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I was looking at flights from DEN -> MEM, and saw this extra-long route that FDX1311 took last night (9 Aug 2021) FDX1311 DEN-MEM 9 Aug 2021

Thinking they were probably just avoiding storms, I scrolled down and saw there were 3 other DEN-MEM flights under that flight number, all which also took the same extra-long route.

FDX1311 DEN-MEM 5 Aug 2021 FDX1311 DEN-MEM 29 Jul 2021 FDX1311 DEN-MEM 26 Jul 2021

What's the purpose of this extra long route? It's more than double the straight-line distance!

Ziwcam
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1 Answers1

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Purpose

FDX1311 is a daily scheduled flight, called a flying spare, or more colloquially a sweeper. It's a provision to remedy unplanned events which would otherwise prevent customers shipments to reach FedEx Memphis super-hub before dawn, and eventually to prevent shipments to be delivered in time.

Fedex sweep flight 1311

Fedex sweep flight 1311, Youtube

Route and reuse after landing

The flightpath is designed to allow the aircraft to be diverted to several airports in the US south area where FedEx has an important activity. When reaching Memphis airport, the aircraft becomes available for dispatching shipments from the hub.

Use cases

FDX1311 is part of FedEx contingency plan which, according to Fortune, comprises five aircraft to cover the whole US territory (to be compared to the 600+ aircraft fleet).

Diversion is triggered in quite different cases:

  • To fix unplanned maintenance. Aircraft availability and safety involves preventive maintenance and unavailability is well scheduled. But unplanned failures or damages still occur, some shipments can be left without a carrier. The spare aircraft will fix this problem.

  • To fix volume prediction errors. The number of containers can be predicted as soon as the shipments are collected, and aircraft can be dispatched accordingly for the next 24 hours. However there can be mistakes. Mistakes involving large volumes/weights cannot always be fixed with the planned aircraft. Containers in excess may be left at the warehouse. They will be collected by the spare flight.

  • To collect forgotten shipments. Errors may occur during containers preparation or loading into the holds, resulting in customers shipments forgotten or wrongly dispatched. The spare aircraft will get take them to Memphis in time.

Cost

According to FedEx each flight costs $30k. Most of the time it just flies this route empty or lightly loaded. Fuel consumption is about 30% higher than for the direct path.

Cost/benefit ratio

Individual customer shipments may experience delivery delays without large consequences, or without strong reaction. This is not the case for large customers for which contracts definitely include a delivery delay commitment, associated penalties and contract termination clauses for service failures.

I guess this $30k a day investment for this region is the quality assurance response to the evaluation of risks above, and those I'm not aware of. This is good for image, for competitiveness and for contracts renewal.

