[{"data":1,"prerenderedAt":406},["ShallowReactive",2],{"learn-\u002Flearn\u002Fmass-and-balance-basics":3,"learn-nav-\u002Flearn\u002Fmass-and-balance-basics":378},{"id":4,"title":5,"body":6,"date":307,"description":308,"draft":309,"extension":310,"faqs":311,"howTo":321,"keyTakeaways":331,"meta":332,"navigation":333,"path":334,"quiz":335,"seo":362,"series":331,"seriesOrder":331,"sources":363,"stem":375,"topic":376,"__hash__":377},"learn\u002Flearn\u002Fmass-and-balance-basics.md","Mass and balance basics",{"type":7,"value":8,"toc":297},"minimark",[9,13,19,24,57,61,64,116,120,123,190,201,206,225,229,256,260,286,290],[10,11,12],"p",{},"An aircraft can be under its maximum weight and still be unsafe to fly, because where the weight sits matters as much as how much of it there is.",[14,15,16],"blockquote",{},[10,17,18],{},"This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.",[20,21,23],"h2",{"id":22},"two-questions-not-one","Two questions, not one",[10,25,26,27,31,32,35,36,43,44,50,51,56],{},"Loading an aircraft asks two separate questions. Is it ",[28,29,30],"strong",{},"too heavy","? And is the weight ",[28,33,34],{},"in the right place","? Exceed the maximum mass and the aircraft may not climb or stop in the distance available; put the ",[37,38,42],"a",{"href":39,"className":40},"\u002Flearn\u002Fglossary#gt-centre-of-gravity",[41],"glossary-link","centre of gravity"," outside its limits and the aircraft can become unstable, hard to recover from a stall, or simply uncontrollable in pitch. Both have to be answered before every flight, and the method is the same arithmetic either way. The reference works are the ",[37,45,49],{"href":46,"rel":47},"https:\u002F\u002Fwww.faa.gov\u002Fsites\u002Ffaa.gov\u002Ffiles\u002F2023-09\u002FWeight_Balance_Handbook.pdf",[48],"nofollow","FAA Aircraft Weight and Balance Handbook (FAA-H-8083-1B)"," and Chapter 10 of the ",[37,52,55],{"href":53,"rel":54},"https:\u002F\u002Fwww.faa.gov\u002Fregulations_policies\u002Fhandbooks_manuals\u002Faviation\u002Fphak",[48],"FAA Pilot's Handbook of Aeronautical Knowledge",".",[20,58,60],{"id":59},"the-vocabulary","The vocabulary",[10,62,63],{},"A handful of terms do all the work:",[65,66,67,74,80,86,92,98,104,110],"ul",{},[68,69,70,73],"li",{},[28,71,72],{},"Datum."," A reference plane chosen by the manufacturer, often at the nose, firewall, or leading edge. Everything is measured from it.",[68,75,76,79],{},[28,77,78],{},"Arm."," The horizontal distance from the datum to an item of mass. Arms behind the datum are positive; arms ahead of it are negative.",[68,81,82,85],{},[28,83,84],{},"Station."," A location along the aircraft expressed as its arm, so \"station 2.30\" means 2.30 m aft of the datum.",[68,87,88,91],{},[28,89,90],{},"Moment."," Mass multiplied by arm. It is the turning effect of that mass about the datum, and it is what you actually add up.",[68,93,94,97],{},[28,95,96],{},"Basic empty mass."," The mass of the aircraft itself with its standard equipment and unusable fuel.",[68,99,100,103],{},[28,101,102],{},"Useful load."," What you can add: crew, passengers, baggage, and usable fuel, up to the maximum.",[68,105,106,109],{},[28,107,108],{},"Centre of gravity (CG)."," The balance point of the whole loaded aircraft: the total moment divided by the total mass.",[68,111,112,115],{},[28,113,114],{},"CG envelope."," The range, between a forward and an aft limit, within which the CG must stay.",[20,117,119],{"id":118},"a-worked-example","A worked example",[10,121,122],{},"These are illustrative figures, not data for any real aircraft. Work each item's moment as mass times arm:",[65,124,125,140,154,166,178],{},[68,126,127,128,132,133,136,137,56],{},"Basic empty mass ",[129,130,131],"code",{},"700 kg"," at