Two Bays, Three Aircraft, One Deadline
You are the cadet duty scheduler for a training wing with two maintenance bays. Aircraft A needs a 3-hour inspection and must be ready for a 09:00 sortie. Aircraft B is the standby aircraft for a search-and-rescue tasking at 13:00; it needs a 3-hour repair, but the spare part is due at 07:30, plus a 1-hour test flight. The only test pilot is available 08:00–10:00 and 12:00–13:00. Aircraft C needs a 3-hour inspection followed by a mandatory 2-hour cooling period before release, and is needed at 14:00. Bay 1 is free from 06:00. Bay 2 is free from 06:00 but blocked 08:00–09:30 for calibration. Crews work 06:00–14:00; cooling does not need a crew. No aircraft can be moved to another base. At 06:00 the part is confirmed for 07:30; at 07:10 it is reported delayed to 09:00. You must re-plan.
1. Build a feasible schedule before the delay. Justify the order.
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Feasible schedule with the part at 07:30:
- Bay 1: A 06:00–09:00 (ready 09:00). Then C 09:00–12:00; cooling 12:00–14:00 (ready 14:00).
- Bay 2: B repair 07:30–08:00 (0.5 h), calibration block 08:00–09:30, B repair 09:30–12:00 (2.5 h) = 3 h total. Test flight 12:00–13:00 with the pilot. B ready 13:00. This meets all three deadlines. The key reasoning is that B's repair can be split around the calibration block, and the test flight must use the 12:00–13:00 pilot window. C's cooling needs no crew, so it can run to 14:00 while crews finish other work. A must not be moved because its 09:00 sortie is the hardest deadline.
2. At 07:10 the part is delayed to 09:00. What do you protect and what do you sacrifice?
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At 07:10 the part is delayed to 09:00, so B cannot start its repair at 07:30. Two options: Option 1: keep C in Bay 1 09:00–12:00 with cooling to 14:00; put B in Bay 2 09:30–12:30. B's repair now finishes after the 12:00–13:00 test window, so B is not ready at 13:00. Option 2: put B in Bay 1 09:00–12:00 and test 12:00–13:00, making B ready on time; put C in Bay 2 09:30–12:30, cooling 12:30–14:30, so C slips 30 minutes. I would choose Option 2 if the search-and-rescue standby is the higher operational priority. B is the aircraft that may be launched for a life-critical task; C's 14:00 need can be met with a 30-minute extension or a substitute. I would notify operations immediately, ask for the extension, and record the trade-off. If C's tasking were immovable and B could be covered by another station, the decision would reverse.
3. State your assumptions and the communication actions that make the plan work.
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Assumptions to state: the part arrives at 09:00 and is serviceable; the calibration block does not overrun; the test pilot is on time; the test flight finds no defect; cooling can be monitored without a crew; and no aircraft needs a bay for a higher-priority defect. Communication: tell maintenance control, operations, the test pilot, and the C crew. Publish a revised board with times and owners. Set a trigger: if the part slips past 09:30, B will not make 13:00; operations must then choose between B and C rather than let both slip. Record the decision and the reason. The reasoning is that a scheduler's job is not to produce a pretty plan but to make the trade-off visible before it becomes a surprise.