# Almost crash with px4 1.8.2, custom quad **URL:** \ **Category:** Flight Testing & Log Analysis\ **Created:** [April 16, 2019, 10:35pm UTC](https://discuss.px4.io/t/almost-crash-with-px4-1-8-2-custom-quad/10531 "2019-04-16T22:35:28Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![richard](https://discuss.px4.io/letter_avatar_proxy/v4/letter/r/f0a364/32.png) [@richard](https://discuss.px4.io/u/richard)\ **Post date:** [April 16, 2019, 10:35pm UTC](https://discuss.px4.io/t/almost-crash-with-px4-1-8-2-custom-quad/10531/1 "2019-04-16T22:35:28Z")
Hi. I have a similar sounding issue to another topic, but there is no response yet: > [@2 mid-air crashes using v1.8.2](http://discuss.px4.io/t/2-mid-air-crashes-using-v1-8-2/10521): > > Hi everyone, I have encountered 2 mid-air crashes on last Thursday & Sunday. In both cases, the log file (at least according to my understanding) ends abruptly. I couldn’t find any hardfault logs on the sdcard, but I also doubt both cases were battery disconnect or something like that (I can’t rule that out completely, but I’m pretty sure it isn’t the case) I would appreciate any help on figuring out what happened, or at least what should I do in order to provide more information if those cra… As I am using different flight modes and a different build I posted this as a new topic. **flight logs:** 1. almost crash ([https://logs.px4.io/plot\_app?log=25ffbf0d-1d0a-4f77-a192-d2cef703da3d](https://logs.px4.io/plot_app?log=25ffbf0d-1d0a-4f77-a192-d2cef703da3d)) 2. 2nd try with same mission, inconspicious ([https://logs.px4.io/plot\_app?log=8dd23aa3-a614-4918-892c-29faaa3bdc94](https://logs.px4.io/plot_app?log=8dd23aa3-a614-4918-892c-29faaa3bdc94)) **description** this is my first self-built drone with my first FC. I am using pixhawk v5 with firmware 1.8.2 as can be seen in the lfight logs as well([Redirecting to latest version of document (master)](https://docs.px4.io/en/flight_controller/pixhack_v5.html)). I am just getting started with the drone and step by step testing out different functions. I tried several flight modes and configurations (stabilize, altitude, position, RTL, kill switch function, and mission, battery settings, fail safes). I did not optimize the controllers yet. I noticed in several flight modes “twitching” of the quadcopter in flight and pretty slow control response times, however I held off ([Redirecting to latest version of document (master)](https://docs.px4.io/en/config_mc/pid_tuning_guide_multicopter.html)) being confident to tune the system at a later point. When doing my very first mission flight the quad took off, got to the mission start waypoint, went to the first waypoint with “hover 15 seconds in 15 m alt relative to start position” mission. In this first hover phase approx in the middle of the wait time you can see a big spike on the z-axis. This is when the quad actually turned itself on its head and dropped like a stone. After a couple of meters the quad self stabilized a couple of meters from the ground (maybe 2 -5 meters) and continued the mission without any further issues (flying back up to 15m height, finishing the wait and turning to fly to 2nd waypoint). ![](https://discuss.px4.io/uploads/default/original/2X/3/3a654777978b93cdc6d454b09148ce80a29e8643.jpg) The second flight directly succeeded the first flight, without any changes to the system or loading the battery. Does a more advanced px4 user see any flaws or problems that could have caused this issue? Thank you for any input. ---
**Author:** ![richard](https://discuss.px4.io/letter_avatar_proxy/v4/letter/r/f0a364/32.png) [@richard](https://discuss.px4.io/u/richard)\ **Post date:** [May 12, 2019, 4:48pm UTC](https://discuss.px4.io/t/almost-crash-with-px4-1-8-2-custom-quad/10531/2 "2019-05-12T16:48:26Z")
Is there any advice on why this could have happened or how to find out more about the root cause of this issue? ---
**Author:** ![kpetrykin](https://discuss.px4.io/user_avatar/discuss.px4.io/kpetrykin/32/4110_2.png) [@kpetrykin](https://discuss.px4.io/u/kpetrykin)\ **Post date:** [July 4, 2019, 12:17pm UTC](https://discuss.px4.io/t/almost-crash-with-px4-1-8-2-custom-quad/10531/3 "2019-07-04T12:17:06Z")
Sorry for late answer %) but it seems like you have short-time one motor disabling (first one, right-top). In 3D-view on 1:40 we can see half-flip and on the “Actuator outputs” plot there is a high signal on Output 0 while low one is on the others: ![image](https://discuss.px4.io/uploads/default/original/2X/f/f2ebd2214aaee9a8e770d9f41a592ba65c72a989.png) In this case you shoud check your first motor, it’s ESC, wires and soldering.