Decoding the OFP and Loadsheet: A Pilot's Field Guide
Updated: Aug 16
Every flight starts with two documents that are almost entirely made of abbreviations. The operational flight plan tells you how the flight is supposed to go. The loadsheet tells you what you are actually carrying and whether the aeroplane is legal to fly.
Between them they hold perhaps two hundred acronyms, and most pilots learn maybe forty of them properly during type conversion and pick up the rest by osmosis. That works until it does not. The gaps show up on a line check, during a diversion when someone asks what your extra fuel was actually for, or on a heavy day when the underload figure is the only number standing between you and offloading bags.
This is the OFP and loadsheet reference nobody hands you. It is written for airline pilots, but the structure is deliberately generic. Formats vary between operators and flight planning systems, so treat your own company documentation as the authority.
Part one: reading the OFP
The header block
The top of the plan establishes identity and the basic geometry of the flight.
FLT or FLTNO, the flight number. REG is the aircraft registration and TYPE the aircraft type.
STD and STA, scheduled times of departure and arrival. ETD and ETA are the estimated equivalents.
ETOT and ELDT, estimated take-off and landing time. These, not the scheduled times, drive slot compliance and performance calculations.
ATC CALLSIGN, what you use on the radio, which is not always the flight number.
ALTN, the destination alternates, usually two. ERA covers en-route alternates and TKOF ALTN a take-off alternate.
The route string
The route appears as an ATC-filed string, then again as a waypoint-by-waypoint breakdown. SID and STAR are the departure and arrival procedures, DCT means direct between two points, and airway identifiers sit between waypoints. In the waypoint table you will typically find:
MC or TC, magnetic or true course for that leg
DIST and CUM DIST, leg and cumulative distance
FL, planned flight level for the segment
TAS and GS, true airspeed and groundspeed
WIND or W/V, forecast wind for the segment
COMP, wind component, positive for tailwind and negative for headwind
ISA DEV or DISA, deviation from standard atmosphere temperature
SAT or OAT, static or outside air temperature
TROP, tropopause height
ETO and ATO, estimated and actual time overhead
EFOB, estimated fuel on board at that point
MORA, minimum off-route altitude, and MSA, minimum sector altitude
The EFOB column is the one to keep your thumb on. Comparing actual fuel against EFOB at each waypoint is the fastest in-flight check on whether the plan is still valid.
The fuel breakdown
This is the section most often misread, because the labels look similar and the legal weight of each is very different.
TAXI, fuel for APU and engine running before take-off. Not part of take-off fuel.
TRIP or TIF, fuel from take-off at departure to landing at destination.
CONT, contingency fuel, held against unforeseen deviations such as a lower level, a different routing or degraded winds. Under EASA rules commonly 5% of trip fuel, reducible to 3% with a suitable en-route alternate.
ALTN, fuel to fly a missed approach, transit to the alternate, and land there.
FINRES, final reserve. For turbine aircraft, 30 minutes holding at 1,500 feet above the alternate elevation in ISA.
ADDL, additional fuel for a specific regulatory requirement, such as an isolated aerodrome or ETOPS critical fuel.
EXTRA or DISCR, captain's discretionary fuel.
BLOCK or RAMP, everything: taxi plus take-off fuel. TOF is block minus taxi.
BURN-OFF, trip fuel as a weight reduction, used when working back from a landing weight limit.
Three of those deserve emphasis. Contingency is not a discretionary buffer and it is not fuel for a known holding requirement. Final reserve is the hard floor: arriving with less is a mayday rather than a discussion. And confusing block with take-off fuel is the most common fuel error on the flight deck, which always goes the wrong way.
Performance and economics
CI, the cost index, the ratio between the cost of time and the cost of fuel. Zero gives maximum range; a high value gives minimum time. It is not a speed, it is an economic instruction the FMS converts into one.
OPT FL, optimum flight level for weight and conditions. MAX FL is the maximum available, usually buffet or thrust limited.
