Monitor fuel as a prediction of landing options

Why compare fuel at regular checkpoints?

A trend reveals whether the remaining plan still has the quantities and options it assumes.

Record comparable quantities

At a checkpoint, compare actual fuel with planned fuel at that same point and phase. Calculate fuel used from a consistent previous reading, accounting for any relevant documented transfers or system conventions. A difference between tank indications is not automatically engine consumption.

Actual average flow equals fuel used divided by elapsed hours. Compare it with a representative planned flow for that phase. A higher quantity used can come from a longer time, a higher flow or both. Separating those causes prevents a wind-induced delay from being mistaken for an engine consumption fault.

Predict the landing state

Estimate remaining trip fuel using the updated route, wind, speed, level, aircraft configuration and appropriate performance data. Predicted destination fuel = current usable fuel minus revised remaining consumption. Compare the result with the quantities required to preserve the intended landing options under the applicable scheme.

If a significant discrepancy appears, investigate it and use the applicable aircraft procedures. A leak, imbalance, indication issue or unexpectedly high burn is not adequately addressed by merely typing a new flow into a planning calculator. The calculation supports a decision; it does not replace aircraft diagnosis or checklist action.

Use trend and uncertainty

A single reading can have measurement uncertainty, but a consistent adverse trend deserves attention before the planned margin is exhausted. Record the facts and revise estimates through the operator’s required process. Do not wait for the final reserve quantity to appear on the gauge before assessing a deteriorating plan.

The laboratory uses constant remaining flow and GS to isolate a fuel prediction. It separately shows current fuel, remaining burn and protected landing quantity. The exercise teaches the arithmetic and early comparison, while actual in-flight management requires the current rule, approved procedures and the nearest suitable safe-landing options.

What separates MINIMUM FUEL from a fuel emergency?

The declaration follows predicted landing protection and the remaining landing options.

Use the current aeroplane rule

Under the cited CAT.OP.MPA.185 framework,MINIMUM FUEL applies after commitment to a specific aerodrome when a change to the existing clearance may cause landing below planned final reserve. A fuel emergency requires the initial transmission MAYDAY MAYDAY MAYDAY FUEL when predicted usable fuel at the nearest aerodrome where a safe landing can be made is below planned final reserve.

These are different conditions. A minimum-fuel declaration does not itself mean emergency priority, and it is not a routine request for favourable routing. The emergency criterion is predictive: waiting until the fuel physically on board falls below the reserve can be far too late. SERA.11012, read with SERA.14095, combines the distress signal, preferably repeated three times, with the distress nature FUEL; CAT.OP.MPA.185(d) expressly gives the triple-MAYDAY fuel form. Sources were checked on 23 October 2026 against Air Operations Revision 24 and SERA August 2025.

Predict with a safe-landing option

Use an honest current estimate for the nearest aerodrome where a safe landing can be made, considering weather, aircraft condition and the actual route/clearance. A geographically nearer runway that cannot support a safe landing is not made suitable by a favourable distance number.

When the existing destination plan becomes unsupportable, assess and act under the current procedures. Do not continue an avoidable deterioration merely because an earlier plan carried enough fuel. Communicate the relevant state clearly using the prescribed phraseology and operational process.

Keep the demonstration limited

The laboratory compares predicted landing fuel with a stated protected threshold for one synthetic option. It does not determine that an aerodrome is safe, assess commitment to an existing clearance or issue an operational declaration. Those facts are required to apply the rule correctly.

For the exercise, a predicted nearest-safe landing quantity 900 kg against planned final reserve 1,000 kg is 100 kg below that threshold. That numerical fact supports the stated emergency criterion when the scenario’s nearest-safe-aerodrome facts are established. A different number above reserve does not automatically establish every MINIMUM FUEL condition; the commitment and clearance-change assessment still matters.

Can you explain and apply the mechanism?

Four original questions. Work from the stated facts, then compare your reasoning with the explanation.