Originally Posted by
Bigmouth
On a plane with 150 seats and 148 passengers the attendants will always count the passengers and not the empty seats. They do this at all airlines all over the world. Nobody knows why. If you ask them they will answer something about infants or pax in the lav or just mumble something incomprehensible. So sadly we will never know.
It's quite straightforward. Most carriers, even those where you think "the planes are all the same" have a range of seating configurations, maybe differing by just 1. A Seat row may have been removed as unserviceable, or the fleet may be halfway through a reconfiguration. So you can't do this without checking the configuration. Then you can get arithmetic errors, and a range of other issues.
It is also appropriate to have just one method of doing the headcount. If you have 150 seats and only 30 passengers today do you still count the empty seats ? What if you have 90 passengers, where do you draw the line?
There is less scope for error if you have just one procedure, done the same every time. Count the passengers, look at the manifest and compare.