หลักเกณฑ์และวิธีการในการอนุญาตให้ผู้บังคับหรือปล่อยอากาศยานซึ่งไม่มีนักบิน ประเภทอากาศยานที่ควบคุมการบินจากภายนอก ที่มีน้ำหนักไม่เกิน 25 กิโลกรัม ปฏิบัติแตกต่างไปจากเงื่อนไขที่กำหนด พ.ศ. 2569 (มีผล 17 พฤษภาคม 2569). link
กระทรวงคมนาคม. (2558). ประกาศกระทรวงคมนาคม เรื่อง หลักเกณฑ์การขออนุญาตและเงื่อนไขในการบังคับหรือปล่อยอากาศยานซึ่งไม่มีนักบิน ประเภทอากาศยานที่ควบคุมการบินจากภายนอก พ.ศ. 2558. ราชกิจจานุเบกษา, 132(86 ง), 6–12. link

In class / field

Lecture, case discussion and in-class problem solving

Learning evidence: Quiz results and submitted exercises

Module quiz

This is a formative self-check, not a graded exam

Knowledge domain: Mission planning, flight and simulation · Law, safety and risk

Mission planning

By the end of this module you will be able to

Why this matters

The mission cycle

The operational area

Selecting the aircraft and payload

Routes and waypoints

Image resolution and survey lines

Energy and wind

Wind changes flight time

Energy budget

Class activity

Common mistakes

Summary

Check your understanding

Key formulas

Key references

Further reading

Defining the mission concept

Integrating weather into the mission plan

Brief: questions, deliverables and team roles

Site assessment and go/no-go decisions

In class / field

Module quiz

Mission planning

Lesson

By the end of this module you will be able to

Why this matters

The mission cycle

The operational area

Selecting the aircraft and payload

Routes and waypoints

Image resolution and survey lines

Energy and wind

Wind changes flight time

Energy budget

Class activity

Common mistakes

Summary

Check your understanding

Key formulas

Key references

Further reading

Defining the mission concept

Integrating weather into the mission plan

Brief: questions, deliverables and team roles

Site assessment and go/no-go decisions

In class / field

Module quiz