There has been much discussion lately about RTH.  I found this PDF on YouTube from another poster and am providing it here for you.  I, personally, think the Return at Current Altitude option is overlooked.  A lot of people are worried that checking it will leave themselves vulnerable to running into an obstacle on RTH.  Remember, this option only pertains to RTHs from 3-20 meters...not long distances away.  By the time you're inside of 20 meters, you most often have line of sight on the drone and know there are no obstacles between it and the Home Point. From 3-20 meters, the drone just heads home at the current altitude (if that option is selected).  If not selected and RTH initiates (either by you or auto RTH with low battery), the drone immediately lands...not good if you are on the dock and the drone is over water...or on a trail with jagged rocks all around you.

There is a JPG and a PDF chart.

Good reference. Thank you for posting it.  I have had my spark for a year and have only used RTH once or twice so I have never gotten a feel for how it works at the various distance. But, based on this chart, I will be enabling RTH at current altitude.

Good Job, nice work.

LouisP Posted at 2018-7-10 11:59
Good reference. Thank you for posting it.  I have had my spark for a year and have only used RTH once or twice so I have never gotten a feel for how it works at the various distance. But, based on this chart, I will be enabling RTH at current altitude.

Louis

You write: "But, based on this chart, I will be enabling RTH at current altitude."

Be careful. If your Spark starts going home from behind some tall obstacles (e.g. trees) you may be in for trouble. I think it is safer to do higher return to home path. If your Spark starts landing 20 metres from you and you are over the lake, just cancel RTH.

Also, I have seen several cases on this forum which developed like this:
- happy flying
- sudden problems: compass, yaw, speed errors
- Spark drops to ATTI and gets pushed by the wind
- operator in panic does not know what to do
- Spark flies away with the wind
- connection between RC and Spark breaks
- Spark starts auto-landing somwhere
- after few whiles Spark figures sensors are OK and switches to GPS mode
- Spark start return to home
- operator surprised but happy

Imagine if you set RTH at current altitude and Spark had all kinds of obstacles between you and the place it was auto-landing. If it is 100 metres or more away from you, it switches to Sport mode and turns off obstacle avoidance.

Better safe than sorry. I have my RTH altitude set to 30m.

Mirek

If it is more than 20 meters, the Return at Current Altitude is not applicable...it would climb to your preset RTH altitude. Return at Current Altitude only applies to RTHs between 3-20 meters...usually at that distance you are close to the home point and line-of-sight to the drone where you can see any obstacle between you and the drone...then, if there is an obstacle, you can cancel RTH.  And it doesn't go to Sport Mode greater than 100m...obstacle avoidance is disabled and the return speed is faster that normal but slower than Sport Mode...10m/sec or 22.37 mph.

Rustic17 Posted at 2018-7-10 15:14
If it is more than 20 meters, the Return at Current Altitude is not applicable...it would climb to your preset RTH altitude. Return at Current Altitude only applies to RTHs between 3-20 meters...usually at that distance you are close to the home point and line-of-sight to the drone where you can see any obstacle between you and the drone...then, if there is an obstacle, you can cancel RTH.  And it doesn't go to Sport Mode greater than 100m...obstacle avoidance is disabled and the return speed is faster that normal but slower than Sport Mode...10m/sec or 22.37 mph.

Yep - true. Forgot about that. Thanks for setting me straight.

Mirek