Hi!
I took 3 domestic flights with Egypt Air between mid September and mid October. When you check in online, there is a statement that all lithium ion batteries are not allowed for travel and they asked you to certify you don’t have any. So I never checked in online. There’s no point anyway if I still need to do a bag drop. I found this, and printed it/carried it in case I had issues at security or check in.
At the airport, there is a sign at some airports at their check in counter with the chart found in that link. No issues with underwater lights and if you have been to Egypt you know how crazy security is. You can be checked up to 3X before the gates. (1X to get into the airport or check in area, 1X after the check in, and sometimes 1X right before the gate.) I had my rollerboard camera bag opened and inspected each time at each airport and my Big Blue light was on top, Sola hidden away (not on purpose, it fit better further down).
In Cairo, this year and 3 years ago, security before the gates but after check in was concerned about batteries. Any kind of batteries that were not in devices. Nothing specific to my flashlight. There is usually a limit on how much lithium ion (spares, especially) you can carry but they will target any kind of portable batteries including alkaline or ni-mh, gopro lithium ions, etc. 3 years ago they tried to confiscate all my eneloops for my strobes but they were nice and polite. I kept explaining it’s not lithium ion and they called an Egypt air representative/flight crew (pilot/first officer) over and I was cleared. There have been reports on TripAdvisor of people getting all their batteries taken, including camera batteries and all their others. Prior to flying out of Cairo this time, I spread out all my batteries into random places - 2032, gopro, lots of eneloops, CR123…..and also put them into as many devices as I could or make it less obvious. At the third security before the gate, the guy picked up my gopro battery charger with 1 battery in and said just one and I said yes. (I had 4….)
This issue is unique to just Cairo. I hope this helps.