🧰 Quick tools & cheat sheet play with the numbers

Eleven small calculators for the sums this subject asks for again and again, and a one-screen list of the rules worth knowing by heart.

📋 Cheat sheet — numbers worth knowing

1 Air Information Publications Chapter 1

Before every flight a pilot needs procedures, frequencies, navigation aids, weather services and the airspace to avoid. This chapter is about where that information officially lives.

Three kinds of official information

• 🔺 Changes issued by amendment, supplement or circular are also announced by a trigger NOTAM: valid 15 days after a permanent change, or for the whole of a temporary one.
• 🔤 Types: NOTAMN new · NOTAMR replaces · NOTAMC cancels.
• 🇬🇧 United Kingdom series: international information A–H and J; domestic L–N and R; X exceptionally.
• 🚧 A short-term navaid failure, or a temporary danger area, is a NOTAM (or a supplement if there is time).

The three parts of an AIP

Every contracting State uses the same layout, so the same information is always in the same place.

Location indicators

Four letters: the first two the country, the last two the aerodrome or centre. Add a three-letter agency designator (ZAZ air traffic control unit, ZIZ flight information centre) and a one-letter office designator to address a message.

Aerodrome and weather services

• ⚠️ SIGMETs are prepared by Meteorological Watch Offices; crews are warned for up to 500 NM or 2 hours ahead. At transonic/supersonic levels (FL250–600) moderate turbulence is a SIGMET too.
• 📻 Ask an ATS unit for weather only if it is not available from a broadcast.

Reading navaid entries

• 📡 VORs are aligned with magnetic north at the published variation and year.
• ⭕ DOC "50 NM/50 000 ft": do not use beyond that range or height. A sector may have a larger coverage.
• 🪖 The TACAN channel (e.g. 72X) lets military aircraft get DME range; the DME aerial elevation allows for slant range.
• 🛬 "HO" = available to meet operational requirements; "H24" continuous. "L" = locator, a low-powered NDB.
• 📐 NDB promulgated range: daytime protection limiting bearing error to ±5°; night sky waves not allowed for.
• ✈️ The ILS reference datum is about 50 ft above the threshold, where the glide path passes.

2 Fuel Policy and Fuel Monitoring Chapter 2

How much fuel a commercial flight must carry is set by a common rule; the amounts differ by type, the method never does. Then, once airborne, the crew must keep checking that the plan is still true.

Each part

Fuel monitoring in flight

• 🕒 Check at regular intervals: compare actual and planned use, check enough remains, predict the arrival fuel.
• ⚠️ If expected arrival fuel is below alternate + final reserve, the commander weighs the conditions at destination, en route and at the alternate, and lands with at least final reserve.
• 💻 On a computer plan, REM against each waypoint is the minimum fuel there (often in hundreds of kg: 0043 = 4300 kg). The FMS warns when predicted arrival fuel drops below alternate + final reserve.
• 📈 A "howgozit" plots fuel remaining against distance to go; extrapolate the trend. The slope is steeper in the climb.
• 🔍 Causes of a shortfall: leaks, gauge faults, planning or uplift errors, unforecast headwinds, pound/kilogram and specific-gravity mistakes.

Two special cases

3 Nautical Air Miles Chapter 3

Fuel and time depend on how far the aeroplane flies through the air, not over the ground. Planning tables are therefore written in air miles, and the wind is applied separately.

The time form is the one to use in a climb or descent, where TAS and GS keep changing but the tables give the time and the air distance.

4 Single-engine Piston Aeroplane Chapter 4

The planning single is a retractable monoplane with a constant speed propeller. Four sets of data: climb, cruise power tables, range profile and endurance profile.

Full throttle height is where the throttle is fully open and the selected manifold pressure can no longer be held; above it manifold pressure falls. Shaded table values are about the most the engine can give there.

Using the data

1. Climb graph: time, fuel and NAM from MSL to a pressure altitude at the OAT and mass. Subtract the airfield's figures, then apply the wind to the NAM.
2. Cruise tables: one table per power setting (MP and rpm); TAS, IAS and fuel flow for standard day, ISA +20 and ISA −20. For ISA ±10 interpolate halfway; always interpolate between altitudes.
3. Range profile: still air range in NAM for four power settings, including taxi and run-up, climb, cruise and a 45 min reserve at economy power. Convert to NGM using the TAS shown at 4000, 8000 or 12 000 ft.
4. Endurance profile: a safe endurance, as the 45 min reserve is included. Wind does not change it.

5 Multi-engine Piston Aeroplane Chapter 5

A light twin with counter-rotating constant speed propellers. Climb, range, power, TAS, endurance and descent come on separate sheets.

