SUAS Crash Investigation

If you don’t figure out why your 

unmanned aircraft crashed then you 

will crash it the same way in the 

future.

© Alfred A. Gates, 2014

1
Crash Investigation Tools

• Flight data recording 

– Video camera recording from flight

– On board SD card

– Recording through a ground control station link

• Weather

• Pilot control observations

• Observer observations

• Crash site

• Internet search on make model common crash's

© Alfred A. Gates, 2014 2
Crash Investigation

• Pilot: Did the aircraft operate as expected

• Observer: What happened prior to crash and 

what is the camera doing

• Weather: What are the winds and is it raining 

or snowing

© Alfred A. Gates, 2014 3
Crash Investigation, Aircraft Behavior 

Prior to Crash What to Look For

• Rapid spinning (YAW) and pitch or roll in one direction: Loss 

of power to one or more arms. (Prop, ESC or Motor failure)

• Controlled roll and or pitch in one direction and controlled 

flight by AP in that direction: GPS signal loss

• Slowly or quickly losing altitude: Battery low, loss of power

• Increasing pitch and or roll oscillations of aircraft: Autopilot 

tuning problem.

• Uncontrolled pitch and or roll and YAW, loss of attitude:

• Typically the aircraft will pitch and or roll to an angle and 

maintain the angle. The angle will be steep and the aircraft 

will dive External or onboard electromagnetic interference, 

autopilot problems.

© Alfred A. Gates, 2014 4
Inflight Observations

© Alfred A. Gates, 2014 5

Dropping slowly 

or quickly

Loss of power

Rapidly spinning 

out of control

Failure of 

propeller ESC, 

motor or 

connection

Sharp angle 

and flight in a 

direction

GPS signal loss

Rapid increasing 

oscillation

Autopilot tuning 

problem

Observation and possible cause

Aircraft YAWs and rolls 

and attitude is lost: 

Electromagnetic 

interference, autopilot 

problems
Crash Site Investigation

• Debris field

– Wreckage in one location

• Human error, autopilot or electronics failure

– Wreckage spread over a large area

• Break up in flight inspect parts to determine point of 

failure

– Aircraft in one location with a missing component

• Missing component has something to do with the 

failure

© Alfred A. Gates, 2014 6
Aircraft Investigation, Crash Site

• Do not pick up the aircraft (Batteries may be 

connected and burning)

• Take pictures

• Locate: All propellers, motors and ESC

• Check: Propellers are they tight, motors lose 

or tight, are ESC plugged into the autopilot 

and motors, is the autopilot loose, is the 

battery connected

© Alfred A. Gates, 2014 7
Aircraft Crash Investigation

• Difficult to separate the actual crash from the cause

• Are props hubs tightly bolted on the motors

– (Props can be broken but the hubs should be tightly mounted)

• Are the motors securely mounted to the arms

– (Motors must be bolted down tightly)

• Dose the ESC look burnt or do they smell

– (They could burn out after impact)

• If the aircraft is intact are the ESC wires plugged in to the 

AP

• Is the battery pack damage is it plugged in

• If the arm are bolted on are the bolts tight

• Is the autopilot loose

© Alfred A. Gates, 2014 8
Internet, 3DR IRUS Crash Problems 

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Autopilot Failure

Inflight Observation: Steep bank and Yaw

Ground Observation: Wreckage at one location

What failed: Loss of Attitude Control

Cause: Electromagnetic Interference

Video: See directory 

© Alfred A. Gates, 2014

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Autopilot Failure

Inflight Observation: Steep bank and Yaw

Ground Observation: Wreckage at one location

What failed: Loss of Attitude Control

Cause: Electromagnetic Interference Internal

Video: See directory 

© Alfred A. Gates, 2014

13
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Structural Failure

Inflight Observation: Aircraft spinning and loss of control

Ground Observation: Wreckage at one location except for 1⁄2 of a propeller

What failed: Propeller break up in flight

Cause: Flight with a damage or poorly manufactured propeller

Video: https://www.youtube.com/watch?v=m7KiJgMU75Y

Note: The aircraft will do the same thing with a ESC 

failure, motor failure, include a wiring 

disconnection

Replace all propellers with higher strength 

propellers. Replace propellers over time due to UV 

damage

Preflight: Check for damaged propellers

Check tightly fitting propellers

Check security of motor mounts

Check ESC wire connections © Alfred A. Gates, 2014

15
GPS Signal Loss

Inflight Observation: Aircraft will bank in a direction 

can continue to fly in that direction (typically)

Ground Observation: Wreckage at one location 

What failed: Loss of GPS signal

Cause: Flight around structure that blocked the GPS 

signal, poorly trained pilot

Video: https://www.youtube.com/watch?v=G8jPO_mXWDw

Clamed GPS signal loss

Video: https://www.youtube.com/watch?v=_U8iHn_2l0U

Looks like LTR mode GPS loss and switched in ATT model 

and was unable to fly the aircraft

Pilot requires training

© Alfred A. Gates, 2014 16
Unexplained Loss of Control

Inflight Observation: Aircraft will bank and YAW in a 

direction or start to oscillate in pitch or roll 

Ground Observation: Wreckage at one location 

What failed: On board electromagnetic interference or 

autopilot tuning???

Cause: Location of onboard electronics or tuning of aircraft

Video: https://www.youtube.com/watch?v=OZkMxGgz8b8

Several similar crashes

Auto pilot tuning problem

Determine cause: Through internet search and 

testing of components.

If you don’t figure out why your unmanned aircraft 

crashed then you will crash it the same way in the 

future.

© Alfred A. Gates, 2014 17
After A Crash 

• Determine the cause

• Disassemble aircraft and inspect components

• Replace parts and assemble

• Bench test

• Flight test all modes all maneuvers

• Ready for service

• DO NOT FLY AIRCRAFT UNTILL THE CAUSE 

HAS BEEN IDENTIFIED

© Alfred A. Gates, 2014 18