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Orlaam

Return versus Diversion

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How often do flights simply return to the DEP airport when unable to land?  What is the criteria?  I see more domestic short flights simply returning, as opposed to diverting to an alternate.  I watched a Horizon Dash-8 fly from SEA to RDM, then hold for like 30 minutes and return to SEA.  RDM was BCAT1.  Do they simply plan on a return if the fuel will allow before departure?

 

In other words, a short to medium haul with planned fuel (+cont, FAS reserves, extra, ect..) only plans a shorter distance diversion, then obviously the plane couldn't go back.  I understand for long hauls, but for shorter distances, do they typically just plan for a return as an alternate?

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How often do flights simply return to the DEP airport when unable to land?  What is the criteria?  I see more domestic short flights simply returning, as opposed to diverting to an alternate.  I watched a Horizon Dash-8 fly from SEA to RDM, then hold for like 30 minutes and return to SEA.  RDM was BCAT1.  Do they simply plan on a return if the fuel will allow before departure?

 

In other words, a short to medium haul with planned fuel (+cont, FAS reserves, extra, ect..) only plans a shorter distance diversion, then obviously the plane couldn't go back.  I understand for long hauls, but for shorter distances, do they typically just plan for a return as an alternate?

 

Depends on the issue. If it's a medical, then you want to be on the ground 5 minutes ago, so unless you're closer to home, you're going to an alternate. If it's some other time-sensitive thing, then you're probably going to an alternate. If it's something maintenance related that isn't hugely time sensitive, then you may return to the origin simply because landing at the suitable alternate won't do you much good. "I need to get the plane fixed / looked at...Greenland sounds like a great choice, right??? Tons of maintenance facilities there..." Nope.

 

You generally talk to ops as well to determine their thoughts.

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As Kyle says, there are both operational and commercial considerations. If you dump your pax in the middle of nowhere with no hotac and no connections, they're going to be upset. They may be better off at main base where there are plenty of your own airline staff on hand and other flights to rebook them on to.

 

Likewise, spare parts and maintenance facilities are not available in every airport you might divert in to across the world either, so if it is safe to do so then it is generally better to go somewhere that the airline can easily get the spares and/or has engineers or an engineering contract (ie an airport served by the airline already or home base).

 

They may not have planned a return as the alternate as such, but given the weather they will likely have loaded plenty of extra fuel, plus fuel for the planned divert. It may well have been that they looked at the situation, did the sums and decided (likely with the input of the company, as Kyle says) that a return to Seattle was both feasible and the most commercially sensible option.

 

It's not just short-haul flights -- I've seen a 747s bound for CPT turn back to London whilst over north Africa. 10hrs in the air just to end up back where you started!

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From a short haul ops persepctive, if I have an airframe doing 8- 12 sectors a day, I have a bigger picture to consider,  We never want to upset the pax, but if we have another 6 sectors to cover, and this is the crews last landing of the day, do we spend 2 hours holding waiting for weather that may never clear, or do wo cut our losses with the 50+ pax on the flight alredy and try and recover the program to keep disruption to a minimum for the 250 odd still waiting to fly that day.

​The more landings a crew does, under JAR, the less time the can operate, so you have to factor that in to the plan as well, getting the airframe back to base means not only do you get to go again, rebook and stuff, but you get a fresh new crew (that's if it's schedualed to happen) as mentioned above

Sometimes airline ops is a head mush, you can go days sitting around waiting for something to happen, and then BAM, 5 go tech (including the standby plane because some donkey left the batteries on), the weather closes in and then all hell breaks loose, (and that was with a 78 aircraft European operator back in the 2000's)

​Its when the first flight of the day goes up the creek, trying to recover that can be a real pain in the cheeks.

​As my closing thought, there are generally three things an ops guy/gal NEVER wants to hear... "It needs an engine change", "It's Snowing" and "are you having a quiet day"

​Liam Reynolds
 

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It's not just short-haul flights -- I've seen a 747s bound for CPT turn back to London whilst over north Africa. 10hrs in the air just to end up back where you started!

 

I have seen LYs 744 bound for the JFK/EWR(not sure) turn around just 1H(around 5-6H from takeoff) into the atlantic and fly back to TLV(10-11 Hours of a tour over Europe) due engine failure.

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So this begs the question though, how much extra fuel are we carrying here?  You want the plane to be light on fuel, however, figuring in minimums and other factors, how often do those numbers allow a return?  I mean I took a relatively short flight, for me, from BUR to PDX last night with extra total coming to 11,000 lbs.  It wouldn't allow me based on payload to even derate that much without landing calculating above MLW.  Now I could return on that flight since the total flight burn was low enough, but if the flight had been more like 5 hours?  No way. 

 

How much should I be figuring in for holds and contingency?  I realize these numbers are far from static, but an average 737 flight would call for what?  I've been planning for 30 minute holds and 20 to 30 minutes contingency.  With reserves and diversion, it hasn't left me with much.  Anymore often prevent much derate and tells me the MTOW is too high.  Again, I usually land with 10-11 thousand pounds without G/As or other unforeseen factors.  I'm using PFPX and all my numbers are matched.

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How you plan this all out depends on the regs. We could write pages about the idiosyncrasies but if you want a decent baseline to shoot for try this. Pick the airport you want as your alternate, then put on enough fuel to fly to the destination, then to the alternate and then for another 45 mins on top of that.

 

What airport was your alternate for your PDX flight?

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How you plan this all out depends on the regs. We could write pages about the idiosyncrasies but if you want a decent baseline to shoot for try this. Pick the airport you want as your alternate, then put on enough fuel to fly to the destination, then to the alternate and then for another 45 mins on top of that.

