Wet-lease crew duty and MEL across three States
A charter operator holding an AOC in State A has wet-leased a twin-jet registered in State B for a four-sector night cargo rotation beginning and ending in State C. One thrust reverser is deferred under the State B MEL (Category C, 10 days); the MEL permits dispatch provided landing performance is assessed without reverse thrust. The operator's OM-B limits flight duty to 12 h 30 min for a two-pilot crew, while State A's published rule allows 13 h. The first two sectors total 7 h 10 min, but a 70-minute ground stop is expected at State C because of a runway inspection. The commander calculates the first-day FDP will be 13 h 10 min and proposes to use the State A limit. Destination D's runway is 1,800 m, contaminated with wet snow, braking action medium, and its AIP states that reverse thrust may not be used to reduce the landing distance required. The crew has already been on duty 9 h, including a 2 h standby that the company does not count as duty.
1. Which flight duty limit governs the first day, and how should the 2-hour standby be treated?
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The binding limit is the one in the operator's approved OM-B: 12 h 30 min. State A's 13-hour rule is a maximum permitted by the State, not an entitlement that overrides a more restrictive company limitation. The commander cannot simply choose the State figure because it is more convenient.
The standby must be resolved against the OM definition. If the crew was at the airport, contactable and unable to use the time freely, it is normally duty and must be counted. If it was at a hotel with free time and a defined call-out, it may be rest, but that must be documented in the OM. On the facts given, the company's exclusion looks doubtful. Counting it would make the FDP at least 15 h 10 min, far beyond 12 h 30 min.
The practical conclusion is that the rotation cannot be flown as planned. Options are a delayed departure with a shortened duty, an additional crew, or splitting the rotation. The decision should be recorded and communicated to operations before the crew reports, not negotiated at the aircraft.
2. May the aircraft dispatch with the deferred reverser to destination D? What performance and regulatory checks apply?
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The MEL is a continuing-airworthiness document. It allows dispatch with the item inoperative subject to its conditions; it does not certify that the aircraft can land at a particular runway. Here the MEL condition itself requires landing performance to be assessed without reverse thrust, and D's AIP independently prohibits reverse credit on contaminated runways.
The crew therefore needs the AFM contaminated-runway landing data for wet snow and medium braking, with no reverse-thrust credit, plus the required safety margin. If that landing distance exceeds the 1,800 m LDA, D is not usable. The State B MEL approval does not override the aerodrome operating rule; the operator must also check whether State C requires notification or acceptance of the deferral.
If the data are marginal, the answer is not to 'use a bit of reverse anyway'. Change destination to a runway with adequate LDA, reduce landing weight, or repair the reverser. The MEL is not a performance waiver.
3. What is your decision and what should be recorded and communicated?
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Do not dispatch as planned. The duty limit is already at risk and the destination landing performance is not assured. The commander should tell the operator that the flight cannot proceed until either a compliant crew is available or the aircraft/destination is changed.
Record the standby treatment, the calculated FDP, the landing-distance calculation without reverse, the AIP reference and the MEL reference in the flight folio or tech log. Notify the charterer and operations control so that the commercial pressure is visible and not left to the crew. If the aircraft is already airborne, make the diversion decision early rather than arriving at D with insufficient landing margin.
Human factors matter here: a commander who has just come off standby and is facing a night rotation is susceptible to 'get-there' pressure. A written decision with reasons protects the crew and gives the operator a clear basis for a replacement plan.