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The number one reason for Phantom crashes (a little surprising)

Discussion in 'General Discussion' started by Jussaguy, Feb 14, 2016.

  1. Jussaguy

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    This is from DJI themselves.

    Quite awesomely one of the techs at DJI listed the top ten reasons for their currently thousands of RMAS a month and guess what the #1 reason for RMAS is? It's not "fly aways", crashes, or anything else you might guess unless you guessed unintentional CSC motor kills.

    I understand that the 2 seconds to kill the motors by putting the sticks on either of the lower corners sounds like a strange move to do but if you happen to be flying your Phantom with some fpv like moves or you are used to flying racing drones, it's not such a crazy move.

    Or let's say you're descending and you happen to accidentally move the stick a little left or right and you at the same time start strafing left or right, it would not be too difficult to do the same on that side. Well in a couple nano seconds, your motors off bird is making a bee line to the ground.

    Tip: it is possible to restart your motors during free fall but unless you are above 250 meters and do it right away, no chance of saving and even if you manage it, you need some luck based on how it's flying. The move is restart motor and IMEEDIATELY ascend up (no thottle forward). Test it in the sim.

    I totally understand the need for a CSC fail safe should your bird go rogue and is heading towards a ton of people but if it's the number one RMA, it's obviously too easy to accidentally do. I do fly fpvs so my OCD has me constantly thinking to not accidently CSC and I never have but could totally understand if someone accidentally did and since it's by DJIs own admission the number one reason for RMAs, the solution to cut back on their RMAS is to fix this.

    Real simple. Add one level of complexity to force a crash.

    For example, those same stick movements but also having to press either one of the assignable bottom buttons. C1 and/or C2.

    Proof is in the pudding. It's their main reason for crashing so they are probably putting more people at accidental risk then they are saving by having such an easy CSC. Never mind that they will seriously cut down on RMAs freeing up more time got R&D :)

    Do you guys agree?
     
  2. msinger

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    FYI, that list is not in order.
     
  3. Jussaguy

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    Here is their list btw. They list all of these as pilot error, but IMHO, the number one reason is a design flaw on ease of CSC.

    Last edited by DJI-Tim In 2016-1-22 13:33 Editor
    TOP 10 common pilot errors

    [​IMG]
    final.jpg (182.86 KB, Down times: 36)

    Download attach

    2015-11-18 20:27 Uplaod


    We found out many RMA cases we have worked on in DJI was caused by pilot’s error
    Analyzing the flight data or so called black-boxes we listed top 10 as below:


    1. CSC in the mid-air (Combination Stick Command)
    The newbies favorite way to crash the drone by pulling the sticks to the down inner corners \ / or outside corners / \ and stop the motors
    Solution: Never do this movements on a sticks while in the mid-air, unless in case of emergency

    2. Propeller shoots off
    Of course the self-tightening props is a great invention of humanity, but some of the users only slightly push it till it stops to turn and think that it’s enough, which brings aircraft to shoot the props off on a high RPM
    Solution: Never let the propellers loose on a motor. No matter if you are using self-tightening props or quick release props, always make sure that every propeller sits tight on a motor before taking off.

    3. RTH Crash
    You shooting the beautiful building (tree, hill, tower etc.), and flying behind it for the better shot, suddenly you lose the RC signal, because the building got on the way between the aircraft and the remote controller. So automatic go-home function turns on and your aircraft crashes into that building on a way back home.
    Solution: Set your return to home altitude higher than any obstacles (trees, buildings etc.) in your area.
    MC settings> Advanced Settings> Failsafe mode

    4. Auto landing far from home
    Once your aircraft is out power, you will get low battery warning and 10 seconds to cancel the RTH. After canceling the RTH you still can keep flying, but once your battery will hit the critical battery level, aircraft will start auto-landing. Pilot cannot cancel the landing, but the roll, pitch and yaw are still controllable. That’s a good luck if it lands on an opened spot, but if there is a trees or water… you know…
    Solution: Go back home straight after low battery warning, don’t force your drone to fly till it’s totally out of power.

    5. Flying out of sight
    Flying out of sight is pretty dangerous, because all you can see is the video from the aircraft, which limits your view of the environment and can bring pilot to the altitude or direction misjudgment. Also it raises the chances to crash into the objects hard to see through the FPV, such as power lines.
    Solution: Do not fly out of the sight if you are not familiar with flight environment.

