View Full Version : TOD Query
Cat3508
20th Mar 2013, 06:18
How do you calculate TOD ? Do you use the 1 in 3 rule, rely on the FMC's prediction, or do you contact ATC first, and wait for descent instructions.
Intruder
20th Mar 2013, 18:32
Both of the first 2.
4) Just wait for the Captain to ask why you haven't?
763 jock
22nd Mar 2013, 15:39
Bit of everything really. My outfit, we use the FMC. This will decide when to start down based on track miles, cost index and forecast winds that have been entered. Some arrivals you end up dragging the thing in anyway due to level restrictions on the STAR.
Lots of variables and every arrival is unique in one way or another.
Denti
22nd Mar 2013, 21:48
FMC supervised by a cross checking pilot based on rules of thumb for the type, usually around 1 in 3 to 2.5. To have correct values for the FMC download the latest descent winds within the last half an hour before TOD and enter any expected restrictions.
And then, when you've done all that, ATC will get you down to FL180 with 120nm still to go. (I/b to London airports anyway).