I live in the US and contemplating travel to Europe next Spring and taking a drone with a couple of extra batteries as carry-on, to get some aerial shots. The batteries are 5200mAh (57.72Wh) each on Phantom 2 and 5700mAh (129.96Wh) on Inspire.
TSA Doesn't List Drones
The closest things to drones I could find in TSA's database of packable items are radio controlled helicopters which apparently can be taken on a plane both as check-in as well as carry-on luggage. TSA even gives packing advice. Quoting from the linked site:
Search Results For: RC helicopter
Check or Carry-on
You may transport this item in carry-on baggage or in checked baggage. For items you wish to carry-on, you should check with the airline to ensure that the item will fit in the overhead bin or underneath the seat of the airplane.
To help officers get a clear look at your bag and reduce the need for additional screening, we suggest you pack your bag in neat layers (layer of clothes, layer of electronics, layer of clothes, layer of shoes, etc.) and wrap cords tightly around electronics items.
Even if an item is generally permitted, it may be subject to additional screening or not allowed through the checkpoint if it triggers an alarm during the screening process, appears to have been tampered with, or poses other security concerns. The final decision rests with TSA on whether to allow any items on the plane.
Travelling with LIPOs
Obviously there are substantial technological differences between serious quadcopter drones and toy rc helicopters, which will most likely cause these two items to be treated very differently by airport security. The most important difference is arguably the battery used to power the former. This article from Drone Enthusiast contains a plethora of useful information on the topic. Of interest is the section on LIPO batteries which reads:
Checked-in or Carry-on?
First of all it is very important that LiPo batteries MUST be carried on with you on board the aircraft and CAN NOT be placed in checked in luggage! Swift change in temperature and air pressure make LiPo batteries susceptible to catching fire.
I have been reading threads of discussion online debating if you should declare that you are traveling with LiPo-s when passing through the security inspection. Some reported having no problems even when questioned about the nature of the batteries and even friendly TSA personnel asking them if it is fun to fly quadcopters. At the same time, any Lithium based battery pack falls under IATA Dangerous Goods Regulations involving the shipment of lithium-based batteries on passenger and cargo aircraft. So if you use common sense, you must agree that not declaring things that are classified as dangerous goods is NOT a good idea. You can stretch your luck but don’t think that your LiPo-s will not be seen during screening. Also, please don’t blame me if you follow my advice and still get declined to travel with your batteries. If it happens, it will definitely not be because you declared them.
The quantity permitted is based on watt-hours (Wh). Wh establishes the lithium content by multiplying voltage with the ampere-hours (Ah). For example, 14.40V x 5Ah battery = 72Wh.
The current IATA dangerous goods regulations and your rights as passenger to carry the LiPos with you in carry-on luggage but not in your checked luggage. There are 3 classes of LiPo batteries. Below 100Wh there are no quantity restrictions as to the amount of batteries you can carry. Between 100Wh and 160Wh you are limited to two battery packs total per passenger. Above 160Wh you are not permitted to carry the packs as carry-on.
Followed by the section on transporting the drone as your carry-on luggage which can be summarised as: put the drone in a hard case and check if its size fits into the airline limitations for carry-on. Another important piece of advice is:
Remove Anything Sharp
This might not occur to you automatically, but what you are taking aboard is still a carry-on bag and traveling with lipo batteries on board is not the only possible hazard in the eyes of safety folks. So you WILL need to remove any and all sharp objects such as screwdrivers, blades, scissors also. I would also recommend removing the rotor blades also and placing them in check-in luggage, specially if they are the more rigid and sharp carbon ones.
All in all it is not very common to see people carrying drones as hand luggage hence you should expect a few more questions than usual from airport security officers. In my opinion if you pack the item properly, respect the rules for LIPO batteries, and cross security checks with a smile on your face and an attitude towards explaining what it is you're carrying you should be fine. As usual YMMV and ultimately it is the officer screening you who has the last word on what is and isn't allowed beyond security checkpoints.
I just saw someone carrying a Phantom 4 drone in it's factory case through the Miami International airport, it just had a specialized sticker on the seam of the case. I don't know what the guy went through to get the sticker, but he didn't seam stressed. It was the only carry-on object I saw him with...