ZFW, TOW and LDW, which appear here as planned figures and again on the loadsheet as actual ones. Only the loadsheet figures are operational.
Oceanic, remote and ETOPS entries
EEP and EXP, the ETOPS entry and exit points.
ETP, the equal time point between two diversion airfields.
CP, critical point, and PNR, point of no return.
RCF, reduced contingency fuel, where a decision point en route allows a lower initial uplift.
NAT entries, OTS tracks and SELCAL codes on oceanic plans, with RVSM and PBCS annotations.
Part two: reading the loadsheet
The OFP is a forecast. The loadsheet is a statement of fact about the aeroplane as it sits on stand, and it is the document that makes the flight legal.
The weight chain
DOW, dry operating weight: the aeroplane ready for service with crew and catering but no payload and no usable fuel. DOI is the matching index used for trim.
PAYLOAD, passengers, baggage, cargo and mail.
ZFW, zero fuel weight, is DOW plus payload. MZFW is the structural maximum, which exists because fuel in the wings relieves wing bending moment. Payload does not.
TOF, take-off fuel. TOW is ZFW plus take-off fuel. MTOW may be structural or performance-limited on the day.
LAW or LDW, landing weight, is TOW minus trip fuel. MLW is the maximum.
Four limits apply simultaneously: MZFW, MTOW, MLW, and the regulated take-off weight for the runway and conditions. The LIM field tells you which one bites first.
Underload
UNDERLOAD is the margin between your actual weight and the most limiting of those maxima. It tells you how much more you could take before something has to come off, and how much slack you have for a last minute change. Read it before the ground staff ask, not after.
Passenger and cargo distribution
Passengers appear as a distribution across cabin zones, written as figures separated by slashes.
The total appears as PAX or TTL, often split as M/F/C/I for male, female, child and infant, because standard weights differ.
Cargo appears by hold position, fore to aft, with BULK for the loose-loaded compartment and ULD identifiers for containers.
Trim and balance
MAC, the mean aerodynamic chord. Centre of gravity is expressed as a percentage of it.
MACZFW, centre of gravity at zero fuel weight, and MACTOW, centre of gravity at take-off weight. LIZFW and LITOW are the corresponding index figures.
THS or STAB, the resulting stabiliser trim setting, which is what gets entered before departure.
BALLAST, where fuel or freight is carried purely to keep the centre of gravity inside limits.
The stabiliser setting is the number that kills people when it is wrong, and it is the reason the loadsheet gets a cross-check rather than a glance.
Last minute changes
LMC is a last minute change, applied after the loadsheet is issued. Each operator sets a tolerance, and the LMC is only valid if the revised weights stay inside every limit and inside the trim envelope. The discipline here is simple and frequently ignored: an LMC that consumes your entire underload is not an LMC, it is a new loadsheet.
SI is supplementary information, carrying anything that does not fit the standard fields. Read it. Special loads, dangerous goods notifications and crew changes live there.
OFP and loadsheet traps worth knowing
Block versus take-off fuel. Block includes taxi. Performance calculations do not.
Contingency is not discretionary. Fuel for a known holding delay is extra fuel, not borrowed contingency.
The planned ZFW is not the actual ZFW. The OFP figure is an estimate produced hours earlier.
Standard passenger weights are averages. Sound across a full cabin, unreliable on lightly loaded sectors.
Landing weight can be the binding limit. On a short sector with heavy payload, MLW rather than MTOW often constrains you.
Why any of this belongs in your logbook
Wader has an OFP import on the flight log screen. Point it at the PDF and the route and aircraft details load straight into the entry, without retyping any of it.
Where the plan lists alternates, they are added to the Alternates tab automatically. One pull to refresh then updates the weather for the entire route, destination and alternates together, instead of checking each aerodrome by hand.
Formats and terminology vary between operators, flight planning providers and regulatory authorities. Your company operations manual is always the governing reference.
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