mins
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  • Excellent answer! In some ways similar in philosophy behind having air carriers provide a process for spare aircraft (even virtual spares as they are sometimes called) to accommodate out of service/ maintenance delays. Not the same of course, but designed from experience to manage customer expectations. Again, great answer. –  Aug 10 '21 at 19:47
  • That makes sense! Especially since FedEx will want all planes at Memphis in the middle of the night to sort and deliver. So if they need the plane in Memphis, which could easily be based on how many packages will be going to Denver that night, then sending it around, bringing it down somewhere along the way if necessary (e.g., DFW) can be easily worthwhile - a little extra fuel but more flexibility and the rest of the cost (crew, amortized cost of the plane) is the same. – manassehkatz-Moving 2 Codidact Aug 10 '21 at 23:21
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    @757toga I would guess the commercial implications are higher for freight carriers. If a few hundred units of self-loading cargo get delayed somewhere by a few hours, you pay the minimum legal compensation and that's the end of it. On the other hand, losing a long-term freight contract with a large company that is worth millions of dollars a year, because you screwed up too often, is a different scale of problem. – alephzero Aug 11 '21 at 00:20
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    @alephzero self-loading cargo - euphemism of the day. FedEx has the ultimate hub & spoke system, one which "self-loading cargo" wouldn't approve of. If FDX1311 takes a quick stop at DFW, yes it might be some high-value pharmaceuticals or electronics from big companies. It could also be a bunch of legal paperwork from small local law firms or last-minute gifts (think Mother's Day or Xmas, though those are seasonal, not every day). FedEx plans for these contingencies. The rest of the freight doesn't mind the extra 2 hours in the air, and a possible pit stop. Unlike "self-loading cargo." – manassehkatz-Moving 2 Codidact Aug 11 '21 at 01:08
  • @alephzero - reasonable point, but my comment was more directed on the techniques commercial operators use to address unexpected consequences affecting their customers' expectations (freight or passengers). Not certain I agree on your comparison metrics though. When a pax flight is canceled or significantly delayed the downstream consequences can be extremely impactful. The negative domino effect of a canceled/delayed pax flight can reach hundreds of people scheduled on that aircraft later in the day. But, I doubt there are data to compare the financial consequences of pax vs freight delays. –  Aug 11 '21 at 01:24
  • Could one say, with quite a bit of a stretch, that this is a sort of "Operation Chrome Dome" for air cargo? Always having some ready-units in the air, in case they are needed. – Dohn Joe Aug 11 '21 at 07:39
  • @DohnJoe: Chrome dome aircraft where flying in closed patterns for long hours. Remote equivalent today would be air refueling tankers and airborne radars. Sweepers instead have a programmed route with a landing destination. – mins Aug 11 '21 at 10:32
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    @mins So more a cargo air patrol (CAP) :-) – Dohn Joe Aug 11 '21 at 10:54
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    Thanks for the amazingly detailed answer! I'll admit being a bit ashamed that it seems simply googling the flight number would have led me to an answer, but you consolidated in your answer a fair amount of pieces of information from various sites. Thank you! – Ziwcam Aug 11 '21 at 17:48
  • Is it possible to explain this "sweep flight" thing a bit more or with a example for novice people like me? This is a interesting answer and so I thought that it Will be more easy if it's explained a bit more and there is no wikipedia article or much info. about sweep flight in Google. Thanks. – SwiftPushkar Aug 12 '21 at 06:27
  • @SwiftPushkar: I'll be happy to make the answer easier to understand, but I'm not sure what kind of details will help. Can you tell me what is difficult to get or appears strange for a person not familiar with aviation? – mins Aug 12 '21 at 06:32
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    @mins - Yes , aircraft unplanned maintenance and parcels left behind by the regular aircraft" part pls. – SwiftPushkar Aug 12 '21 at 06:39
  • "This is not the case for large customers for which contracts definitely include a delivery delay commitment, associated penalties and contract termination clauses for service failures" - Why are those large customers so sensitive to things arriving a day late? I can't think of anything you would ship as bulk air freight that would be ruined if it had to wait an extra day to arrive - stuff like industrial chemicals would be shipped by train or tanker truck rather than cargo aircraft, and high-value perishables like human organs would be hand-carried by fast charter jet. – Vikki Sep 05 '21 at 17:19
  • @Vikki: "Why are those large customers so sensitive to things arriving a day late?" They are conducting a business or a public service, they have their own commitments, and are looking for overall fulfillment of service level agreements from their subcontractors. E.g. for the US postal service subcontracted to Fedex, penalties might be triggered when there is more than 5% of their monthly shipments late by more than 12 hours, and the contract terminated if this occurs more than 3 times in the year. This is to illustrate. – mins Sep 05 '21 at 17:35
  • @mins: That's pretty hypocritical of the USPS to penalise FedEx harshly for delivering things late by less than a day when they themselves routinely deliver things days to weeks late. – Vikki Sep 05 '21 at 17:42
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    @Vikki. That an example, I know nothing about the contract with USPS. Individuals receiving their shipments late without compensation doesn't mean USPS large customers are not receiving damages. I know no large B2B contract without SLAs and penalties. – mins Sep 05 '21 at 18:18