MTOW Question - ATPL
 

Please help me solve this.

Maximum Take-off Mass: 62,800 kg
Maximum Zero Fuel Mass: 51,250 kg
Maximum Landing Mass: 54,900 kg
Maximum Taxi Mass: 63,050 kg
Assume the following preplanning results:
Trip fuel: 1,800 kg
Alternate fuel: 1,400 kg
Holding fuel (final reserve): 1,225 kg
Dry Operating Mass: 34,000 kg
Traffic Load: 13,000 kg Catering: 750 kg Baggage: 3,500 kg
Find the Take-off Mass (TOM)

a) 51,515 kg
b) 55,765 kg
c) 51,425 kg
d) 52,265 kg

Thanks...

Answer - none of the above! I make it 54,925kg. Presume they are wanting to see if you know that catering is part of the dry operating mass. If you do add it on by mistake it makes 55675 and not 55765. Perhaps someone else will know better than me on this one?

answer is 51425, don't forget that the baggage is part of the traffic load as well! all you need to do is add the DOM, which includes the catering, the traffic load, which includes the baggage and the fuel.

51425 is correct. DOW includes catering, Traffic load includes Pax and Baggage weights, Fuel figures are separate again.

the only time you would need the catering weight is if your working from a basic weight, you would also need a crew weight

However! What about contingency fuel (typically 5% of trip fuel). Add that on as well and I get 51515, i.e. answer a. I don't know of many ops manuals that would let you go without any contingency...

The answer is A - 51515Kg.

You need to include the contingency fuel (5% of trip). They are throwing in red-herrings in the form of baggage and catering weights.
If you ever have a slight bit of forgetfulness in the exam, remember that the CAP has the definitions of DOM, etc in the front.

Thanks one and all for the answers. (A) 51,515 was correct, but I had no clue how to get to it. Thanks again.

What makes you think it always 5%

Refer to JAR-OPS 1.255

1.3 Contingency fuel, which should be the higher of (a) or (b) below:

a) Either:

i. 5% of the planned trip fuel or, in the event of in-flight replanning, 5% of the trip fuel for the remainder of the flight; or
ii. Not less than 3% of the planned trip fuel or, in the event of in-flight replanning, 3% of the trip fuel for the remainder of the flight, provided that an en-route alternate is available, or
iii. An amount of fuel sufficient for 20 minutes flying time based upon the planned trip fuel consumption provided that the operator has established a fuel consumption monitoring programme for individual aeroplanes and uses valid data determined by means of such a programme for fuel calculation; or
iv. An amount of fuel based on a statistical method approved by the Authority which ensures an appropriate statistical coverage of the deviation from the planned to the actual trip fuel. This method is used to monitor the fuel consumption on each city pair/aeroplane combination and the operator uses this data for a statistical analysis to calculate contingency fuel for that city pair/aeroplane combination.

b) An amount to fly for 5 minutes at holding speed at 1 500 ft (450 m), [6 000 ft (1 800m) for Concorde operations,] above the destination aerodrome in Standard Conditions.

For the purposes of the exam (i.e. answering the original question). It is necessary to use a contingency of 5% (unless told otherwise within the question).

I was under the impression that, when calculating traffic loads for weight & balance purposes, if it is not specified, ignore it. Could somebody clarify that?

Phil