FAA ADX common mistakes
FAA ADX · Understand the traps and how to avoid them.
Computing a dispatcher's legal rest by counting backwards from the flight's arrival (block-in) time rather than from the end of the duty period, then approving a release that puts the dispatcher inside the required rest window.
Candidates study the duty-limit numbers in isolation and memorize '10 hours' without anchoring it to a definition of when the duty period actually ends, so they instinctively anchor on the most visible time on the release - the arrival time.
What to do instead
For every duty-limit question, draw a three-line timeline: duty-on, duty-off (including any post-flight administrative or handover time), and next duty-on. Compute rest as next duty-on minus duty-off, and only then compare to the limit. Never let a flight time substitute for a duty time in the calculation.
Applying the standard 600-2 / 800-2 alternate weather minimums to every alternate airport instead of checking whether that specific airport publishes non-standard alternate minimums.
The standard values are taught first and are easy to apply universally; the non-standard alternate minimums section is buried at the front of the terminal procedures volume and is skipped under time pressure.
What to do instead
Make 'check the alternate minimums listing for the named alternate' a mandatory step before any alternate-weather computation. If a non-standard minimum is published, it governs and may be higher or require a specific approach procedure; state the source of the minimum in your work so the reasoning is auditable.
Deciding an alternate is not required based only on the destination forecast, ignoring whether the destination has a usable instrument approach procedure for the expected approach.
Candidates memorize the '1-2-3' ceiling-and-visibility window but drop the precondition that the rule only relieves the alternate requirement when an approved instrument approach is available at the destination.
What to do instead
Answer in two steps: (1) does the destination have a usable IAP for the planned approach? If no, an alternate is always required regardless of forecast. Only if yes, (2) apply the ceiling and visibility window from one hour before to one hour after the estimated time of arrival.
Building the fuel plan with the reserve computed at holding speed or at an arbitrary figure, and failing to recompute the reserve when the planned cruise altitude or routing changes.
Reserve fuel is treated as a fixed number to be copied from a previous problem rather than a value derived from the final cruise profile, so a late change to altitude or route invalidates the whole total without the candidate noticing.
What to do instead
Compute the reserve last, at the normal cruising speed and altitude actually planned, after the trip fuel and route are frozen. If any input to the cruise profile changes, restart the fuel block rather than patching one line of it.
Reading a TEMPO or PROB group in a TAF as the prevailing forecast condition and dispatching against it, or using a TAF outside its stated valid period.
The prevailing group appears first and reads as 'the' forecast; temporary and probability groups look like ordinary lines of text, so their conditional nature is lost when the candidate is scanning for a ceiling or visibility number.
What to do instead
Before extracting any value from a TAF, classify each group: prevailing (valid for the whole period from its start), FM (prevailing from that time forward), TEMPO (temporary fluctuation, not prevailing), PROB (probability, not prevailing). Extract ceilings and visibilities only from prevailing groups, and confirm the ETA plus the alternate window falls entirely inside the valid period.
Confusing the three turbine-engine temperature limits - using the maximum allowable temperature as the assumed temperature for a reduced-thrust takeoff, or using the flat-rated limit where a derate applies.
All three limits appear as similar-looking temperatures on the same page and are taught together, so the distinct roles (structural limit, thrust-setting limit, and reduced-thrust input) blur into 'the hottest number'.
What to do instead
Attach a one-phrase job description to each limit and recite it before answering: the maximum limit is the never-exceed structural value, the flat-rated limit bounds where thrust stays constant, and the assumed temperature is an input used to obtain a lower thrust setting and must stay below the maximum. If the question asks for a takeoff setting, first identify which role the number plays.
Treating MEA, MOCA, and off-route obstruction clearance altitudes as interchangeable, and assuming a published minimum en route altitude guarantees terrain clearance everywhere along the airway at night.
The altitudes are all printed near the same airway and differ only by a letter, and candidates memorize 'MEA clears terrain' without attaching the signal-coverage requirement or the segment limits of the MOCA.
What to do instead
Learn each by what it guarantees and over what distance: MEA guarantees obstacle clearance and navigation signal reception along the whole segment; MOCA guarantees obstacle clearance only, and only within a defined distance from the navigation facility; off-route altitudes apply only in the designated area. On any question, name the guarantee being asked about before selecting a number.
Clearing a flight under an MEL item without applying the operational and maintenance procedures attached to that item, treating the dispatch relief as automatic once the item number is found.
The MEL is scanned as a lookup table of 'can we go?' answers, and the (O) and (M) annotations are small parenthetical marks that read as footnotes rather than as conditions of dispatch.
What to do instead
Treat every MEL entry as a three-part test: the item number and installed quantity, the operational procedure conditions, and the maintenance procedure conditions. Write out the conditions explicitly on the release or the candidate's scratch work, and if a condition cannot be met, the item is not dispatchable - the entry does not apply.
Describing the dispatcher's emergency role as advisory only, or shifting the entire decision to the pilot in command, when asked who may declare an emergency or deviate from the regulations.
The regulatory text is written around the pilot in command's emergency authority, so candidates over-read it and conclude the dispatcher has no independent authority, missing the shared operational control concept the question is testing.
What to do instead
State both halves of the answer: the pilot in command has emergency authority to deviate to the extent required, and the dispatcher shares operational control and may exercise emergency authority, including declaring an emergency, when the situation requires it. Answer questions about operational control by naming both parties and the shared nature of the authority.
Applying a full headwind or tailwind component from the forecast to a takeoff or landing distance instead of using the required conservative fraction of the headwind and the full tailwind penalty.
The wind component is computed once and carried straight into the performance chart, because the asymmetric treatment of headwind versus tailwind feels like an arbitrary rule rather than a safety margin against wind loss during the takeoff or landing roll.
What to do instead
Before entering any performance chart, write the rule next to the wind number: use only the required fraction of the reported headwind (never more than half) and the full tailwind component. Also verify the wind is from the runway in use and note the runway slope, since a wrong sign on slope can cancel the wind correction and hide the error.