Luggage trackers

There are a number of options out there, they are not terribly expensive, but I would look at a few things.

• Battery Life: What is the typical life of a charge? consider that you will need several days of battery life to be effective.
• Most of these devices use a cell phone signal for tracking. Great, cell phone signals are everywhere, except when the airplane is in the air, at many places in the airport, even if the signal is unavailable if sitting in an underground baggage facility at an airport.
• To what degree will it help you? If it is just going to let you know it is somewhere in the vicinity of London Heathrow, that has some comforting value, but little practical value.

Two questions.
1) Since these devices use mobile phone technology. What about the requirement to turn off mobile phones (or put them in aircraft mode) when in flight. Aren't they breaching that?
2) What about phone standards. Are they GSM, US CDMA, or some other standard? And what frequencies do they use? I.e. do they work in all countries (it got sent to Grand Fenwick, which uses a different frequency / standard)?

And most airport warehouses etc. are big metal clad buildings. Perfect for blocking radio signals.

Since these devices use mobile phone technology. What about the
requirement to turn off mobile phones (or put them in aircraft mode)
when in flight. Aren't they breaching that?

They use Bluetooth

Battery Life: What is the typical life of a charge? consider that you
will need several days of battery life to be effective.

They use watch type batteries and will last a year before needing to be replaced.

Most "lost" luggage isn't truly lost. In most cases the airline knows exactly where it is due to the bar codes on the luggage, it's simply takes time to return it to you because it can be thousands of miles away.
The trackers on the market are designed to thwart theft in public places like train stations or hotels. They use Bluetooth signals to determine how far away they are from your smartphone, and an alert on your phone will go off when they "wander" off. In theory you might be able get your bags back if you react fast enough. But in practical term they are better for finding stuff like lost car keys.

If it's got a lithium battery in it, the airlines are banning those due to onboard fire concerns if the batteries crushed.

They use watch batteries.