WINDY FLIGHT CHECKLIST (in metric units) from Greyhawk (and my instructor) during my Drone Operator License Course WALL OF TEXT!!!11!! INTRODUCTIONIt's Greyhawk again! I wanted to share with you these wind flight checks that I obtained during my course in my country. I am sorry that it doesn't cover gusts as it's unpredictable.. Enjoy!
Hello and welcome to WFC. Today’s course will cover the basics of windy flight preparations and prerequisites. Talk no more, let’s get started. I will cover most preparations, dos and don’ts of windy flight and I’ll emphasis two things during the course. That is, don’t underestimate the wind and overestimate your aircraft capabilities. As professionals, there will be a time where you HAVE TO FLY. Not “wanted to”, but “have to”.
Now, let me make this clear. As a trained UAV pilots, you are the most important aspect in determining safe flight and procedures. You’ve been in this course for a week, and I am sure you’ve gotten the basics of map reading, basic flight control and aircraft orientation, ATTI mode, communicating with the Air Traffic Controller and ICAO phonetic alphabets; but the biggest thing remains unexplained. Mother Nature’s most dangerous weapon to all manned and unmanned vehicles and that is the wind. You need to understand, you as a pilot are both DETRIMENTAL, yes, DETRIMENTAL and JUDGEMENTAL to the safe flight and well-being of the others around the A of O. After all, no drone manufacturer will simply take control of your drone and bring it to safety just because “hazardous flying patterns from pilot”. The controller is on your hands. You are the pilot, not the manufacturer. If that was the case, unmanned vehicles are mostly autonomous vehicle that is both controlled by the “manuf” and the pilot that bought it at the first place. This is bad strategy, my dear pilots. None will buy products from that “manuf” because of the fear mongering that this aircraft will “somehow fly around my house without me controlling it”. I hope this little introduction will help you understand a bit why drones and winds don’t mix very well. And why you are important in decision making.
In physics, we know generally that winds affect everything that can move i.e. not fixed to the ground and has a solid rigidity such as an electric pole/utility pole. With that simple knowledge and our life being in cars in various weather conditions, we know that things that can fly and/or light can be pushed away by winds very easily while land vehicles and objects, not so much. These concepts carry forward throughout this course. Trees are solidly fixed by their roots, but their branches are not. This is important in using the old-school method of calculating wind velocity. The Captain had already described it, so I’ll put it aside.
Generally, your surroundings (flying dusts, paper bags, leaves, trees etc.) and you feeling the wind is just a very rough estimate of the wind ABOVE GROUND LEVEL. The horizons, geography and climate do affect the air density above the ground, and sorry, one more thing. Temperature heavily affects air density as well. In simple terms, the geography of your flight region heavily dictates your aircraft’s flight performance; the air density indicates the power needed for an aircraft’s propulsion or motor unit (the motor and propeller as a whole) to maintain stable attitude and to resist winds, if any. Lower surface temperature by climate and/or geography directly relates to higher air density and hence, lower power is needed to maintain attitude and altitude as the air current from the circulating air is transferred to the ambient atmosphere… and I don’t remember what else as I didn’t really pass my Geography test... sorry about that.
Let’s keep it simple. Lower temperatures on ground level indicate higher air density and that allows better flight performance as the motors require less energy to produce the same amount of thrust at a constant altitude. The FAA calls it as the “density altitude”. Now, this is important since we are using the DJI Mavic and Phantom 4. As a rule of thumb, the maximum flight altitude of these UAVs is locked at 500 meters. Flight performance will start to either deteriorate or improve depending on the current surface temperature and at altitudes approx. 200-400 meters from my experience. Since those aircrafts are small when compared to larger commercial aircrafts such as the Boeing 747 or the Airbus A320, flight performance deteriorate at much lower altitudes than of those commercial airliners.
Points to remember or TLDR:
1. Surface wind as felt by the pilot/operator and as shown by the surroundings do not translate very well to winds in the air.
2. Ambient temperature seriously affects air density as much as geography affects flight times and altitude.
3. Low air density = High temperature. 34-40 degrees celsius
4. High air density = Low temperature. 10-25 degrees celsius
5. Flight performance decrease/increase above 200 meters above ground level and the most (poor) at 500m above sea level, wherever you takeoff from e.g. the mountains.
6. Bonus: 1013hPa is the standard atmospheric pressure or FAA’s defined Pressure Altitude.
Although worth mentioning that the DJI Mavic Pro has a maximum flight altitude of 5KM or 5000 meters, this is almost equivalent to a commercial ascending altitude of an aircraft from an airport. At that altitude, stability goes critical and the aircraft may fail. Only the low temperature air density could support such flight altitudes. If you do, please be careful. AND DO take some nice pictures for us, okay?
WINDY FLIGHT – GO/NO-GOThe most important thing here is the dos and don’ts of windy flight. We will use the Wind Flight Polling or WFP. WFP is just a catchy name for the common SOPs used during my windy flight checklist.
Keep this in mind:
- Is the weather bad? Yes/No answer.
- If it’s bad, why are we flying? Mission/Leisure/No Reason
- If Mission, describe it.
- Aircraft chosen.
- Payload if any.
- Do you fly because? I have to/I wanted to/No Reason
- Wind direction and speed (if applicable)?
- Headwind or downwind? Is it possible to fly headwind during the start of mission? Or is the mission objective requires downwind flight?
- Situation Dependent – RTH point, where are we taking off? How far are we going and etc.
- Let’s take a look at one at a time.
