Originally Posted by
KARFA
so yes 2 chimes is about to takeoff usually on runway entry at LHR. but for places where you have a significant back track (e.g. INV, CFU) you may get that later just as they are about to turn at the end to line up rather then on runway entry.
1 chime shortly after takeoff, and again about 1-2 minutes before landing, is once gear is up and gear is down respectively.
it is just supposed to be 1 chime usually somewhere between 6,,000-10,000ft for seat belts off, basically once it is deemed safe to do so. usually cabin crew will be up well before that, especially for the shorter routes. occasionally you do get 2 chimes for "releasing the crew" which I can only assume is because there is a reason they should remain seated until a positive signal by the flight crew - expected turbulence maybe? otherwise default is crew decide when to release themselves and don't get a chime to do that.
So the SOP for all fleets is that the flight crew will give the cabin crew a signal just before take off, it is a last chance to sit down if they had to get up for any reason. On the Airbus it is the 2 chimes, we use the No Smoking switch, which is hard wired to be on all the time, but still has a chime linked to the switch. Other aircraft may use a dedicated system for this.
As KARFA stated you get a chime once the gear is up, this again used to be associated with the No Smoking signs. And normally we turn off the seat belt signs at 10000ft, this is a weather and conditions dependent flight crew selection and refers to the passengers, cabin crew are not bound by the seat belt signs. Sometimes, if turbulence is expected on departure we use a “double-ding” to the cabin crew to let them know we think it is okay for them to be up and about after take off - this would be a pre-briefed event.