The use of flight check lists is highly recommended. Commercial operators will need to configure these to their particular requirements. Separate pre-flight check lists may be needed for DataPilot Missions and Manual Camera flights.
On the first flight of the day at any location: If the location is appreciably more East or West of where the last Compass Calibration took place, it may be necessary to re-calibrate it. After the craft is turned on, allow extra time for GPS acquisition. Subsequent flights during the day will go quicker. Also bear in mind that a good GPS fix here is important for the craft to know exactly its "Return to Home" point.
Before any flight: Never take off until after the craft icon (the plane) turns green unless you intend to fly in Manual Mode (no GPS). Tap the craft icon to see info on GPS Satellites, HDOP, and VDOP. A green line filling from left to right also indicates craft initialization. Tap the controller icon to view ST16s status. Because the 520 craft uses its GPS take-off point to key on for Return Home, the ST16s GPS basically is used only to measure horizontal distance to the craft. Ten or more GPS Satellites on the ST16s is needed for this distance to be accurate.
If the camera view is blank or goes blank and the message "Waiting for Video" appears for longer than a minute, turn the craft off, then turn off the ST16s. Wait 15 seconds, then restart the sequence, ST16s first. Allow the ST16s to boot to the craft acquisition screen before turning on the craft. Camera view usually appears in seconds after craft initialization, although EU systems may take a minute or so. See E90 info here: Known-E90-Bugs
On the day's first flight you may need to tap the WiFi icon to connect the camera. If asked for password, default is 1 through 0. If you have to go into the controller WiFi settings to input the E90 password before the camera will connect, redo the password setting using the same 1 to zero.
NOTE: Infrequently, even after several flights without incident, the E90 camera will not connect. The video seems to connect but not the 2.4 control. On screen you receive a "time-out" notice of no connection WITHOUT an offer to input password! In this event simply go into the ST16S Wi-Fi settings, with drone still powered, and connect to the E90 using the password. Now return to the drone control screen and you will find the camera and drone connected correctly. This seems to happen when the ST16S battery is below 50-60%. Unusual bug...
Try to keep the ST16s battery above 50% if feasible, unless you have spare charged batteries. The reason for this is that a depleted ST16s battery, even at 50% for instance, takes considerably longer than a flight battery to recharge. Before any update, charge the ST16S battery completely.
Check and/or Reset ST16S Joysticks, Camera and Speed Sliders. J1, J2, J3, J4 and K1, K2, K3:
If, while hovering without touching controls, the craft slowly rotates, goes up or down, camera rotates with K1 in stop position, camera tilt or minimum/maximum craft speed does not seem correct, a control re-calibrate may be in order. Usually, simply moving the Joysticks around briskly while the ST16S if off cleans the pots. If not, follow this procedure.
Turn on the ST16S (leave craft off). After the connect craft screen appears, tap the Menu Icon 5 times rapidly. A warning will appear. Tap yes, open menu. Down in this advanced menu, first you see a check controls section. Open this and find the control that is not zeroing. Note which controls are J1 through J4 and K1, K2, and K3. The next menu choice is Calibrate Controls. Open this and proceed to move both joysticks, then the K sliders through their full range of motion until all boxes turn green. Then exit the ST16S and turn it off.
IF the problem is still present, use a good quality contact cleaner spray. Remove the applicable rubber stopper on the ST16S rear, apply spray carefully (be sure unit is turned off!), then also apply spray from the front while holding the offending joystick toward the problem direction. Immediately work the joystick back and forth and all around a number of times. Let the spray completely dissipate, 30 minutes? before re-powering. If the problem is stubborn, another spray application may be necessary, but do not overspray.