and possibly the "per month" refers to the 1775 gates and not necessarely to the number of passengers. Anyway that is one way to "set that calculation at ease"

The source is multiplying the monthly number of emplanements times the number of airports (39) instead times of the number of months (12).

One possible explanation...

enplanement is concerned with the transport (boarding), not the travelling. The difference is in the focus.

--------------------------------------------------
Note added at 13 mins (2004-04-24 22:19:23 GMT)
--------------------------------------------------

http://www.dot.state.ny.us/pubtrans/enpl1.html (for enplanement)
and
http://www.boarding.no/art.asp?id=11621 (for passengers boarding)

Also, passengers boarding is not related only to planes (boats, trains, buses) : http://www.geh.org/ar/strip01/htmlsrc/m197501121999_ful.html

furthermore enplanement is something used for tax purposes:
http://ntl.bts.gov/card_view.cfm?docid=12417

--------------------------------------------------
Note added at 2 hrs 4 mins (2004-04-25 00:10:23 GMT)
--------------------------------------------------

as already mentioned, it refers to passenger enplanement for a matter of taxation which is done on a yearly basis. Also, giving a monthly estimated would not cover the heavy variations between slow months and hectic months.

--------------------------------------------------
Note added at 2 hrs 9 mins (2004-04-25 00:15:42 GMT)
--------------------------------------------------

a. Commercial Service Airports are publicly owned airports that have at least 2,500 passenger boardings each calendar year and receive scheduled passenger service. Passenger boardings refer to revenue passenger boardings on an aircraft in service in air commerce whether or not in scheduled service. The definition also includes passengers who continue on an aircraft in international flight that stops at an airport in any of the 50 States for a non-traffic purpose, such as refueling or aircraft maintenance rather than passenger activity. Passenger boardings at airports that receive scheduled passenger service are also referred to as Enplanements.

http://www.faa.gov/arp/planning/stats/index.cfm

-

--------------------------------------------------
Note added at 2 hrs 46 mins (2004-04-25 00:52:42 GMT)
--------------------------------------------------

Hacene: please drop it already.
There is a definition in the asker\'s question.
There is a definition in the 1st line at your own 1st link.
Remember? It says Enplanements (Passenger Boardings)
Remember now?

Hacene, please explain your choice of words in your last comment.
What are the functions of each of the words in the sentence?
Do you know any synonyms for these words? Please name them and explain
the differences in the usage of different synonyms. I will return your paper graded next week.

240 million would be passenger emplanements, and 160 (400 - 240) million freight and mail emplanements.

Example of a passenger travelling from Minneapolis (Minneapolis St-Paul International airport) to Miami (Miami International airport). Both airports have CNN Network.
Direct non-stop flight Minneapolis - Miami will make 1 passenger = 1 enplanement.
Flight Minneapolis - St Lois - Miami will make 1 passenger = 2 enplanements.
This is where the difference comes from!

--------------------------------------------------
Note added at 2 hrs 53 mins (2004-04-25 00:59:26 GMT)
--------------------------------------------------

St Louis also has CNN network.

--------------------------------------------------
Note added at 15 hrs 21 mins (2004-04-25 13:27:27 GMT)
--------------------------------------------------

ARITHMETIC, sorry