arm ",[129,134,135],{},"2.30 m"," gives a moment of ",[129,138,139],{},"1610 kg m",[68,141,142,143,146,147,150,151,56],{},"Pilot and front passenger ",[129,144,145],{},"160 kg"," at ",[129,148,149],{},"2.05 m"," gives ",[129,152,153],{},"328 kg m",[68,155,156,157,146,160,150,163,56],{},"Rear passengers ",[129,158,159],{},"80 kg",[129,161,162],{},"3.00 m",[129,164,165],{},"240 kg m",[68,167,168,169,146,172,150,175,56],{},"Fuel ",[129,170,171],{},"110 kg",[129,173,174],{},"2.40 m",[129,176,177],{},"264 kg m",[68,179,180,181,146,184,150,187,56],{},"Baggage ",[129,182,183],{},"20 kg",[129,185,186],{},"3.60 m",[129,188,189],{},"72 kg m",[10,191,192,193,196,197,200],{},"Add the masses: ",[129,194,195],{},"700 + 160 + 80 + 110 + 20 = 1070 kg",". Add the moments: ",[129,198,199],{},"1610 + 328 + 240 + 264 + 72 = 2514 kg m",". Then divide:",[10,202,203],{},[129,204,205],{},"CG = 2514 \u002F 1070 = 2.35 m aft of datum",[10,207,208,209,212,213,216,217,220,221,224],{},"If the published envelope for this loaded mass runs from a forward limit of ",[129,210,211],{},"2.20 m"," to an aft limit of ",[129,214,215],{},"2.45 m",", the CG at ",[129,218,219],{},"2.35 m"," is inside it, and the total mass of ",[129,222,223],{},"1070 kg"," is under the maximum. The aircraft is legal to load this way. Change the baggage or move passengers and you must work it again.",[20,226,228],{"id":227},"what-the-authorities-require","What the authorities require",[10,230,231,232,237,238,243,244,249,250,255],{},"The arithmetic is universal, but the limits and the documentation come from the certification of the aircraft and the operating rules. The CG envelope and mass limits are set when the type is certified, under standards such as ",[37,233,236],{"href":234,"rel":235},"https:\u002F\u002Fwww.easa.europa.eu\u002Fen\u002Fdocument-library\u002Fcertification-specifications\u002Fgroup\u002Fcs-23-normal-utility-aerobatic-and-commuter-aeroplanes",[48],"EASA CS-23"," for smaller aeroplanes and ",[37,239,242],{"href":240,"rel":241},"https:\u002F\u002Fwww.easa.europa.eu\u002Fen\u002Fdocument-library\u002Fcertification-specifications\u002Fgroup\u002Fcs-25-large-aeroplanes",[48],"CS-25"," for large ones, with the FAA's equivalent parts in the United States, and they appear in the approved flight manual. For commercial operations, ",[37,245,248],{"href":246,"rel":247},"https:\u002F\u002Fwww.easa.europa.eu\u002Fen\u002Fdocument-library\u002Feasy-access-rules\u002Feasy-access-rules-air-operations-regulation-eu-no-9652012",[48],"EASA's Air Operations rules"," (CAT.POL.MAB) require the operator to establish the mass and balance of each flight, all under the international standard of ",[37,251,254],{"href":252,"rel":253},"https:\u002F\u002Fstore.icao.int\u002Fen\u002Fannex-6-operation-of-aircraft-part-i-international-commercial-air-transport-aeroplanes",[48],"ICAO Annex 6",". One terminology note: the FAA handbooks speak of \"empty weight\" and \"useful load\", while EASA and ICAO use \"dry operating mass\"; the concepts line up, but keep the framework consistent within one calculation.",[20,257,259],{"id":258},"common-pitfalls","Common pitfalls",[65,261,262,268,274,280],{},[68,263,264,267],{},[28,265,266],{},"Forgetting that fuel shifts the CG."," As fuel burns off, the CG moves, so the aircraft must stay in the envelope at take-off, in the cruise, and at landing, not just at the start.",[68,269,270,273],{},[28,271,272],{},"Using the wrong arm for baggage."," A heavy bag in an aft locker has a long arm and a large moment, and is a common cause of an aft-CG problem.",[68,275,276,279],{},[28,277,278],{},"Assuming \"under max weight\" is enough."," Being within the mass limit says nothing about whether the CG is in the