Operational Procedures

   

Pre-flight Checks

 

In addition to understanding the factors that impact the safety of flying a UAS, you should conduct pre-flight checks to help prevent drone accidents. These checks are required by the FAA before every flight. Checklists are regarded as a foundation of standardization and safety in the aviation industry.  Improper use or non-use of checklists is often cited as a major contributing factor to aircraft accidents.

While the FAA does not require UAS Pilots to draft a pre-flight checklist, having one for your specific drone model is highly recommended. Aviation checklists should be considered living documents, and they should be changed whenever aircraft modification or significant changes in operations occur. These checklists should be reviewed annually at a minimum.  

Pre-flight checks should be performed before every operation, and most pilots perform post-flight checks to assess and fix potential damage before the next operation. If any part of the pre-flight inspection fails, drone operation is not safe.

You can reference this Drone Park example checklist Download Drone Park example checklist for help making your own pre-flight checklist. Remember, you should use your own pre-flight checklist created for your specific drone and operation. 

Before flying, always consider these factors:

  • Weather
  • Airspace restrictions
  • Temporary flight restrictions
  • Drone condition (battery, maintenance)
  • Hazards in the air and on the ground

 

Other Factors

Below are some other challenges and hazards you may encounter while flying a drone. 

Consideration

Description

Perception

The ability to gather and interpret sensory information.

  • Detection of Sensation or a Stimulus
  • Pattern recognition
  • Interpretation
  • Situational Awareness

When flying drones, objects may appear closer or farther away than you think which causes many piloting errors.

Depth perception makes it possible for the eyes to determine distances between objects and to tell if something is near to us or far away.

Voltage

Most drones use Lithium Polymer (LiPo) batteries which must maintain certain voltages to be useful. Many factors such as age of the battery and operating conditions can determine how much voltage you will get out of a battery and thus how long you will stay in the air.

As you can see in the graph, a hot, cold, or aged battery will discharge voltage more quickly. Operating conditions such as high winds will likely also adversely affect the amount of flight time from a battery. 

Image of battery voltage over time during a flight. Shows the quick drop that occurs near the end of the battery life. This explains why one needs a battery failsafe.

 

Radio Interference

Drones communicate to the pilot during flight via radio waves. Many things from power lines to other drone operators can cause interference. In simple cases, this can cause temporary loss of control or visual sight and in more drastic cases fly away.

  • Be aware of radios on same frequency
  • Be aware of powerful radios nearby (on different frequencies too)
    • *Microwave and Satellite Trucks
  • Ensure antennae have good electrical connections and are isolated electrically from other systems
  • Shield RF noise generating components (cheap switching power supplies)

RF Line of Sight

Any object between the receiver and transmitter can reduce or entirely block the signal (poles, people, tables, cars, etc.)

Frequency dependency

  • Low frequencies can pass more easily through objects
    • 2.4GHz can go through sparse tree cover and some objects
  • High frequencies have difficulty passing through objects
    • 5.8GHz has great difficulty in passing through trees

Wind Factors

Wind direction and speed can significantly impact endurance and should be considered when flight planning. Mechanical turbulence caused by terrain and structures can impact small UAS.

On Rotorcraft - Drones should be launched downwind of the pilot so that when the aircraft naturally drifts you can recover it more effectively.

Wind Factor

On Range -  

Wind impacts while flying downwind and into the wind. 

Land-Water Interactions

During the day, air over land heats up which causes it to rise. Then at night it cools and condenses. This causes disruptions in pressure that may affect your drone's flight performance. 

Image describing land-water interactions.

Altimeter Indicators

If your drone tells you what its altitude is, most likely the number is measured from where you lifted off. This is important to note because if you take off in a location with variable terrain your drone's actual altitude above the ground may be different than what is shown on your control station.

Image describing the impact of altitude on horizontal motions.

Battery Failsafes

The Pilot must understand the behavior of and approximate time to reach failsafe. They also must plan adequate battery reserve to return to a landing location

  • The PIC should be able to set specific battery failsafes for their drone. Generally they are: 
    • Return to Home
    • Descend and Land
    • Hover in Place
  • A very low battery may not be able to deliver enough power to produce required thrust
  • A very low battery can be permanently damaged

Scan Techniques

 

  • Like an instrument scan pattern in airplanes – continuous pattern of your aircraft and instrumentation
  • Don’t stare for long periods – use off-center viewing
  • Use peripheral vision
  • Listen for traffic – terrestrial and aerial

Image showing the scan techniques one should use during UAS flight.