# Would knowing the exact weight that has been loaded on a commercial plane and it's distribution be useful? [duplicate]

There's been a bit in the media about weighing passengers in order to get more accurate take off weights for commercial planes. I'm guessing the delta between a heavy set of passengers and a light set might be 3000 kg. If there was a cheap way of determining the weight that has been loaded onto a commercial jet would it be valuable out not, given this level of weight difference? I am after an actual cost. What is the cost of an airliner carrying the additional fuel required by current rules if it assumed the overall mass estimate is 3000kg too high throughout its life? It won't be using that fuel but it will have to carry it.

• "current estimations are enough" ??? Investigations need facts, or, better yet prevent the accident before it happens. This question is not only about weight, but also distribution. It does not seem to be a duplicate. – Robert DiGiovanni Apr 22 '19 at 17:53
• RE edit, are you asking about the accuracy of fuel loading? Because fuel loading is not related to the mentioned passenger-weighing. Please clarify further. If it is the cost of carrying extra fuel, then check this please: How much fuel is burned to carry the trip fuel? – ymb1 Apr 24 '19 at 9:28
• A very important consideration would be adequate fuel reserve safety margin for headwinds, go arounds, unanticipated delays, etc. as compared with total weight of aircraft. A study of frequency of fuel starvation incidents with current margins would also be in order. – Robert DiGiovanni Apr 24 '19 at 14:36
• Ymb1 - I have edited the question to make it clearer. Thanks – DoubleD Apr 25 '19 at 21:04

YES.

The obvious solution is to roll the plane over a scale. Useful CG data can also be obtained by weighing the front wheel and comparing its torque to known values. A light front wheel means an aft CG. This could be corrected by moving fuel BEFORE the plane is airborne, as well as while in flight.

Of course, moving passengers and cargo are an option too.

For example the plane weighs in at 2200 lbs total on the ramp ready to go. The nose wheel weight is 200 lbs. The distance between the main and nose wheels is 11 feet. The aft CG limit is 0.75 feet forward of the mains.

CG is calculated as follows: 200 lbs/2200 lbs = 1/11. CG is 1/11 * 11 feet = 1.00 feet forward of mains. CG is with in limits.

And how accurate weighing the nose wheel can be (due to long torque arm):

Nose wheel weight 100 lbs. Total weight 2200 lbs. 100 lbs/2200 lbs = 1/22. CG is 1/22 * 11 feet = 0.500 feet forward of mains. CG is NOT in limits.

• Technically nothing incorrect here, but the question had to do with larger commercial jets. 2200 lbs is around the weight of a Cessna 172, and yes, small planes are very sensitive to CG as well as overloading. I agree with Ymb1's answer on the duplicate question linked above. – Michael Hall Apr 22 '19 at 16:42
• @Michael Hall I drive a 40 ton tractor trailer. We go over scales. As a matter of fact, this approach is "scalable" through a wide range of types. The benefit is being able to do gross weight and CG with some simple algebra. – Robert DiGiovanni Apr 22 '19 at 17:50
• And I promise I will not attempt to answer authoritatively on any questions pertaining to 40 ton tractor trailers. – Michael Hall Apr 22 '19 at 17:54
• @Michael Hall OK, as a comment (answers should be authoritative), 3 reasons. Aircraft are being designed to tighter aerodynamic specs, yet a huge amount of variables such as runway length, weather, traffic patterns, payload, and CG remain. As planes are tweaked to perfection, their tolerance to these variables may be less. Airports designed in the last century also need to keep pace, and gov't regulations for Passenger Aircraft could be such that over competition by Majors for the most "efficient" planes will not lead to danger. Weighing and fuel transfer preflight could make it safer. – Robert DiGiovanni Apr 22 '19 at 18:42
• Then my advice is to invest in a system of scales and make your case to industry. Again, I am confident that this has been considered and decided against by professionals with a lot more specific knowledge on the subject than either of us. – Michael Hall Apr 22 '19 at 18:55