Which Cause Gets Recorded When a Ground Hold Delays the Next Flight's Departure

Two Fifteen-Minute Clocks That Do Not Measure the Same Thing

Federal aviation records carry two counters that both trip at fifteen minutes. They do not count the same event, which is why one afternoon of congestion leaves two different paper trails.

The first belongs to the Federal Aviation Administration. Its reporting definition in FAA Aviation System Performance Metrics, OPSNET: Delays requires that "Delays to instrument flight rules (IFR) traffic of 15 minutes or more, which result from the ATC system detaining an aircraft at the gate, short of the runway, on the runway, on a taxiway, or in a holding configuration anywhere en route, must be reported." Every element is load-bearing: the traffic must be under instrument flight rules, the detention must come from the control system, and the clock must reach fifteen minutes. A twelve-minute hold is not an OPSNET delay.

The second belongs to the Department of Transportation's reporting rule, eCFR, 14 CFR Part 234, Airline Service Quality Performance Reports. Under section 234.2, a late flight means "a flight that arrives at the gate 15 minutes or more after its published arrival time." The paired definition of on-time in the same section draws its line just short of that mark, and it does not repeat the word gate. Neither definition mentions air traffic control, weather, or any cause. The test is the arrival against the schedule the carrier published.

The FAA counter asks what the control system did to an aircraft. The reporting rule asks how the arrival compared with a schedule. An aircraft held eighteen minutes by traffic management can still reach the gate early if the published block time absorbs the hold, making it a delay in one federal record and an on-time arrival in the other. The choice of where a clock starts decides what the record can later show, a problem traced in Measuring an Ambulance Response From Dispatch, Not From the Moment Someone Dials.

The Chain

What follows is a sequence of records, not a claim about how any day unfolds. Each step names the provision that governs it.

  1. A capacity constraint becomes a ground hold. FAA Order JO 7210.3, Facility Operation and Administration, Chapter 17 Section 9 describes the tool at paragraph 17-9-2: "A GDP is a TM process administered by the ATCSCC; when aircraft are held on the ground in order to manage capacity and demand at a specific location, by assigning arrival slots." The aircraft waits at its origin instead of over its destination.
  2. The hold is recorded only above the threshold. The OPSNET definition above requires fifteen minutes of ATC-caused detention before the delay is reportable. Shorter holds leave no entry in that dataset.
  3. The aircraft arrives late at the gate. Fifteen minutes or more past the published arrival time makes the flight late under 14 CFR 234.2, measured at the gate.
  4. The same airframe is scheduled to fly again. The next flight cannot push back until the aircraft is there and turned.
  5. The second flight is coded to a category that names no cause. Section 234.4(a)(21) requires the carrier to report "Minutes of delay attributed to a previous late arriving aircraft, if any." BTS defines that category as "A previous flight with same aircraft arrived late, causing the present flight to depart late." It records that something happened earlier, not what.
  6. The crew's own clock keeps running. A flight duty period, under 14 CFR 117.3, "begins when a flightcrew member is required to report for duty with the intention of conducting a flight, a series of flights, or positioning or ferrying flights, and ends when the aircraft is parked after the last flight and there is no intention for further aircraft movement by the same flightcrew member." Ground time waiting for an inbound aircraft falls inside that window.
  7. The flight cancels, and leaves the delay table. A cancelled flight is defined in 14 CFR 234.2 as "a flight operation that was not operated, but was listed in a carrier's computer reservation system within seven calendar days of the scheduled departure." It is no longer a late flight.
From ground hold to cancellation: which record holds the cause at each step Seven numbered steps. A ground delay program holds an aircraft; the hold enters the FAA Operations Network only at fifteen minutes or more; the arrival is late under 14 CFR 234.2 at fifteen minutes or more at the gate; the next flight by the same aircraft is coded to the late arriving aircraft category, which names no underlying cause; the crew flight duty period continues; the flight cancels and is no longer a late flight. The chart shows the order of the records, not the frequency of any outcome. Seven steps, four record systems, one cause that stops travelling Each step cites the provision that governs it. Order of records only; no frequency is implied. 1 Ground delay program holds the aircraft at its origin FAA Order JO 7210.3, paragraph 17-9-2. Aircraft held on the ground; arrival slots assigned. 2 Hold enters the FAA record only at 15 minutes or more OPSNET counts ATC-caused detention of IFR traffic at or above that threshold. 3 Arrival is late at 15 minutes or more, measured at the gate 14 CFR 234.2. The test is the published arrival time, not the cause. 4 The same airframe is scheduled to fly again The next departure waits for the aircraft and the turn. 5 Coded to late arriving aircraft, a category that names no cause 14 CFR 234.4(a)(21). BTS states airlines do not report the causes of the late-arriving aircraft. 6 The crew flight duty period keeps running through the wait 14 CFR 117.13 and Table B. Scheduled maxima printed in that table run from 9 to 14 hours. 7 Cancellation is recorded, but no longer as a late arrival 14 CFR 234.2 defines a cancelled flight by the seven-calendar-day listing rule. Sources: FAA Order JO 7210.3; FAA OPSNET delay definition; 14 CFR 234.2, 234.4, 117.13.

The Five Fields and the Floor Beneath Them

Section 234.4 requires each reporting carrier to file BTS Form 234 monthly, listing numbered data elements for every reportable flight. Five of those elements are causal minute fields: minutes attributed to the air carrier, to extreme weather, to the national aviation system, to security, and, in item (21), to a previous late arriving aircraft. Four of the five name something that happened to this flight. The fifth names something that happened to a different flight.

Two thresholds decide whether any of those fields is filled in. Paragraph (j) states, in full: "When reporting causal codes in paragraph (a) of this section, reporting carriers are required to code delays only when the arrival delay is 15 minutes or greater; and reporting carriers must report each causal component of the reportable delay when the causal component is 5 minutes or greater." The Bureau of Transportation Statistics restates the lower floor in operating language in Technical Directive No. 40, effective January 1, 2026: "For all late flights, you account for the cause and length of departure delays of 5 minutes or longer (with the exception of No. 5 below)." Note that the directive phrases that floor as departure delays while the regulation phrases it as causal components of the reportable arrival delay; the two texts are not word for word the same.

An arrival 14 minutes past the published time is not a late flight, so no causal code is required. An arrival 16 minutes past it must be coded, and if that 16 minutes accumulated as four separate 4-minute components, none reaches the 5-minute floor at which the rule requires each component to be reported. The total is still accounted for: Technical Directive No. 40 instructs that "Reported delay minutes must equal the arrival delay."

A 14-minute arrival and a 16-minute arrival under the two reporting thresholds Left panel: an arrival 14 minutes past the published time falls below the 15-minute coding threshold, so no causal code is required. Right panel: an arrival 16 minutes past the published time is above the threshold and must be coded, and four components of 4 minutes each fall below the 5-minute floor at which the regulation requires each causal component to be reported, while Technical Directive No. 40 still requires reported delay minutes to equal the arrival delay. Both panels are illustrations of how the two thresholds in 14 CFR 234.4(j) interact, not observations of any flight. A ceiling at 15 minutes, a floor at 5 minutes, and the gap between them Illustration of 14 CFR 234.4(j). Not an observation of any flight. Arrival 14 minutes past published time 14 minutes 15 min Below the coding threshold. The flight is not late under 14 CFR 234.2, and no causal code is required for it. Causal fields filled: none required The delay exists. The record of its cause does not. Arrival 16 minutes past published time 4 min 4 min 4 min 4 min = 16 min Above the coding threshold, so the delay must be coded. Each component is 4 minutes, below the 5-minute floor for reporting components. Components reaching the 5-minute floor: none Technical Directive No. 40 still requires reported delay minutes to equal the arrival delay. Source: 14 CFR 234.4(j); BTS Technical Directive No. 40, effective January 1, 2026.

Where the Cause Goes at the Turn

The late arriving aircraft field is where information stops being carried forward. Bureau of Transportation Statistics, Understanding the Reporting of Causes of Flight Delays and Cancellations states it plainly: "Airlines do not report the causes of the late-arriving aircraft but an allocation can be made using the proportion of weather related-delays and total flights in the other categories." The second half matters as much as the first: the cause is not in the filing, and anyone who wants it must estimate it from the other categories.

BTS Technical Directive No. 40, Reporting On-Time Performance supplies the arithmetic the field is supposed to contain. It defines the category as a previous flight with the same aircraft arriving late and causing the present flight to depart late, then adds a ceiling: "The minutes assigned to Late Arriving Aircraft can never be more than the delay time of the previous flight." The formula it gives is "Minutes attributed to a Late Arriving Flight = Arrival time of previous flight + Scheduled turn time – Scheduled Departure time." It also carries an exception that belongs with the rule: "Exception from the same aircraft rule is allowed when carrier substitutes an aircraft for a delayed aircraft in order to decrease the delay of upcoming flights."

Weather shows how much a five-field scheme can absorb. The extreme weather category covers "Significant meteorological conditions (actual or forecasted) that, in the judgment of the carrier, delays or prevents the operation of a flight such as tornado, blizzard or hurricane." The agency also writes that "There is another category of weather within the NAS category. This type of weather slows the operations of the system but does not prevent flying." So weather appears in two of the five causal fields: extreme weather in field (18) and non-extreme weather inside the national aviation system field (19). A third field, late arriving aircraft in item (21), carries whatever share of the earlier flight's weather delay propagated forward, and reports none of it as weather. Counting only field (18) understates the weather contribution by construction.

The same shape appears when a classification moves while the object underneath it does not, the mechanism described in When Downstream Development Arrives, a Dam's Hazard Class Moves and Its Condition Does Not. Here the label moves from flight to flight while the underlying condition goes unnamed in the second filing.

The Crew Clock Does Not Reset at the Gate

Underneath the delay record runs a limit indifferent to which causal field was ticked. Section 117.13 reads: "Except as provided for in § 117.15, no certificate holder may assign and no flightcrew member may accept an assignment for an unaugmented flight operation if the scheduled flight duty period will exceed the limits in Table B of this part." The introductory exception is part of the rule, and Table B holds the numbers: printed maxima for unaugmented operations run from 9 hours to 14 hours, varying by the scheduled start time of the duty period and the number of flight segments.

When a chain of this kind eats into that budget, eCFR, 14 CFR 117.19, Flight duty period extensions provides a limited release valve, not an open one. Paragraph (a) opens "For augmented and unaugmented operations, if unforeseen operational circumstances arise prior to takeoff:" and (a)(1) then says "The pilot in command and the certificate holder may extend the maximum flight duty period permitted in Tables B or C of this part up to 2 hours." Paragraph (a)(2) limits how often: "An extension in the flight duty period under paragraph (a)(1) of this section of more than 30 minutes may occur only once prior to receiving a rest period described in § 117.25(b)." Paragraph (a)(3) bars using the extension to exceed the cumulative limits in 117.23(c); (a)(4) requires the certificate holder to report to the Administrator within 10 days any duty period exceeding the maximum by more than 30 minutes; (a)(5) requires corrective action within 30 days.

The ceiling is finite and stepped. A 14-hour scheduled maximum extended by the 2 hours that 117.19(a)(1) allows reaches 16 hours, subject to the cumulative limits paragraph (a)(3) preserves. Past that, the answer is not a longer delay but no flight.

The crew clock: Table B maxima and the 2-hour extension in 117.19 Printed maxima in Table B to Part 117 for unaugmented operations run from 9 hours to 14 hours, varying by scheduled start time and number of flight segments. Section 117.19(a)(1) permits an extension of up to 2 hours, so a 14-hour maximum can reach 16 hours, subject to the cumulative limits preserved by paragraph (a)(3). An extension of more than 30 minutes may occur only once before a rest period, must be reported to the Administrator within 10 days, and any corrective action must be implemented within 30 days. A stepped ceiling, not an open one Unaugmented operations. Table B maxima vary by scheduled start time and number of flight segments. 9 hours up to 14 hours + 2 h lowest printed highest printed in Table B 117.19(a)(1) extension reaching 16 hours Conditions attached to the extension More than 30 minutes of extension may occur only once before the rest period in 117.25(b). The extension may not be used to exceed the cumulative limits in 117.23(c), per 117.19(a)(3). Extensions beyond the maximum by more than 30 minutes are reported to the Administrator within 10 days. Corrective action, where the circumstances were within the carrier's control, is implemented within 30 days. Source: 14 CFR 117.13, Table B to Part 117, and 14 CFR 117.19.

A Cancelled Flight Is Not a Late Flight

The last step changes which table the event lands in. Under 14 CFR 234.2, on-time performance is the percentage of scheduled operations of a specific flight that a carrier operates on time during a month. A cancelled flight is a scheduled operation the carrier did not operate on time. The delay that built up across the afternoon, having already shed its cause at the turn, is now recorded as a cancellation.

The cancellation is still reported, and Technical Directive No. 40 requires causal data for it. But cancellations and delays are counted in different places, so a reader who looks only at an on-time arrival percentage is reading a statistic computed over the flights that survived the chain.

What the Tarmac Clock Measures Instead

A fourth clock runs in parallel and measures something the delay fields do not. Part 259 defines a tarmac delay as "the period of time when an aircraft is on the ground with passengers and the passengers have no opportunity to deplane." eCFR, 14 CFR 259.4, Contingency Plan for Lengthy Tarmac Delays requires at paragraph (c)(1) that "For all domestic flights, each covered U.S. air carrier shall provide a passenger on a flight experiencing a tarmac delay at a U.S. airport the opportunity to deplane before the tarmac delay exceeds three hours in duration, subject to the exceptions in paragraph (c)(3)", with four hours as the limit for international flights under (c)(2). Paragraph (c)(3) lists three exceptions, including one in which "Air traffic control advises the pilot-in-command that returning to a suitable disembarkation point to deplane passengers would significantly disrupt airport operations".

Paragraph (c)(4) sets an earlier obligation: the carrier must "provide adequate food and potable water no later than two hours after the start of the tarmac delay, unless the pilot-in-command determines that safety or security considerations preclude such service". That clock starts at the beginning of the tarmac delay, not at the published departure time and not at the fifteen-minute mark that governs the delay fields. A flight can be inside the tarmac rule and outside the causal reporting thresholds at once.

Where This Doesn't Apply

The reporting rule has a narrow perimeter. Part 234 reaches only a reporting carrier: one certificated under 49 U.S.C. 41102 that accounted for at least 0.5 percent of domestic scheduled-passenger revenues in the most recently reported 12-month period. A reportable flight is "any domestic nonstop scheduled passenger flight, including a mechanically delayed flight, held out to the public under the reporting carrier's code, to or from any U.S. large, medium, small, or non-hub airport". Cargo operations, charters outside that definition, general aviation, and international segments are not counted.

The FAA counter has its own perimeter: OPSNET counts delays to IFR traffic caused by the ATC system detaining an aircraft. Time lost to a carrier gate hold, a maintenance check, or an airborne speed reduction short of the fifteen-minute mark falls outside it.

Part 117 is narrower than it looks. Section 117.1(a) states that the part "prescribes flight and duty limitations and rest requirements for all flightcrew members and certificate holders conducting passenger operations under part 121 of this chapter." Table B is not a universal limit on every commercial flight crew.

Part 259 applies to a covered carrier, defined as "a certificated carrier, a commuter carrier, or a foreign air carrier operating to, from or within the United States, conducting scheduled passenger service or public charter service with at least one aircraft having a designed seating capacity of 30 or more seats."

Finally, the chain above describes how records are kept, not how much delay propagates. Nothing in the regulatory text supports a claim about how often one step follows another.

Reading a Delay Table With the Chain in Mind

Three habits follow. First, when a table reports a delay cause, check which of the five fields in 234.4(a) it came from; item (21) reports a fact about a different flight. Second, when a share looks small, ask whether the 15-minute coding threshold in 234.4(j) kept the delay out of the causal fields altogether. Third, when an on-time percentage improves, check the cancellation count for the same period, because 234.2 measures on-time performance against scheduled operations.

None of these rules is hidden: the thresholds are in the regulation, the causal fields are numbered, the substitution exception is in the technical directive, and the duty limits sit in a table anyone can open. What they do not do is travel together. The FAA record knows the ground hold. The carrier filing knows the late arrival. The next flight's filing knows only that an aircraft was late. By the cancellation, the afternoon survives as separate entries in separate systems, each accurate about the question it was built to answer.

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