- 1. If the weather’s bad, why are we flying it at the first place? As I said, the pilot’s judgment is important in the flight and use of such aircraft in such weathers.
- 2. Do you have to? Or wanted to. Let me put it this way.
a. I have to – I am assigned/contracted to perform a mission that requires the flight of my UAV in such unfavorable weather condition. I have told and forewarned my contractors/superior of my declination due to reasons explained but to no avail. Hence, I am prepared for the worse but I am hoping the best. Should I lose my aircraft due to nature’s acts, I am willing to say that I lost my drone for a good deed, and will try my best to recover the drone but if not, the data that’s critical to the mission. Should I be questioned, my proofs of my contractors’/employers’ hesitation on taking account my valid reasons should suffice; and my attempts on recovering it have failed. b. I wanted to – Just let me fly!!!!
c. No Reason – No Reason.
Examples: - 1. Weather is bad.
- 2. Fly for Mission.
- 3. Search and rescue operation for a missing man.
- 4. DJI Matrice 210 RTK
- 5. Zenmuse XT2 and Zenmuse Z30.
- 6. I have to.
- 7. Northeast, speed approx. 7m/s
- 8. Flight is downwind. Not possible for headwind flight due to last known location.
- 9. Distance is 4 kilometers with a height of 230 meters.
Example 2: - 1. Weather is bad.
- 2. Fly for Leisure.
- 3. lolwut
- 4. Mavic 2 Zoom
- 5. Mavic 2 zoom camera idk whats the real name.
- 6. I wanted to.
- 7. Northeast, speed approx. 23m/s
- 8. Headwind I think idk speed.
- 9. As far as I want haha.
With these information, the pilot will be able to judge safely (if not accurately) on various flight characteristic of the aircraft and adapt accordingly. But, for Example #2, it’s a suicide mission.
WIND CALCULATION Although the captain had made it clear on how to calculate wind, it is very barebone and minimalistic that it may not work everywhere. Hence, you are given a free digital anemometer to assist you in wind speed and direction measurement. Do remember that, Beaufort scale are a rough equivalent to sea wind measurement and don’t directly relate to flight. However it works to give you a visual clue and approximation to actual wind conditions on the ground. The use of anemometer is the same, but only easier and more accurate; it makes no difference on altitude wind readings, only to give you the necessary informations. Let’s get started.
- 1. First of all, the anemometer’s reading must be set to m/s.
- 2. Face the direction of the drone.
- 3. When ready, hold the anemometer in your dominant hand and raise up high as if your name is being called.
- 4. Hold still for 5-10 secs and let go of the measure button.
- 5. Next up, face the drone again. Then, from the direction you are facing with the drone, turn to either left or right.
- 6. Measure the wind speed.
- 7. Take a note pad and write down the wind speed:
a. Facing the drone b. Facing the left/right of the drone.
Wind speed and direction
- 8. The highest wind speed indicates the direction of the wind. However do not take it as a gospel. Use it as a reference.
- 9. The numbers on top/the right is not the direction. It could be from backwards, forwards, left or right.
Remember again, that this is only for ground level. Above ground level, the wind speed will be higher than those on the ground. Do not underestimate the wind and DO NOT overestimate your aircraft capabilities. Anything could happen.
I have to admit that both the Phantom 4 series and Inspire 2 are very powerful wind fighters. Powerful motors, long blades and aerodynamics for the Inspire 2, you may think that they are born to surf the wind. Actually, no. It’s only that either the wind velocity on the air is less than the rated maximum speed of the aircraft AND high wind density or is similar to ground level and you didn’t fly it high enough. Nonetheless, there’s an important calculation here. The ARV and MWS. Aircraft Residual Velocity and Max Wind Speed. ARV is defined as the remaining energy or speed of the vehicle in the air above 250 meters altitude at a constant headwind speed of 5 m/s. From what I heard my instructor, this calculation is inaccurate but to only serve as a rough guide to the drone’s safety on the air. - Let’s take the Mavic for example.
- 1. Ground level = 20 meters.
- 2. Mavic’s MWS = 10m/s
- 3. Wind speed on ground level = 6m/s
- 4. Wind speed at 250m = (6x1.5=9m/s. Always multiply by 1.5! For 100 meters, multiply by 1)
- 5. MWS subtracted by 9m/s = 1m/s
- 6. 10m/s - 9m/s = 1m/s
7. Hence, the ARV is 1m/s and equals to 3.6 km/h usable speed on headwind at 250 meters with a wind speed of 6m/s on the ground and wind speed of 9m/s in the air. 8. This is not in sports mode. I am unable to confirm why.. I presume it to be GPS mode.
This indicates that the aircraft’s rated MWS is mostly taken outdoors at ground level of 15-30 meters and DOES NOT TAKE INTO AFFECT WINDS ON HIGHER ALTITUDES. For 100 meter flights, it’s multiplied by 1. Please do not consider this calculation as perfect. It’s inaccurate and may cause failure. It’s only here for reference only! Air density is also not calculated but it presumes a normal temperature of 34 degrees celsius.
Thank you very much for your time and remember! DO not underestimate the wind and overestimate your aircraft. And finally, rated MWS on DJI aircrafts are not equivalent to performance on high altitudes. I hope you enjoyed!
Some infos maybe wrong. Please chime in and add in your knowledge! It’s a great day to all of you!
Here are the PDF resources for Visual Wind Speed, PDF version of this tip and FAA's Density Attitude.
WINDY FLIGHT CHECKLIST (1).pdf
(739.52 KB, Down times: 4)
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lvl.2
Captain
Second Officer
