Drone Emergencies: Lost Link, Flyaway, Fire

Most drone emergencies are not dramatic. The link drops, the GPS wanders, a battery sags or heats up. Part 107 handles them with two ideas: plan the response before you launch, and in a real emergency, do what safety requires. 14 CFR §107.21 lets the remote pilot in command deviate from any rule in Part 107 to the extent needed to meet an in-flight emergency, and the pilot sends a written report only if the FAA asks for one.

What does the emergency rule allow?

Anything needed to keep people and property safe. The FAA's Remote Pilot Study Guide gives an example: if the aircraft has a battery fire, the pilot may need to climb above 400 feet AGL to reach a safe landing area, and a report is needed only if the FAA requests it.

The rule covers deviation, not carelessness. Before flight, §107.49 requires the remote PIC to brief everyone directly participating on the operating conditions, emergency procedures and contingency procedures.

What happens when you lose the control link?

The FAA's AC 107-2A says that if the remote PIC loses the control link during an automated flight, the aircraft continues the programmed mission or returns home to land. For a loss of visual line of sight, it lists landing immediately, entering a hover, or a return-to-home sequence, depending on the aircraft's capabilities.

That makes the return-to-home setup part of the preflight:

• Set the return altitude above every obstacle on the way back, but within the 400-foot limit.
• Confirm the home point after the aircraft acquires GPS, from the minimum number of satellites the manufacturer specifies, which AC 107-2A lists in its preflight items.
• Decide what the aircraft does on link loss: return, hover or land. The right choice depends on the site.

Why do flyaways happen?

AC 107-2A points to the radio link. Most small drones use the unlicensed 2.4 GHz and 5.8 GHz bands, the same ones used by Wi-Fi, and interference in dense housing or office areas has led to loss of control and flyaways. Both bands are line of sight, so the link fails behind obstacles, which keeping visual line of sight also helps prevent. The VLOS post covers that rule.

Losing GPS has a different effect. Many drones hold position with GPS; without it, the aircraft may drift with the wind while you still have control. The ACS lists GPS loss and its consequences as its own knowledge element.

What does the FAA say about lithium battery fires?

AC 107-2A says lithium batteries are highly flammable and can catch fire when they short-circuit, are charged improperly, get too hot, are damaged in a crash, are mishandled, or are defective. Its advice is to follow the manufacturer's recommendations for handling and use. The ACS splits the topic into safe transport and inspection, safe charging, safe use, and the risks of lithium fires, and the study guide refers pilots to the FAA's safety alerts on fighting lithium battery fires.

When must you report an accident?

Under §107.9, within 10 calendar days, when an operation involves serious injury to any person or any loss of consciousness, or damage to property other than the drone, unless repairs cost $500 or less or the property is worth $500 or less. The registration and reporting post covers how to file.

What the exam asks about emergencies

Emergency procedures are ACS task UA.V.C: emergency planning and communication in UA.V.C.K1, lithium batteries in K2, loss of control link and flyaways in K3, and GPS loss in K4. The FAA's sample questions include who briefs participants on emergency procedures (the remote PIC) and when a deviation must be reported (on FAA request). The medical emergencies post covers the human side.

Many emergencies start with a hazard you could have avoided; the flight hazards post covers wires, plumes and balloons.