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The controller and drone lose the ability to send and receive commands (Uplink).

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Pre-flight Preparation

1. Set Contingency Behaviors. For long range and BVLOS operations, reference the CONOPS provided. The following is recommended for short and medium range missions with sUAS equipped to respect one or more of these parameters:
   • Time to wait before RTH — 10 seconds
   • Drone Looks — Towards Return
   • Land Upon Return — Yes
   • Wait Before Land — No
2. Limit Radio Frequency (RF) Interference.
   1. For susceptible controllers (like X10D), ensure sources of RF interference are far enough away.
   2. Stay back from environmental sources of RF interference (cell towers, power lines)
3. Ensure Optimal Uplink.
   1. Position antenna and maintain line of sight for signal transmission according to manufacturer guidance.
   2. Program controller (if able) to broadcast at the maximum power allowed by regulation.
4. Appropriate Frequency Choice. If flying with other UAS in the area that require chosen controller signal frequencies (like Skydio X2D; X10D), verify 50MHz separation between each UAS.

Emergency Response

1. Immediate Actions:
   1. Verify controller signal indicator shows lost link
   2. Verbally announce “Lost Link” to your sUAS Aircrew & nearby Teams or persons
   3. Attempt initiating the RTH function
   4. Anticipate programmed sUAS contingency behaviors being triggered
   5. Check controller
      1. Correct antenna orientation?
      2. No transmission line of sight obstacles?
      3. Cabling secure? (as applicable)
      4. Overheating / too cold?
2. Secondary Actions.
   1. Change broadcast frequency (if controller allows)
   2. Get closer to the drone while keeping it within Visual Line of Sight
3. Recovery
   1. If link cannot be reestablished, prepare for uncontrolled landing
   2. (As needed) Use the “Last Know Position” and “Last Flight” features of the sUAS (if available) to establish an area of probability and terrain landmarks.