    6. Watching FPV and flying backwards
    Everyone likes to do some beautiful shoots like this, but flying backwards we don’t see the way aircraft is moving to, so it’s extremely easy to crash your drone into the other objects on the way. It’s like walking backwards without watching the way.
    Solution: Do not stare at the screen all the time, watch your aircraft and flight environment.

    7. Indoor flight
    Very often flying indoors due to the low GPS signal aircraft can drift, so it is getting difficult for the non-experienced pilot to control it.
    Solution: Exercise your ATTI mode flight skills outside, to get the proper feeling of how to fly the aircraft without GPS

    8. Failsafe and gain the altitude
    As all we know, when the aircraft is out of the 20 meters radius from home point in case of low battery level, it will ascend to the failsafe RTH altitude and then go home. So some of the pilots are getting the low battery warning and go land their aircraft manually without canceling RTH. But since the aircraft is out of the 20m radius from thehome point, at that very moment before drone touches the ground it lifts up automatically to the failsafe RTH height, and flies to the home point. This makes a lot of pilots’ panic, so some of them start to do some odd stuff like CSC, and eventually crash their drones.
    Also, aircraft can hit the obstacle above it, such as (tree branches, roofs etc.) while automatically raising up.
    Solution: 1. Keep calm, your aircraft is not flying away
    2. Land close to the home point
    3. Cancel the low battery RTH andland manually.

    9. Bad environment
    Well, the bad environment is a reason of the huge part of the crashes.
    What is bad environment? Metropolis full of skyscrapers or any surrounding of the high buildings, Power stations,TV stations, Mobile towers, high voltage lines, any sources of signal or electromagnetic interference.
    Solution: Fly in an opened space, far from the buildings, power line towers and all those places described above.

    10. Braking distance
    Flying aircraft at the full speed is a great feeling, but sometimes you can meet obstacles on a way, that you can crash in just because it’s too late to brake.
    Solution: Same as a car, aircraft has its own braking distance, so keep it in mind. It’s better to start soft braking earlier than make an emergency stop with a risk of crash.

    Be aware and fly safe!
     
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  4. Jussaguy

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    It's not?

    It says top ten reasons and then lists number 1. Seems to me that the order is the order but if that's not true, how do you know this?

    I spoke to Tim at DJI about this issue after they posted the list. He didn't say otherwise. You might be right but why so you say that?
     
  5. msinger

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    Tim (the OP) did not confirm, but Dave doubts it here. I'm assuming he has an inside scoop on this information since he works for DJI.
     
  6. Meta4

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    No ... it's not in order.
    Accidental CSC is quite rare.
    The incidence reported on the three forums I watch would be less than one per month and most are the result of:
    1. Not reading the manual &
    2. Jerking the sticks like a crazy chimp
    It just isn't something that happens in normal flight.

    If you want to know what really causes Phantom crashes, look at flying close to trees, buildings and other obstacles, bad compass calibration, disorientation and not knowing how to use the aids in the app and not understanding RTH.
    These would all be reported multiple times each week.
     
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  7. Jussaguy

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    Yes, I read that thread and he "doubts" that its the number one reason but it sure read that way.

    You said it like it was a fact though and I spoke to a friend rep at DJI the other day and he agreed that he didn't think it was number one but said it could be.

    It's doesn't really matter though. That's its even in the top ten is reason enough for me to validate what I always thought: That the CSC is way too easy on DJI Inspire and Phantom IMO.
     
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  8. msinger

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    Who is Chip?
     
  9. Jussaguy

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    Of course and in the OP of this thread I said that that is what you would think naturally but by Tim's list it sure seems that that is the #1 reason but if its in the top 10 by DJI's admission, it's not "quite rare" I wouldn't think.

    I also agree that it takes a careless use of the Phantom or whichever to accidentally go to that motion but again if you fly FPVs, this is not a crazy move so I could see someone accidentally doing it.

    It's an easy fix, just make a button added to the stick movement. Why would anyone disagree with that? The first person that crashes a bird by this method on accident will agree.
     
  10. Jussaguy

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    I actually edited that. Chip is someone at a vendor I was speaking to about this. I did speak to someone at DJI who I will leave unnamed who actually said it's not the number one reason but the person from DJI that I spoke with said they have got plenty requests to make the CSC just a little more difficult.
     
  11. msinger

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    Hmm. Got it. I am thoroughly confused now though.
     
  12. Meta4

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    There should be enough in this thread already for you to realise that it is not the number one cause of crashes.
    The DJI forum is probably the last place to go for accurate information and a lot of things there are misleading or wrong.
    And as I said ... Despite the exaggerated fears of new flyers, accidental CSC is very rare.
     