envelope.",[68,281,282,285],{},[28,283,284],{},"Mixing units or frameworks."," Keep to one set of units and one definition of empty mass throughout.",[20,287,289],{"id":288},"in-pilot-efb","In Pilot EFB",[10,291,292,293,296],{},"Pilot EFB does ",[28,294,295],{},"not"," calculate mass and balance, and it is not a certified Electronic Flight Bag. It is a study and planning aid that keeps your weather, NOTAMs, flight time, and logbook in one offline-first place. Work your loading from the approved aircraft flight manual or pilot's operating handbook and your operator's loading procedures, which carry the real arms, limits, and CG envelope for your aircraft. Saved data stays readable offline; pulling fresh data needs a connection.",{"title":298,"searchDepth":299,"depth":299,"links":300},"",2,[301,302,303,304,305,306],{"id":22,"depth":299,"text":23},{"id":59,"depth":299,"text":60},{"id":118,"depth":299,"text":119},{"id":227,"depth":299,"text":228},{"id":258,"depth":299,"text":259},{"id":288,"depth":299,"text":289},"2026-06-03","What datum, arm, moment and centre of gravity mean, how to work a centre-of-gravity calculation step by step, and why staying inside the envelope matters as much as staying under the maximum mass.",false,"md",[312,315,318],{"q":313,"a":314},"What is the centre of gravity and why does it matter?","The centre of gravity is the point at which the aircraft's mass effectively balances. It has to stay within the forward and aft limits the manufacturer publishes, the CG envelope, because a centre of gravity too far forward or aft changes how stable and controllable the aircraft is. The FAA Aircraft Weight and Balance Handbook explains the envelope and its limits.",{"q":316,"a":317},"How do you calculate the centre of gravity?","You multiply each item's mass by its arm, the distance from the datum, to get its moment, add up all the masses and all the moments, then divide the total moment by the total mass. The result is the centre of gravity, expressed as a distance from the datum, which you then check against the published forward and aft limits.",{"q":319,"a":320},"Does Pilot EFB calculate mass and balance?","No. Pilot EFB does not compute mass and balance and is not a certified Electronic Flight Bag. It is a study and planning aid; work your loading from the approved aircraft flight manual or pilot's operating handbook and your operator's loading procedures, which are the source of truth for the figures and limits.",{"name":322,"steps":323},"How to work a mass and balance calculation",[324,325,326,327,328,329,330],"Find the datum, the reference point from which all arms are measured, in the aircraft flight manual.","List every mass item: the basic empty mass, crew, passengers, baggage and fuel, with the arm of each taken from the flight manual.","Multiply each mass by its arm to get that item's moment.","Add the masses to get the total mass, and add the moments to get the total moment.","Divide the total moment by the total mass to find the centre of gravity.","Check the total mass against the maximum limits and the centre of gravity against the forward and aft limits of the CG envelope.","Re-check that the centre of gravity stays within limits as fuel burns off through the flight.",null,{},true,"\u002Flearn\u002Fmass-and-balance-basics",[336,345,353],{"q":337,"options":338,"answer":343,"explanation":344},"What is the centre of gravity (CG) of a loaded aircraft?",[339,340,341,342],"The mass of the aircraft with its standard equipment and unusable fuel","The balance point of the whole loaded aircraft, the total moment divided by the total mass","The horizontal distance from the datum to an item of mass","The reference plane chosen by the manufacturer",1,"The CG is the balance point