Rules that differ from the single

• 📈 The climb graph has separate reference lines for time, distance and fuel but one combined scale. Descent works the same way: read the level to MSL, subtract the airfield to MSL.
• 🌡️ Manifold pressure: add 1% per 6°C above ISA, subtract 1% per 6°C below. 30.0 inHg at ISA +12 → 30.6 inHg.
• 🏎️ The power table gives MP, rpm and fuel flow but not TAS — read that from the true airspeed graph.
• 📏 Range with a 45 min reserve at 45% power, or with no reserve: add 1 NM per °C above ISA, subtract 1 NM per °C below. Then convert NAM to NGM.
• ⏳ Endurance the same two ways: safe (with reserve) or total.

6 MRJT Simplified Flight Planning Chapter 6

The planning medium range jet transport (MRJT) is a twin jet. Before the detailed tables come the quick graphs: optimum altitude, short distance cruise altitude, and simplified trip fuel and time.

• 🧳 DOM = ready for the operation, without usable fuel and traffic load: crew and baggage, catering, removable service equipment, water and lavatory chemicals.
• 👥 Traffic load = passengers, baggage and cargo, including non-revenue load. Maximum here: 51 300 − 34 270 = 17 030 kg.
• 🚕 Ramp − take-off mass = 260 kg for APU, start, push-back and taxi.

Which altitude?

Long range cruise gives 99% of the maximum fuel mileage in still air; within 2000 ft of optimum it is close to Mach 0.74.

Simplified trip fuel and time

1. Enter with ground distance; follow the flow lines for the wind (if the wind is off the chart, convert to NAM and ignore the wind lines).
2. Up to the pressure altitude, across to the landing weight reference line, correct for weight, read the fuel.
3. From the upper pressure altitude line, across to the ISA deviation line, read the time.

The charts cover brake release to touchdown with a straight-in approach. Add: APU and taxi, extra flaps-down time, cost index adjustments and reserves.

7 MRJT Detailed Flight Planning Chapter 7

For accurate plans the jet has en route climb tables, integrated range (cruise) tables and descent tables. The cruise tables work on one clever idea: subtraction.

• ⏱️ Climb fuel and time are from brake release; distance from 1500 ft. The tabulated TAS is the climb average, used for NGM = NAM × GS/TAS. A small table corrects fuel for an airfield above MSL.
• 🌡️ TAS: +1 kt per °C above ISA (−1 below). Fuel: the % per 10°C printed under the table. Thrust-limited weights can be ignored.
• 📉 Descent: NGM = NAM ± WC × time/60; +50 kg for engine anti-ice.

8 MRJT Additional Procedures Chapter 8

Twins over oceans, the fuel a failure would need, ferrying with the gear down, carrying cheap fuel, and how to trust (or not) a computer flight plan.

Critical fuel

The worst case is compared with the planned fuel at the critical point; if it is more, load more. The planning graphs assume a 10 000 ft cruise, 250 KIAS descent to 1500 ft, 15 min hold, a missed approach and landing, plus 5% for wind errors; the one-engine graph includes APU fuel. Correct for temperature above ISA and for icing.

Other procedures

• 🗺️ Diversion distance chart: enter speed schedule and weight, choose the approved time, read the distance (still air, ISA). One-engine diversion graph: no pressurisation failure, drift down to the selected level.
• 🛞 Gear-down ferry data: all engines at 220 KIAS, climb and descent included.
• 💶 Tankering: enter with trip NAM, cruise level and landing weight without tankered fuel to get the % of extra fuel burnt carrying it. Worth it only if the destination price is above the break-even price (≈ departure price ÷ (1 − burn%)), and only if the cruise level is not affected.

Computer flight plans

The database holds navaids, waypoints, forecast winds, routes and tracks, fuel policy, aircraft limits and performance, alternates and fuel costs. It needs at least type, departure and destination, cruise mode, traffic load and block time — and garbage in, garbage out.

9 Topographical Chart Chapter 9

Planning a VFR cross-country on a 1:500 000 chart: measuring tracks and distances, decoding symbols, and choosing a level that really clears the ground.

• 🌐 Lambert conformal conic, elevations in feet, co-ordinates in WGS84. Isogonals are valid for a stated year.
• 📐 Measure true track at the mid-point against the nearest meridian (meridians converge). Distance on the meridian scale (1′ latitude = 1 NM) or the NM scale. 1 NM = 1.852 km; 1 m = 3.28 ft.
• 🛬 Aerodromes: four-letter indicator, name, elevation (ft), longest runway (m), tower frequency; (v) = VDF available.
• 🟥 Prohibited (no flight) · restricted (flight under conditions) · danger (dangerous activity at notified times).

