4 ms·

After reading the article, I'm kind of confused. What is the public-safety concern with this behavior?

rhizome 12y ago
It's a dog-whistle that they'd like it to be a TSA crime.
hayksaakian 12y ago
none, it's all BS. the only real point they have is that if many people buy A-B-C tickets, their calculations will expect many physical people to be on the B-C flight. Here is a contrived situation that they might present: Aircraft are fueled to certain amounts based on the number of passengers they have. If an airplane takes off from SEA to LAX, it does not want to stop right away and land, minutes after taking off. The landing might be too "hard" since the plane weighs too much. Normally what happens is the plane will either take off with less fuel, or it has to circle around in the air, burning off excess fuel before landing. If you have an airplane flying from SEA to LAX to DFW, and too many people get out at LAX, and don't make the LAX-DFW flight, then the weight calculations on takeoff and landing at LAX and DFW will be very different. Now keep in mind in the real world, this probably won't make any difference, since more than 2% of travelers don't do this. Also i have not looked up what kind of weight impact the actual passengers are supposed to have relative to the actual airplane.
- bdonlan 12y ago
  Passenger (and luggage) weight makes a huge difference for fuel burn and overall weight. That said, planes that are above maximum landing weight are generally bound for a very distant destination - on an SEA - LAX leg the plane is almost certainly nowhere near full on fuel, it under the maximum landing weight from the start, and can land immediately without a problem. If it is going for somewhere far away, however, that gives the crew plenty of time to burn extra fuel on the way by operating inefficiently (turning on the APU, flying at inefficient altitudes or airspeeds, etc), and in any case if enough passengers are missing that the fuel burn will change significantly that'd probably push it back down under the landing weight limit. The whole circling to burn fuel or fuel dumping thing usually happens when the plane has to make an emergency or unexpected landing; here the typical scenario is that the plane is fully loaded with passengers and luggage, and has nearly-full fuel tanks for a long cross-country or international route. Shortly after takeoff, a technical issue is identified, and the plane needs to shed weight before landing to avoid damaging the landing gear and requiring a costly inspection before returning to service. The other scenario where circling to burn fuel can happen is if there's a wet runway or other such issue that reduces braking performance. Again, though, this is mostly an issue if you have a fully loaded plane ready for a very long route.
- userbinator 12y ago
  AFAIK most airlines don't charge passengers by weight, so there are probably significant variances between flights anyway. Ideally the planes would be weighed after being loaded to calculate how much fuel they should need, but that might take too long.

It's a dog-whistle that they'd like it to be a TSA crime.

none, it's all BS. the only real point they have is that if many people buy A-B-C tickets, their calculations will expect many physical people to be on the B-C flight. Here is a contrived situation that they might present: Aircraft are fueled to certain amounts based on the number of passengers they have. If an airplane takes off from SEA to LAX, it does not want to stop right away and land, minutes after taking off. The landing might be too "hard" since the plane weighs too much. Normally what happens is the plane will either take off with less fuel, or it has to circle around in the air, burning off excess fuel before landing. If you have an airplane flying from SEA to LAX to DFW, and too many people get out at LAX, and don't make the LAX-DFW flight, then the weight calculations on takeoff and landing at LAX and DFW will be very different. Now keep in mind in the real world, this probably won't make any difference, since more than 2% of travelers don't do this. Also i have not looked up what kind of weight impact the actual passengers are supposed to have relative to the actual airplane.

bdonlan 12y ago
Passenger (and luggage) weight makes a huge difference for fuel burn and overall weight. That said, planes that are above maximum landing weight are generally bound for a very distant destination - on an SEA - LAX leg the plane is almost certainly nowhere near full on fuel, it under the maximum landing weight from the start, and can land immediately without a problem. If it is going for somewhere far away, however, that gives the crew plenty of time to burn extra fuel on the way by operating inefficiently (turning on the APU, flying at inefficient altitudes or airspeeds, etc), and in any case if enough passengers are missing that the fuel burn will change significantly that'd probably push it back down under the landing weight limit. The whole circling to burn fuel or fuel dumping thing usually happens when the plane has to make an emergency or unexpected landing; here the typical scenario is that the plane is fully loaded with passengers and luggage, and has nearly-full fuel tanks for a long cross-country or international route. Shortly after takeoff, a technical issue is identified, and the plane needs to shed weight before landing to avoid damaging the landing gear and requiring a costly inspection before returning to service. The other scenario where circling to burn fuel can happen is if there's a wet runway or other such issue that reduces braking performance. Again, though, this is mostly an issue if you have a fully loaded plane ready for a very long route.
userbinator 12y ago
AFAIK most airlines don't charge passengers by weight, so there are probably significant variances between flights anyway. Ideally the planes would be weighed after being loaded to calculate how much fuel they should need, but that might take too long.