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Originally Posted by Brian Carlton
Correct on takeoff.
However, most cargo planes takeoff with far less fuel than a passenger plane going the same distance. As an example, a 747 freighter travelling from NY to Japan will make a fuel stop in Anchorage. The fuel load departing NY is about 200,000 lb. and the freight can be almost 250,000 lb. It lands with 250,000 lb. of freight and minimal fuel.
The passenger aircraft departs NY with 350,000 lb. of fuel and about 80,000 lb. of passengers and bags. It lands with the the same 80,000 lb. of passengers and bags and minimal fuel.
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Sort of.
The weight of an aircraft is dependent on quite a few things.
Cargo planes are not necessarily heavier that an equivilent passenger aircraft. The aircraft has a maxiimum certified takeoff and landing weight that is determined by the manufacture. Not all cargo aircraft are made that way. some are used ex-passenger aircraft and some are freighters right off the assembly line. But the manufacture determines the weights. IF the aircraft is heavier than the passenger aircraft that just landed. They will fly at a faster speed. My aircraft speed is based on the weight on approach. Heavy, we fly a faster "ref" speed. Gusty winds. We add some speed, based on our companies formulas.
An interesting note. UPS and FEDEX usually bulk out before they gross out. They run out of room before the weight of the cargo causes them to hit their max weight.
So why do the cargo planes seem to be having the difficulty here.
An airlines cargo operation my have more junior crews on it only due to the more night flying on the freight operation. That will hold true her in the US. But international operations usually require night operations on every trip. Our South America trips are a double all nighter. Night flight going down and coming home. Out of our international lines on the 767, The South American runs go the most junior for line holders. Europe is the most senior and Hawaii is next.
Another factor, and I'm not saying cargo crews are less experienced ( total flight time). It could be that the photographer was up at the times that the cargo planes were arriving. Just a coincident. If 8 am in Hong Kong is when the cargo planes arrive and the winds were blowing like crazy. They were the ones shooting the approaches. He clicked the camera and the conclusion is that the cargo planes are the problem.
I find the cargo operators do a fine job. If they didn't you would be hearing about it in the newspapers all the time due to crashes.
Actually FEDEX and UPS do about 50% at night and 50% during the day, flying wise.
Another factor, The freight dogs may be flying all the time at night, arriving at sunrise, and doing this all the time produces fatigue. This is a factor in a night freight operation. Once you get your circadian clock all screwed up, it does affect judgement.
The majority of accidents in aviation now adays are a change of events. Not just one item ( usually). I feel that these landings were just because it was really windy, A bad approach (the IGS landing system at Hong Kong), International night/day operations and possibly a cultural "saving face" or "not wanting to fail" philosophy that prevented the crew from initiating a go arround. This has been found to be a factor in Korean Airlines operation, Saudia, and some other airline operations. Pilots tend to "mission oriented" which means we have a job to do and were going to do it no matter what. well that no matter what may meana bad landing etc. The aviation community is working very hard to ingrain a phlosophy of "not finishing a mission" is OK or a divert/ go around IS part of the mission. The airlines actually test for the "mission oriented" makeup. It is part of what makes up a pilot, this philosophy is what allows us to do the job safetly. But all personallity makups have ther downside. this "mission oriented" philosophy is one of them.
Part 2.
For Brian, 2 747's going from NYC to Hong Kong will burn "about" the same fuel ( it is weight dependant). They will probably have the same fuel for alternates, They will probably have the same amount of cargo/passenger weight. The cargo plane will be about the same as the passenger plane. Passenger planes have a lot of cargo in the belly when they fly. And on interantional flights, airlines really try to max out the aircraft ( in $$$) . The cargo plane is doing the same thing. But as I posted above the cargo plane usually bulks out first.
Also the "fuel stop in Ancorage actually cost the airline more than the nonstop. In the MD80 if I stop for fuel instead of going non stop it cost American about $10,000. So the airlines wants to fly non stop as much as possible. It causes the average cost per seat mile to drop the longer you stay in the air. Our highest burn rate is are in the lower atmosphere. In addition to all the ground support expense.
Now if the cargo freight company is picking up $150,000 worth of revenue, go for it. If it is just for fuel, it really cost them. Its a balance that each airline has to figure.
Arrival fuels will probably be the same for both planes. My minimum for the MD80 is 6000 lbs of fuel. If I need an alternate I will land at say DFW with more. But I will land at the alternate with 6000Lbs. My personal minumum. So the flight to DFW, with an alternate ( which requires, say 4000Lbs) requires 10,000 at DFW, If I dont' divert. If were are going to hold I should have more fuel or I will have to divert as soon as I get holding instructions.) This is all calculated on the flight plan based on the weather and aircraft weight at takeoff. No passengers and I burn less fuel enroute, A full load and I burn more.
Aircraft are designed with a seesaw type affect with fuel and weight. I can hold full fuel but then not full passengers, and visa versa. Then a maximum landing weight comes into play.
Examples. My normal empty operating weight is about 87,000# my maxumum fuel load is 39,000# my maximum takeoff weight is 150,000#. So we get 126,000# with the plane and max fuel that leaves about 22,000 in cargo and passengers. ( another little thing is called maximum zero fuel weight. This is the structural limit for cargo/pax without fuel. The fuel in the wings stabalizes the aircraft and helps the structural design limits) Now lets say on this flight I have 25,000 of cargo/pax. That means I can only carry 36,000 Lbs of fuel. A flight form DFW to Seattle might have a problem becasue of headwinds. From SEA to DFW no, the're tail winds. This is where you start to get passenger restricted flights. OR another thing is maximum landing weight. I cannot touchdown above 130,000# If I'm going to burn 7000# in a flight, DFW to TUL I can only weight 137,000# based on my landing weight, not the 150,000# structural weight.
I see I have rambled. I'll stop.
Dave