>>>Note that the temperature was probably around 30F (0 C) at both MCI
. Both airports were experiencing very high winds.
The only thing I'd add to the various explanations here is that on short hops, it really doesn't matter all that much (except in the summer months) what the temperatures are.
All aircraft have a max takeoff weight (what the aircraft can get off the ground with) and a max landing weight (most often a structural limitation) of how much you can land with).
Using 737-700 numbers as as an example, the max takeoff weight is 154,500 lbs. and the max landing weight is 128,000 lbs.
If I were to takeoff from MCI
weighing the max 154,500, I'd burn (consume) about 6,000 lbs of fuel to get to ORD
, and the aircraft would weigh 148,500 lbs on arrival, which is about 20,500 lbs. over the 128,000 lb. max landing weight limit.
What the airline (usually the dispatcher here in the US) does is to take the fuel burn for the flight (6,000 lbs in this example) and add it to the max landing weight (128,000 lbs.) resulting in a weight of 134,000 lbs. Irrespective of the fact that you can actually get 154,500 lbs into the air at takeoff, restricting this flight to 134,000 lbs will prevent the aircraft from arriving too heavy at ORD
The longer the flight, the more the burn, and the closer the the landing-limited weight gets to the max takeoff weight, and at some point, they'll be the same. For really longer haul flying, you'll almost always be takeoff limited.
All this assumes "normal" runway lenths, airport elevations, and non-summer temperatures. Put any/all of those factors into the mix and things can change, but the general concepts are the same.
If a flight is landing weight-limited, it's alot easier to inadvertently overgross it with unexpected payload (extra pax, bags, cargo) shows up, especially if the aircraft is already fueled (tanker fuel, high fuel load due to destination weather). The options in that case are to use child weights (if there are any onboard), defuel some, or pull non-revs, freight, or (last choice) fare-paying passengers.
[Edited 2004-12-17 22:03:03]
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.