  13. Jussaguy

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    I respect your opinion but a couple things that don't fly with that thought.

    Firstly, I agree that DJI forums is not the best place in general to get info about things from users but it is definitely the best place to get info from the techs.

    Secondly, I've never crashed a drone (other than a toy drone) and I have a fleet of them (the Phantom being my favorite and yes I have the Inspire), and I am CONSTANTLY thinking about not doing an accidental CSC so at the very least I represent one person that is a very careful flier. I calibrate compass on every FLIGHT, not day, I calibrate IMU every few days and take most precautions that are available to us but I am also admittedly riddled with OCD so I am thinking about not doing an accidental CSC all the time.

    It's certainly possible, even likely that it's not the number one reason and I was frankly quite surprised to see it was (or at least that I read it that way) but I still think that just adding a button push would make it almost impossible to do it accidental and that could not only theoretically save a bird or two but a life.

    It's in Tim's top 10. That to me is an easy firmware fix to get rid of one of the top 10 whether it's first or last. Am I wrong?

    So it's not an exaggerated fear of a new flyer. I have been flying before it was en vogue as a hobbyist FPV RC flier and then when my hobby mingled with my career, life was great so I my exaggerated fear is only in my OCD but I am not the only one. Besides, exaggerated fears by new flyers are also a reason to make it more difficult to do a CSC.

    I'm not understanding how anyone disagrees. The reason for CSC is to send a bird down in an emergency and it's just as quick for me to bring the sticks together and hit c1 or c2 along with it and it eliminated any worry by new scared flyers or advanced long term flyers with OCD. :)

    I like analogies: Has anyone ever accidentally hit the gas instead of the breaks in your car or vice versa? Imagine if doing so made your car fall 500 feet. Would you want them to make it so that fall would have to happen while hitting the wrong thing while hitting a button simultaneously at least?

    This is the difference between pilots and drone fliers. No offense to the name of this forum (which is a great forum) but to me, if you want to be called a pilot, you have to go down with the ship if it crashes. I bet everyone would agree with me if they were inside of their bird. Lol. Tongue and cheek everyone FTR.
     
    #13 Jussaguy, Feb 14, 2016
    Last edited by a moderator: Feb 14, 2016
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  14. ObiDon

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    I think the CSC in the mid-air (Combination Stick Command) should be fixed. It should have a fail safe button that needs to be pressed on the screen to initiate. Being able to have your aircraft drop out of the sky is never a good idea IMHO.
     
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  15. Jussaguy

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    It doesn't even need to be on screen and I love when people agree but I think you are right but they shouldn't remove the controller CSC altogether because what happens if the issue is with the app and you had to kill it? I think you are right that the app should have a button with a slider. The reason for the sliders on landing and stuff like that is in case your screen freaks out and starts pressing buttons on its own, it's unlikely to get a swipe.

    Either way, again, just added the c1 or c2 button and bam, fixed and nobody would care and nobody would accidentally crash their bird by descending and banking or accidentally drifting the stick.

    But thanks for agreeing! ;) I love allies. Ha.
     
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  16. msinger

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    I agree too, but I would prefer to see a method that works on all remote controllers. Not all of them have a C1 and C2 button right now.
     
  17. Meta4

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    That rings a big alarm bell for me.
    Compass calibration every flight for peace of mind is a superstitious ritual.
    It's like pushing the elevator button more to make the elevator come quicker.
    The gods of quadcopter flying don't make any allowances for performing extra rituals.
    Understanding what calibration is for and when it's needed though, improves your safe flying success.
    Calibrating every time is completely unnecessary and introduces the risk of getting a bad calibration.
    Most compass error related crashes are caused by "calibrate-every-time" flyers.
    It's very commonly heard from new Phantom flyers but experienced flyers know how unlikely it is that you would ever accidentally CSC. It just doesn't happen.
    DJI have heard this argument a 1000 times at least and they are not going to change it.
    CSC isn't for stopping your Phantom in mid-air.
    Although you'll read that in forums, it's most unlikely to be used that way.
    It's mostly used for stopping the spinning props on a crashed Phantom when it's a hazard.
    And making an emergency stop harder to activate isn't very good safety.
    FYI CSC does not have a 2 or 3 second delay. It kills the motors instantly
     
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  18. Jussaguy

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    They ARE NOT going to change it? Do you work for them?

    Also, there are multiple reasons for CSC and dropping the UAS in a safe spot IS one of them as is the reason you stated although the board is programmed to turn off in a crash where the props are spinning incorrectly on the ground,. That the CSC is NOT for dropping it in an emergency is a valid reason for a CSC.

    Also, I stated I have OCD. I often recalibrate the IMU and you SHOULD ALWAYS do a compass calibration after an IMU calibration. You should also always do one when you change altitudes (from take off) and I live in LA and am OFTEN taking off at different sea levels.

    That said, I am not saying everyone should. In fact, some people never do and don't have any problems, until they have a problem. I have been flying drones since before the drone revolution began and I have NEVER had a crash from a non fpv/racing style quad like a 250 or something. (DJI products are an Advanced, a Pro, Inspire 1 and an S1000 that my company owns)

    Again, I am not saying everyone should calibrate every time, but I am saying you should calibrate compass for sure when you calibrate IMU, when you crash, and when you change altitudes. Not doing that is irresponsible.

    The pushing the elevator button makes no sense as an analogy because once your press a button on an elevator its coming but after the elevator get there, if you want another you need to press it again. Anything that needs to be calibrated once like a compass, needs another calibration at some point. I've never even had a hint of a fly away.

    The Solo (which I hate) has a 16 rotation calibration for compass and guess what, it's know for its fly aways which might prove your point but in my experience, there is no harm in doing a daily compass calibration or even flight one. It might be overkill but it doesn't harm anything.

    Anyway, this is completely of topic.

    Also, I am not trying to tell people what to do. We are here to share our thoughts and discuss them correct? I disagree that you can cause harm by over-calibrating but I respect your opinion that you think that.

    Again though, I don't think it's necessary to calibrate every flight but it takes 20 seconds and I've never had a "bad calibration". How does one even get a bad calibration. If you know how to do you pre-check list, you will know if your calibration is off. Of course, how many of you actually do your checklist? I actually do and if I had a bad home point or bad compass calibration, I would do it again.

    Everyone always thinks what they are doing is right until they drop a bird. I haven't yet (just knocked on morning wood) and so I will keep my routines but appreciate your input.
     
  19. Jussaguy

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    http://download.dji-innovations.com...en/Phantom_3_Advanced_User_Manual_v1.0_en.pdf

    The above link is the DJI Phantom official manual.

    Page 44 under the title of "CALIBRATING THE COMPASS"

    IMPORTANT: Always calibrate the compass in every new flight location. The compass is very sensitive to electromagnetic interference, which can produce abnormal compass data and lead to poor flight performance or flight failure. Regular calibration is required for optimal performance.

    it DOES also say that you should not calibrate where there is magnets and electronic interference but unless you are taking off from the same spot EVERY time you fly the bird, you are not just disagreeing with the fine people at the DJI forum (which I don't always agree with) but the engineers who created the thing and made the manual.

    A different location doesn't mean like in Phoenix instead of New York, it means your front yard vs. your backyard.

    The reason for that is because the compass, as all compasses work by the magnets in the earth and they are different in every location. I almost never fly in the same location so with all due respect, I will listen to DJI over your opinion. You are right though, a bad compass calibration can lead to catastrophic failure but you know before you send it up if you do your checks if your home point is set right and if your compass is set right.

    Again, don't get me wrong, I don't think everyone needs to do a per flight calibration but if you don't want to find yourself in a "fly away" which is almost always a bad compass, then you will do it especially when you change altitudes, change altitudes or make a major location difference.

    Although I said front yard and backyard, I don't think you need to do that (although I would). But there is DJI in black and white saying if you change your location, calibrate. Listen to them or not. Matters not to me but I thought the official word should make it's way into the conversation.

    Final thought, you know how your iPhone tells you to calibrate every now and then for what is apparently no reason. It's because it needs a calibration of the compass and the phone knows it. If that happened while flying, you better get out of GPS mode and get in to ATTI and fly it back and hope that your cached map is just fine if you are out of line of sight.
     
    #19 Jussaguy, Feb 14, 2016
    Last edited by a moderator: Feb 14, 2016
  20. Meta4

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    No-one here works for or has any connection with DJI.
    I have heard their people say many times (in response to suggestions that CSC be changed) that it is not going to happen.
    I've heard a lot of things true and false about compass calibration but that's the first time I've ever heard it linked to altitude. I doubt it is related.
    Reports involving bad calibrations turn up here every week.
    The most common cause is unnecessarily calibrating the compass on a reinforced concrete structure.
    For any more info on compass related stuff, read this excellent post: Compass Calibration, A Complete Primer