Iris+ with about 30 flights on it went down in a salt water bay this morning with a brand new Hero 3+ black edition camera in a naked housing, nose mounted. Took off from a boat in standard flyting mode, using only the 3DR radio. As soon as it lifted off I noticed a forward drift and a slight right turn. As the drift became worse and full opposite control input was not enough to even keep the copter level, I switched to Loiter (GPS) mode in hopes of the copter stabilizing, but it only accelerated the unbalance. The drift became a more pronounced drift and a yaw to the right. At this point the Iris was only about 20 feet in the air. Now to add to my lack of radio authority the Iris began to descend very slowly as the drift and yaw continued until it contacted the water and immediately sank, followed by pillows of smoke from the LiPo battery catching fire. This was a very large brackish body of water and the Iris and GoPro camera are both indeed unrecoverable. I've had a conversation with the tech department at 3DR this morning. Due to the Iris being unrecoverable, no data from Pixhawk is able to be reviewed as to what exactly happened. 3DR's tech person heard my story and is now discussing options with his supervisor, as I am patiently awaiting a call back soon. I am a FAA commercially licensed helicopter pilot ( 10 years) and have been operating UAV's (small quads to large octo's for 2 years). I'll be happy to follow up with the results of my awaited return phone call from 3DR.
When operating in a potentially hazardous environment, it always pays to have the telemetry enabled incase there is a flight failure that leads to the loss of the aircraft.
A review of the telemetry could have helped prevent future failures of this kind if you chose to continue using the IRIS+.
I believe it's recognised that apm:copter will not work well if you take off from a boat, due to issues with the gyro calibration I think.
Just a suggestion, next to a flowing lava field, salt water is about the most hostile environment I can imagine for a non waterproof quadcopter.
The moment any exposed electronic component gets even the smallest amount of salt water, mist, spray, anything you are immediately short circuit city toast.
The Iris is a great copter, but a salt water or salt spray area is way out of it's element.
Strongly suggest you look at a well waterproofed Aquacopter or one of the more expensive fiberglass with camera port quadcopter shells that are really designed for operating in this environment.
And even then, the motors are problematic, even though the best ones have epoxy coated windings they are not really designed for salt water environments.
The aluminum cases will corrode and the bearings last a very short time when exposed directly to salt water even with a flush and re-lube procedure.
I agree that telemetry can help, but a marine environment is really hard on these things even if you do the best you can.
But at least you need a copter that can float (Aquacopter) so you can at least recover it when it goes down.
Basically you fly off a boat in the water with a non buoyant copter, consider it disposable.