Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
speedracer1407
Topic Author
Posts: 330
Joined: Fri Dec 24, 2004 4:19 pm

When Is Weight, Fuel, Power Finalized?

Tue Apr 04, 2006 2:07 pm

Given the numerous factors involved in calculating cargo, fuel, wind, power, etc for each flight, when are these factors finalized? Ok, wind changes constantly, both on the runway and aloft. But are fuel loads and cargo loads decided last-minute because they're inextricably linked to wind conditions? Are they calculated hours or days in advance with a margin of error to account for varioations in weather, additional PAX, or cargo?

O
Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
 
Tristarsteve
Posts: 3660
Joined: Tue Nov 22, 2005 11:04 pm

RE: When Is Weight, Fuel, Power Finalized?

Wed Apr 05, 2006 3:50 am

Well not many sectors are limited to WAT conditions. Most short haul aircraft (except perhaps transcontinental in the USA) are limited by max ZFW. Most aircraft can take full pax and baggage (though we sometimes have problem with A320-100) and some freight. The planners know about how much freight to accept, and the dispatcher can offload it on the day if Max ZFW is exceeded. Only sectors over around 3 hours can be a problem with Max TOW., and then usually because the airline has a limited Max ZFW for economy. (When you buy an aircraft you can specify the max TOW. More TOW costs money. Airlines specify lower TOW to save on landing fees.).
On long haul the scenario changes because the runway can be the limiting factor. But this is taken into account months before when the planners work out the payload and how many pax or how much freight to accept.
This can be hit on the head on the day with an icy/slippery runway, which can reduce TOW by 30 tons.
I depart B777 on a 12 hour sector every day and with a dry runway there is always weight to spare. Max pax and full freight holds and still 30 tons under the limiting weight. (Max ZFW or Max TOW or Max LDW. whichever is the lowest).
Then about 2 hours before departure a Computor flight plan is generated based on the expected ZFW and weather. The pilots look at this about 45mins before departure and choose a fuel figure. Occasionally if there is a limiting weight they may wait until the Final ZFW is produced before filling the tanks to Max TOW, but this is not so common nowadays.

Who is online

Users browsing this forum: No registered users and 10 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos