Corvane Air: Operations Case Study with Answer

An aircraft leaves late when the check takes longer than the 7-hour window. So I would first size the problem (how much of the on-time drop comes from late releases and what it costs), then break turnaround time into its steps and split them into hands-on work and waiting.

Then I would explain each slow step with its drivers on the demand side (how many checks, how much work per check) and the capacity side (mechanics, inspectors, bays, parts supply), and finally compare fixes on cost per delay avoided.

• Impact: delayed departures by cause, delays per late release, cost per delay, overtime cost.
• Demand: checks per night versus bays, work content per check (task cards), aircraft arriving late into the hangar.
• Process: turnaround by step, hands-on (inspection, repairs) versus waiting (parts, inspector sign-off, tooling, paperwork).
• Resources: mechanics, inspectors, parts availability and what changed in the 2025 cost program.
• Fixes: shorten the process, add capacity, or protect the schedule (spare aircraft), compared on cost and delays avoided.

What the interviewer is looking for

• Good: a process view of the check, not a generic cost tree.
• Strong: separates hands-on time from waiting time, which is how you test the COO's 'mechanics are slower' view against the head of maintenance's 'we are waiting' view.
• Excellent: flags the 2025 cost program as a likely cause because it touched exactly the support functions a night check depends on.

Push-back: The COO says the mechanics have simply gotten slower. What one number would settle that quickly?

Corvane flies about 9,000 departures a month (50 aircraft x 6 legs x 30 days). Delays rose from 1,170 (13%) to 1,350 (15%), an increase of 180 a month. Late releases from overnight checks went from 18 to 180 delayed flights, +162, which is 90% of the increase. Every other cause is roughly flat.

Late releases rose from 3 to 30 a month, and each one delays about 6 flights, the aircraft's full day. At $1,800 per delay, the extra 162 delays cost about $292,000 a month, or about $3.5 million a year.

What the interviewer is looking for

• Good: computes the 180-flight increase and sees that late releases drive it.
• Strong: states that 90% of the drop is the hangar and puts a yearly cost of about $3.5 million on it.
• Excellent: links 3 to 30 late releases to the 6-flight knock-on, so one late check costs about $10,800 in delays.

Push-back: A 2-point drop in on-time sounds small. Why should the COO care?

Paid hours per check rose from 64 ((4,500 + 300) / 75) to 72 ((4,500 + 900) / 75), up 12.5%, while the hands-on work stayed at 40 hours. The hands-on share of paid time fell from 62.5% to about 56%: each check now carries 32 hours of paid time that is not task-card work, up from 24.

Labor cost per check rose from $3,630 to $4,290, up about 18%, because every extra hour is overtime at $82.50. Across 75 checks a month that is about $49,500 a month, or $594,000 a year.

What the interviewer is looking for

• Good: gets 64 and 72 paid hours per check and the cost per check for both years.
• Strong: compares paid hours with the flat 40 hands-on hours and concludes the extra time is paid waiting, not slower work.
• Excellent: notes that the cost rise per check (18%) is bigger than the hours rise (12.5%) because every extra hour is paid at overtime rates.

Push-back: Overtime tripled. Doesn't that prove the hangar needs more mechanics?

Turnaround rose 0.9 hours, from 5.8 to 6.7. Every hands-on step is unchanged. Waiting for parts added 0.7 hours (78% of the increase) and waiting for inspector sign-off added 0.2 hours (22%). The mechanics are not slower; they are waiting.

Both waits trace to the 2025 cost program: closing the night parts counter and cutting one night inspector saved $300,000 a year. In return, the buffer inside the 7-hour window shrank from 1.2 hours to 0.3 hours, so any check with a long parts wait now runs past 5:30 a.m. The slower checks cost about $4.1 million a year ($3.5 million of delays plus $0.6 million of overtime), almost 14 times what the cuts saved.

What the interviewer is looking for

• Good: spots that the two waiting steps explain all of the 0.9-hour increase.
• Strong: ties the waits to the parts counter closure and the inspector cut, and uses the shrinking buffer to explain why late releases jumped tenfold on a modest average change.
• Excellent: weighs the $300,000 saving against the roughly $4.1 million it now costs, and says averages hide the tail: the late checks are the ones with long parts waits.

Push-back: The average check still fits inside the 7-hour window. How can 40% of checks be late?

Do options 1 and 2 together. They cut turnaround from 6.7 to 5.9 hours, under the 6.0-hour threshold, so late releases fall from 30 to about 4 a month (5% of 75). That avoids about 156 delayed flights a month, worth about $3.4 million a year, plus about $0.6 million of overtime. Against $320,000 a year in running cost, the net gain is about $3.6 million a year, and the $60,000 one-time cost pays back within days.

Option 3 (4 more mechanics, $396,000 a year) only saves 0.1 hours, leaving turnaround at 6.6, because more hands do not shorten a wait for parts or a signature. Option 4 (a spare aircraft) protects the schedule but does not shorten checks or cut overtime; even if it absorbed all 180 late-release delays it would be worth about $3.9 million, and it costs $2.4 million a year, 7.5 times options 1 and 2.

What the interviewer is looking for

• Good: picks options 1 and 2 because they target the two waits found in Exhibit C.
• Strong: shows the combined turnaround clears the 6.0-hour threshold and quantifies the net gain of about $3.6 million a year.
• Excellent: explains why hiring treats the wrong constraint and why the spare aircraft treats the symptom at 7.5 times the cost, and names the main risk of pre-kitting (forecasting the wrong parts).

Push-back: Pre-kitting depends on guessing which parts a check will need. What if the guess is wrong a third of the time?

Fix the waiting, not the workforce: reopen a night parts counter with pre-kitted parts and restore the third night inspector, for $320,000 a year plus $60,000 one-time. Checks slowed from 5.8 to 6.7 hours because of the 2025 cost cuts, late releases went from 3 to 30 a month, and they caused 90% of the on-time drop at a cost of about $3.5 million a year in delays plus $0.6 million in overtime.

The two moves bring checks back to about 5.9 hours and are worth a net $3.6 million a year. The main risk is pre-kitting the wrong parts, so we should pilot it on one bay for four weeks and track wait time by step every night before rolling it out.

What the interviewer is looking for

• Good: gives a clear recommendation and the root cause.
• Strong: quantifies the cause (0.9 hours, 3 to 30 late releases) and the value (about $3.6 million net a year).
• Excellent: rejects the hiring idea with a reason, proposes a pilot, and names what would change the recommendation.

Fix the waiting, not the workforce: reopen a night parts counter with pre-kitted parts and restore the third night inspector, for $320,000 a year plus $60,000 one-time.

Checks slowed from 5.8 to 6.7 hours because the 2025 cost cuts added 0.7 hours of parts waiting and 0.2 hours of sign-off waiting, while hands-on work stayed flat. Late releases rose from 3 to 30 a month and caused 90% of the on-time drop, costing about $3.5 million a year in delays and $0.6 million in overtime.

The two moves bring checks back to about 5.9 hours, avoid about 156 delayed flights a month and are worth a net $3.6 million a year. Hiring mechanics does not remove the waits, and a spare aircraft costs 7.5 times as much without shortening checks.

Next steps: pilot pre-kitting on one bay for four weeks, track wait time by step every night, and hold a 4:00 a.m. escalation call for any check at risk of missing 5:30 a.m.