Grid MORA

A figure in each half-degree square, read with two noughts added (47 = 4700 ft). It clears terrain by 1000 ft where the highest point is 5000 ft or less, 2000 ft above that. Use it for a quick level, a cross-check, or when unsure of position. For planning, find the highest obstacle within 5 NM either side of track.

Choosing the level

Always the track, not the heading.

Altimeter errors — "high to low, mind how you go"

• 📉 QNH below 1013 hPa: a flight level is lower than its number. About 30 ft per hPa.
• 🥶 Air colder than ISA: the altimeter over-reads — you are lower than indicated (about 4 ft per 1000 ft per °C).
• 🥵 Warmer than ISA: it under-reads — you are higher.

10 Airways Chapter 10

IFR charts — en route, area, departure, arrival and approach — are read fast only if their vocabulary is second nature.

Vertical words

Minimum altitudes on route charts

MAA is the highest usable level. "E" by an arrow: even levels that way (against the semi-circular rule); "O": odd levels on a one-way airway; "PPR": prior permission. "FL80 2700a" = MEA FL80, route MORA 2700 ft.

Airspace classes

A–E are controlled airspace. In the United Kingdom airways are 5 NM either side of the centreline, lower routes end at FL245, upper routes (prefix U) run FL245–FL460, and advisory routes (suffix D) are class F.

Speeds and holding

• 🐢 250 kt IAS below FL100 unless cleared; on arrivals, maximum speed from 3 min before the holding fix or the SLP (speed limiting point).
• 🔁 Holding: above FL140 to FL200 240 kt, to FL340 265 kt, above M0.83; turbulence 280 kt or M0.8, whichever less. D9 = outbound leg ends at 9 NM; MHA = minimum holding altitude.
• 🧭 Chart courses are magnetic unless marked T or G. MSA: 1000 ft clearance within 25 NM, emergency use.

Approach categories by 1.3 VS0: A < 91 · B 91–120 · C 121–140 · D 141–165 · E 166–210 kt.

11 Airways — Miscellaneous Charts Chapter 11

Polar and oceanic charts: where magnetic north stops being useful, where grid north takes over, and how the North Atlantic is planned.

The charts

Oceanic requirements

• 📏 RVSM: two independent altimetry systems, automatic altitude control, altitude alerter (Mode C in transition airspace). Primary altimeters within ±200 ft. Flight plan item 10: W.
• 🛰️ MNPS: two long range navigation systems, each showing position relative to track continuously. Item 10: X.
• ⏱️ The Mach number technique uses true Mach number. HF: higher frequencies by day, lower by night.

12 ATC Flight Plan Chapter 12

The flight plan is advance notice of a flight — route, level, speed and who is on board — in a fixed format so that every unit can read it.

Filing and changing it

• 🕐 File at the departure reporting office normally ≥ 60 min before EOBT (3 h for flights under air traffic flow management). EOBT 1540 → file by 1440, not by take-off − 60.
• ⏳ Delay of 30 min past EOBT (controlled) or 1 h (uncontrolled): amend, or cancel and refile.
• 📡 Filed in flight: to the station serving the unit for the airspace; wait for a clearance (or acknowledgement for advisory service).
• ✅ The first ATS unit receiving it checks format, completeness and accuracy and confirms acceptance.
• 📣 Report TAS changes of 5% or more and estimate changes of more than 3 min. Landing elsewhere: tell the destination unit within 30 min of the ETA there.

The items

Item 15 grammar

• 🧩 Off-airway start: DCT joining point, then the route. No DCT between two co-ordinate or bearing/distance points.
• 📍 Only points of change; each followed by the next route (even if the same) or DCT. A same-direction lower/upper transition needs no point.
• 🌍 Off-route points ≤ 30 min or 200 NM apart; east–west at 10° longitude (20° beyond 70°), north–south at 5° latitude.

Repetitive flight plans

• 🔁 IFR only, same days of consecutive weeks on ≥ 10 occasions or daily for ≥ 10 days, highly stable, whole flight, all authorities agreeing.
• 📅 Permanent changes ≥ 7 days ahead; temporary type, speed or level changes ≥ 30 min before departure (a level change alone may be given by radio).
• ❌ A changed identification, departure, route or destination for one day: cancel the RPL that day and file an individual plan. Delay ≥ 30 min: tell the departure unit at once.
• 📋 Listing: assumed IFR, scheduled, Mode A/C; sorted by departure indicator then EOBT; item K Monday = 1, 0 = no flight; − delete, + add; UFN.

13 Point of Equal Time Chapter 13

If something goes wrong over the sea, which way is quicker — back or on? The point of equal time (also called the critical point or equal time point) answers that before the flight.

14 Point of Safe Return Chapter 14

To an island with no alternate, the only fall-back is to turn round. The point of safe return (formerly the point of no return) is the furthest you can go and still get back with the reserves intact.