Aviation standard operating procedures explained: learn how pilots use flows and checklists, and handle interruptions, mismatches and emergencies.
In aviation, standard operating procedures (SOPs) are an operator's documented, repeatable methods for normal, abnormal and emergency operations. Pilots use flows to configure or inspect the aircraft, then checklists to verify critical items. The checklist supports the procedure; it does not replace aircraft knowledge, judgement or crew communication.
SOPs, flows and checklists are different tools
An SOP defines the whole standard method, while a flow accomplishes actions and a checklist confirms or directs selected safety-critical items.
| Tool | Purpose | Typical content |
|---|---|---|
| SOP | Defines how an operation is conducted | Crew duties, callouts, automation policy, operating limits, briefings, decision gates and checklist triggers |
| Flow | Accomplishes a group of actions efficiently | A memorised visual or physical scan of controls, displays and systems |
| Checklist | Verifies essential actions or directs them in order | Short challenges, required responses and configuration checks |
| QRH | Provides non-normal and emergency procedures | Condition-specific checklists, cautions, limitations and follow-up actions |
A normal checklist is deliberately shorter than the complete procedure. If it listed every switch movement and routine action, critical checks would be buried and pilots would spend too long looking inside the cockpit. A mistake we see repeatedly in simulation is treating the checklist as the complete operating manual.
Are SOPs the same for every airline and aircraft?
No. SOPs and checklist responses vary by aircraft type, variant, operator, training organisation and jurisdiction, even when crews are flying similar equipment.
The controlled documents applicable to that aircraft and operation take precedence. An SOP cannot override the law, an aircraft flight manual or pilot's operating handbook limitation, or an applicable approved procedure. Manufacturer guidance may also be adapted into an operator's own task sharing and callouts.
General aviation pilots normally work from the exact aircraft's POH or AFM, approved supplements and any flying-school or club procedures. Our aircraft-specific Cessna 172 operating example shows why a generic checklist cannot replace the documentation carried for the aeroplane.
Mixing procedures is risky. A checklist copied from another airline, aircraft variant or simulator add-on may assume different equipment, crew roles or preceding actions.
How do pilots use a normal checklist?
Pilots use normal checklists at defined trigger points and follow the challenge-and-response or read-and-do method specified by their SOP.
On a two-pilot flight deck, the pilot flying maintains the flight path while the pilot monitoring commonly reads the checklist, although exact duties vary. A single pilot first establishes a safe flight path and manageable workload before looking down at a printed or electronic checklist.
- Reach the checklist trigger. The SOP specifies when the checklist begins, such as after a flow, before movement or after a particular phase has been completed.
- Complete the required flow. The assigned pilot performs the normal actions using the prescribed scan pattern rather than guessing from habit.
- Select the correct checklist. It must match the aircraft, variant, phase of flight and controlled revision.
- Read and verify each item. The reader states the challenge, and the responsible pilot checks the actual control, indication or condition before giving the specified response.
- Stop on an incorrect response. The crew corrects the condition and repeats the item. Pilots must never answer according to what a switch should show or what they intended to do.
- Close the checklist explicitly. The reader confirms completion so both pilots share the same understanding of the aircraft's state.
An approach SOP, for example, covers briefing duties, automation use, configuration planning, stabilisation criteria and the trigger for the landing checklist. The checklist verifies selected critical conditions; it does not teach or contain the whole approach procedure.
Why the flow usually comes before the checklist
A flow completes the routine actions efficiently, and the subsequent checklist catches omissions or incorrect settings.
This flow-then-check method is common in airline normal operations, as illustrated by our phase-by-phase A320 flow and checklist example. It is not universal: some procedures use the checklist as a read-and-do list, so pilots follow the published method rather than imposing a flow from another operator.
Do pilots memorise checklists?
Pilots normally memorise flows, standard callouts and only those emergency actions explicitly designated as memory items; they still read the actual checklist.
Memory items exist where delaying action to find a document could make the situation worse. Once the aircraft is under control and the immediate actions are complete, the crew opens the appropriate non-normal checklist or QRH, confirms the condition and continues methodically. Our explanation of how QRH and memory actions work together covers that process in more detail.
Electronic checklists may sense certain switch positions automatically, but they do not remove the need for verification. A displayed tick cannot assess every physical condition or crew judgement item, and the SOP specifies an approved backup if the electronic system becomes unavailable.
What should pilots do after an interruption or mismatch?
After an interruption, pilots verbally hold the checklist, preserve their place and resume according to the SOP; if their position is uncertain, they restart from a defined point or from the beginning.
- Interrupted checklist: identify the last positively completed item rather than relying on memory. Restart when doubt remains.
- Incorrect response: stop the checklist, inspect the actual control or indication, correct the discrepancy and repeat the challenge.
- Wrong checklist or variant: do not force the aircraft to match it. Confirm the document, aircraft configuration and procedure source.
- Excessive heads-down time: pause checklist work until the flight path and workload permit it. Aircraft control takes priority.
- Conditional or inapplicable item: follow the published branch or response. Do not casually invent an “N/A” response.
SOPs are the operational default, not a substitute for judgement. Where immediate safety requires a deviation, the pilot in command uses only the deviation necessary, stabilises the situation and returns to the approved procedure when possible. The precise authority and reporting requirements depend on the jurisdiction and operation.
Practising SOP discipline in a flight simulator
Flight simulation is most useful when the aircraft model, operator-style procedure and checklist all match.
Use the documentation supplied for the aircraft or add-on, assign pilot-flying and pilot-monitoring duties even when practising alone, and say challenges and responses aloud. Pause while learning the flow, then practise without pausing and deliberately rehearse how to recover from an interruption.
Community-made and simulator checklists are useful learning aids, but they are not operational authority for a real aircraft. Never carry a simulator checklist into real-world flying unless it is the controlled, approved document applicable to that aircraft and operation.