of the whole loaded aircraft: the total moment divided by the total mass.",{"q":346,"options":347,"answer":299,"explanation":352},"In the worked example, the masses total 1070 kg and the moments total 2514 kg m. What is the resulting centre of gravity?",[348,349,350,351],"2.20 m aft of datum","2.45 m aft of datum","2.35 m aft of datum","2.30 m aft of datum","Dividing the total moment by the total mass gives 2514 \u002F 1070 = 2.35 m aft of datum.",{"q":354,"options":355,"answer":360,"explanation":361},"An aircraft is confirmed to be under its maximum mass. What does this tell you about the centre of gravity?",[356,357,358,359],"Nothing about whether the CG is in the envelope; that must be checked separately","The CG is automatically within the forward and aft limits","The CG no longer needs to be re-checked as fuel burns off","The CG will sit at the datum",0,"Being within the mass limit says nothing about whether the CG is in the envelope; staying under the maximum mass and staying inside the envelope are two separate questions.",{"title":5,"description":308},[364,365,367,369,371,373],{"label":49,"url":46},{"label":366,"url":53},"FAA Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25)",{"label":368,"url":234},"EASA CS-23 (Normal, Utility, Aerobatic and Commuter Aeroplanes)",{"label":370,"url":240},"EASA CS-25 (Large Aeroplanes)",{"label":372,"url":246},"EASA Easy Access Rules for Air Operations (CAT.POL.MAB)",{"label":374,"url":252},"ICAO Annex 6: Operation of Aircraft, Part I","learn\u002Fmass-and-balance-basics","Operations","DXCLDBwwUM_dH8H2Vcya8VBbOlnIMoUFBgjWMLiAUuE",{"related":379,"newer":395,"older":401,"series":331},[380,386,390],{"path":381,"title":382,"description":383,"date":384,"topic":376,"draft":309,"minutes":385,"series":331,"seriesOrder":331},"\u002Flearn\u002Fcold-temperature-altimeter-corrections","Cold-temperature altimeter corrections","Why a pressure altimeter over-reads in cold air, leaving you lower than indicated, and how to correct minimum altitudes for temperature on an approach in mountainous or freezing conditions.","2026-06-21",4,{"path":387,"title":388,"description":389,"date":384,"topic":376,"draft":309,"minutes":385,"series":331,"seriesOrder":331},"\u002Flearn\u002Fmode-s-and-ads-b-explained","Mode S and ADS-B explained","How Mode S adds a 24-bit address, selective interrogation and a data link to the transponder, the difference between elementary and enhanced surveillance, and how ADS-B broadcasts your GPS position.",{"path":391,"title":392,"description":393,"date":384,"topic":376,"draft":309,"minutes":394,"series":331,"seriesOrder":331},"\u002Flearn\u002Fthe-global-reporting-format-for-runway-conditions","The Global Reporting Format for runway conditions","How the Global Reporting Format (GRF) describes a contaminated runway, including the runway condition code (RWYCC) from 6 to 0, the assessment matrix (RCAM), and how the report is split into thirds.",5,{"path":396,"title":397,"description":398,"date":399,"topic":376,"draft":309,"minutes":385,"series":400,"seriesOrder":343},"\u002Flearn\u002Fairspace-classes-explained","Airspace classes explained","The ICAO airspace classes A to G, the service and separation each one provides, and how the US, Europe and the UK implement the same letters differently.","2026-06-04","plan-a-vfr-cross-country",{"path":402,"title":403,"description":404,"date":405,"topic":376,"draft":309,"minutes":385,"series":331,"seriesOrder":331},"\u002Flearn\u002Fdeclared-distances-tora-toda-asda-lda","Declared distances: TORA, TODA, ASDA and LDA","What the four declared distances mean, how clearway and stopway extend them, and why the length of runway you can actually use is rarely just the runway.","2026-06-02",1781989190889]