 

What airport was your alternate for your PDX flight?

 

I picked KSEA.  Seemed like the best choice for the area.  Usually in places like SoCal, I choose a closer one but look at weather predictions too.  So for BUR I chose LAX as my alternate on that leg.

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Only take what you need. We used to be even able to use the adacent runway as the alternate,(not sure if that's allowed these days???  (I think it needs to be a cavok day, and a few other things to be followed, it's not standard practice - I'm talking back in 2000-2004 ish)

​There are many ways to eat a cow, and ultimately its the captains discression. the FAA/JAR will dictate a MINIMUM of what you should be carrying in terms of fuel, but if you as a captain, can see that they will issues down route, yet there be a strong chance of getting in even tho the weather/traffic is naff, and if you have underload to play with, then yeah go for it, uplift your planned fuel + whatever you can get away with without going over MTOW/MLDW, any fuel you don't use gets used on the next flight anyway besides, fuel might be cheaper at your airport of origin 

​From an ops point of view, i'd rather you have more fuel than you need, then you call me up on the radio telling me your diverting, all because you decided not to take enough fuel for a problem we could all see happening. - sometimes, you cant take more, that's just the way it is,  

​Iv had captains ask me if they can just fill the tanks, and depending on where they are, and how much we fly into an airport, and how much it costs for fuel at the destination then we will plan for them to tank the fuel, i'v shipped an A321 with 21T of fuel for a 4 hour flight before, because there was no fuel available at the destination, it was pretty much at Max Ramp weight when it pushed. 

​With my own simming I quite often take more than I need just to play around with the weights, in fact a recent 777 flight, I did OERK-KJFK went with 145T of fuel when it needed 120T,  why? I just wanted to see how the plane flew when it was as full as it was, I had an available under load of 3000kgs, and we landed about 3.5 under the MLDW

When I fly the 737 on short hops ill plan my flights backwards, always landing with the fuel that I need for the next sector.
​~
Liam Reynolds.

 

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Liam of course brings up some great points. And just so you know Orlaam, I gave you the basic FAR Part 91 fuel requirements which you can look up if you wish.

 

One interesting thing, and I believe Liam is eluding to things like this, is that even though your flt planning software tells you that it'll take say... 2000lbs of fuel to fly to your alternate, it probably will be more than that. Possibly a lot more. The controllers aren't gonna send you direct to JFK and make you number 1 for landing after you go miss at White Plains. In other words, what's legal isn't always safe.

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:) Thanks Joe.

If the flight plan says 2254lbs im taking 2500lbs, Round it up every time.

​Liam

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in the old time of classic and beginning of -400s while dispatching we had a little manual with acceptable airports for diversion (called preference ones) and the one listed for emergency only as the maintenance will be hard to get or even getting pax attention. i assume and think that some 747 operators are still doing it ... do not forget too that politics made some diversion airports not available depending of your operations and your country diplomatic ....or not. 

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As many people have said, it depends on quite a lot of things: favourable winds, predicted weather at the choice you favour, facilities for repair, medical facilities, replacement aircraft availability, passenger facilities, how suitable the runway is if a fault will affect landing speed or braking, airport emergency facilities, available nav aids, surrounding terrain, crew qualifications for certain types of approaches, etc, etc.

 

On occasion the wrong choice has proved fatal, famously in relatively recent times at Kegworth in the UK, when British Midland Flight 92, flying from Heathrow to Belfast diverted to East Midlands (EGNX) but crashed on the M1 about 900 yards short of the runway threshold. Depending on whose side you take, blame for the crash usually either gets attributed to poor type conversion training (i.e. the crew only had a one day course on converting from the 737-200 to the then-new 737-400 and made an incorrect assumption based on their greater knowledge of the earlier model's characteristics, which led them to shut down their one good engine and then overstrain the one which actually had a fault), or, if you side with the crew, poor engine instument layout design on the part of Boeing. Or possibly both.

 

But what rarely ever gets mentioned in relation to that accident, is when the problem was initially detected, the aircraft could have easily made Manchester or Liverpool, in fact if I recall correctly, it was within about 25 miles of them both when the problem occurred, and thus could even have glided all the way in to either of them given that most airliners commence their let down from about 50 miles out, but the ground maintenance personnel which the crew contacted when the problem arose, although leaving it to their discretion, apparently chivvied them into stretching their luck on one engine to instead go all the way to East Midlands because that was easier from a maintenance point of view, since British Midland had a facility there; an occurence which, in my opinion at least, should have garnered far more criticism. One suspects if they were actually sat there on board looking at flames shooting out of an engine, they'd not have been advocating staying up there any longer than necessary.

 

Of course the Captain should have told them to stick it and gone to somewhere nearer, but at the time he was somewhat trusting of the notion that a twin engine failure is under normal circumstances a really rare occurrence.

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I have seen LYs 744 bound for the JFK/EWR(not sure) turn around just 1H(around 5-6H from takeoff) into the atlantic and fly back to TLV(10-11 Hours of a tour over Europe) due engine failure.

 

To generalize there are failures (and other non normal conditions) that require to "land at nearest suitable" by most operators' policy.

While an engine failure on a twin is definitely a "land at nearest suitable" scenario, on a quad is really a matter of performance (altitude penalty), fuel endurance, weight (overweight landing), landing distance required and of course company requirement (mainly commercial & maintenance related).

In all the cases that do not fall into "land at nearest suitable", as captains we would be more prone to listen to company suggestion/requirements when taking a decision, while we might completely disregard their wish in a "land at nearest suitable" scenario, where all considerations are with regards to safety.

 

Mike

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