If you cant turn your phone on, your holiday could be affected.
You may now be asked to turn on any electronic or battery powered device at the airport checking points (this means telephones, tablets, e-books and laptops).
The new rule only concerns hand luggage, not what goes into the hold.
If you are unable to demonstrate that your device works you will be told it can't go on the flight.
That leaves you with a choice: either hand it to the airline staff (BA and Virgin both say they will it post to any address for you, for free); or keep your phone - but don't get on board.
Airlines will allow you to re-schedule your flight giving you time to get your gadget working - but if that involves a hotel overnight they will not pay.
BA has given me a detailed statement:
I foresee a particular problem for passengers flying to the US as transfer customers, especially those on long journeys.
If they deplete power in their devices while on the first part of your journey, they could hit problems during checks while transferring at Heathrow.
We all know that there are very few charging sockets at airports!
Today a travel industry insider told me that he has heard that extra charging points are being planned to cope with all this.
All this just 10 days ahead of the peak holiday period could affect millions - yet most seem to welcome the new controls as a reassurance rather than a problem.