Flight Training In Close Proximity of 

Structures, Vegetation, and Power 

Lines

• Pilot and observer procedures

• Anticipated aircraft behavior, updrafts, wind 

shear mechanical turbulence

• Anticipated autopilot behavior, GPS poor 

flight, Semi-Auto, manual

© Alfred A. Gates, 2014 1
Pilot and Observer Procedures

• The observer has equal rolls in producing a safe and 

beneficial flight around structures

• When the plot maneuvers a fixed wing aircraft to a safe 

distance away from the target he will stop and hold 

position by switch to semi-auto or auto and circle a point.

• The pilot should not move from his view point once the 

observer is providing guidance. Also the pilot should only 

be looking at the aircraft and if he must look at the 

controller he should move the controller to his line of sight.

• In close proximity of structures, vegetation and lines, the 

observer will have a better understanding of the position of 

the aircraft using the video monitor. 

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Pilot and Observer Procedures

• During any stage of the 

flight

• The pilot will put the 

transmitter in the field of 

view to check the flight 

status, GPS signal strength, 

battery strength.

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4

 Pilot: Eyes always on the aircraft

 Observer: Advises pilot during every position change

• Operates all camera functions

• Moves around to vide aircraft from different angles

• Uses video feed to advise pilot
Winds/ Weather

• On calm days the winds were stronger than anticipated 

requiring the pilot to manually fly the fixed wing aircraft in 

close proximity to the structures and power lines.

• Biggest limiting factor is weather. Winds greater than 15KTS 

coupled with other factors that create wind require over 

riding the GPS mode.

• Can not fly in rain or snow showers.

• A highly experienced pilot is required.

• The observer has a higher work load than anticipated.

2015 AHS Specialist’ Meeting on 

Unmanned Rotorcraft and Network-Centric 

Operations Program

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Navigation

• It is safer to navigate around wires in Autonomous position 

hold mode provided the autopilot is capable of maintaining 

position in the winds. This allows the pilot time to slowly 

maneuver the aircraft into position. The observer is 

advising the pilot in close proximity of lines and structures.

• The pilot needs to be ready to switch modes if the aircraft 

is blown out of position or if the GPS signal becomes weak.

• The maximum pitch and roll angles are decreased in GPS 

mode when compared with the stabilize and altitude flight 

modes. 

2015 AHS Specialist’ Meeting on 

Unmanned Rotorcraft and Network-Centric 

Operations Program

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Or no wind

This will occur around tree canopies

Shear Zone: This will cause an aircraft to move in pitch and roll to maintain 

attitude control. 

Wind Top Zone: the aircraft can be blown out of view.

FAA Pilots Handbook

2015 AHS Specialist’ Meeting on 

Unmanned Rotorcraft and Network-Centric 

Operations Program

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Still air

Wind

Aircraft can be blown out of view

Wind shear event

2015 AHS Specialist’ Meeting on 

Unmanned Rotorcraft and Network-Centric 

Operations Program

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Anticipating 

• Flight in turbulence (aircraft will move around more)

• Aircraft will be blown in one direction. Pilot is ready 

to switch modes

Wind shear

Video: Wind at top of structure

Aircraft was being blown out of view

Above tree canopy. Pilot had 

seconds to switch modes

2015 AHS Specialist’ Meeting on 

Unmanned Rotorcraft and Network-Centric 

Operations Program

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Terrain turbulence

Mechanical Turbulence

2015 AHS Specialist’ Meeting on 

Unmanned Rotorcraft and Network-Centric 

Operations Program

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Convective Currents
Fixed Wing UAS Flight Modes Commonly 

Uses For Structural Inspection

• Manual: Pilot keeps the aircraft level. Does not hold 

position or altitude (Pilot has the most control 

authority)

• Semi-Auto: keeps the aircraft level and at the current 

altitude if the sticks are released. Does not hold 

position (Change and altitude is limited by the 

maximum/ minimum throttle setting programmed)

• Autonomous: Fly's a preprogrammed pattern. 

Depends on a good GPS signal. 

2015 AHS Specialist’ Meeting on 

Unmanned Rotorcraft and Network-Centric 

Operations Program

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Anticipated autopilot behavior, GPS poor 

flight, semi-autonomous, manual

• The pilot must anticipate that the GPS signal 

strength will decrease. (Be ready to switch 

modes)

• The pilot must anticipate wind shear, updrafts, 

wind gust and wind changes. (Be ready to 

switch modes)

• The pilot must anticipate what the sUAS will 

do in the event of wind shear, updrafts, wind 

gust and wind changes

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Updrafts

• Updraft: Aircraft will climb. Throttle min 

position will not be low enough to maintain 

altitude.

• Pilot response: 

• Let the aircraft climb and wait and see it the 

updraft decays. 

• Switch to manual mode if the aircraft 

continues to climb. Manual mode provides 

more altitude and atitude control authority

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Wind Shear

• Wind Shear: Aircraft will pitch and roll and 

possibly move away from the pattern flight. 

• Pilot response: 

• If a structure is close switch to Semi-Auto 

mode or manual. If there is no structure close 

by. Let the aircraft move around and fly the 

aircraft through the wind shear zone.

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Wind Gust, Wind Increase

• Wind Shear: Aircraft will blown in one direction. 

• Pilot response: 

• If structure is close or if the aircraft is being blown 

out of view switch to manual mode. 

• If there is no structure close by. Let the aircraft 

move around and see if the wind gust will died 

down

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GPS Signal Strength Reduction or 

Signal Loss

• When the GPS signal becomes weak. The 

aircraft will chase a unknown GPS position at 

the maximum pitch and roll positions. The 

aircraft will maintain altitude.

• The pilot must immediately switch modes to a 

none GPS mode, Semi-Auto or Manual.

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